2008 p0340

2008 Aveo, 50K on the car, 1.6L engine, 5 speed transmission, NO A/C
I replaced the timing belt, spark plugs, and valve cover gasket (oil in the spark plug wells) just before 50K. I have a 2009 Aveo with the same engine-transmission combination, so I let the 2008 sit for a year but ran the engine several times over that year, and connected a battery maintainer on the 2008.

In Jan 2018 I started driving the 2008 Aveo and noticed the fuel mileage dropped from 36 MPG in the summer time to around 28 MPG in January. This is normal because the cold weather calls for a richer air/fuel mixture, the cold thickens the oil and greases plus the refinery’s increase the amount of Heptanes (vaporizes faster than summer blend gasoline) and heptanes leads to lower MPG. Anyway the Heptane information was from a friend that works at an oil refinery. I know in past years when it was minus 15f the fuel mileage went down to 28MPG so I didn’t think it was abnormal because January was a bone chiller this year with lots of -0F days

I have been driving the 2008 Aveo for 2 months when the check engine light (CEL) came on and the car started bucking when lightly accelerating. I got a P0340 code (camshaft position problem) on my Innova OBD-2 code reader. I replaced the camshaft sprocket position sensor, checked all 3 timing marks to make sure I installed the timing belt kit correctly and drove the car for a couple of days and the code came back. I drove the 2008 Aveo some more and the CEL went off for about day. The CEL came back on a day later, then went off for an hour, then came back on.
If I let off of the throttle when coming up to a traffic light or behind a slower moving car and then accelerate a little, the engine bucks a time or two and then runs OK.

I bought a second new cam sprocket position sensor and another new timing belt but I haven’t installed it yet. Today I removed the top timing belt cover again and all of the timing marks seem to be where they are supposed to be. I bought a camshaft sprocket tool that goes between the cam sprockets for a 1.6L Chevrolet but the metal cam sprocket holding tool halves do not fit between the sprockets so the tool must be for a different 1.6L Chevy engine. When I changed the original belt, the sprockets moved a little and if this tool I bought would have worked and fit, the cam sprockets can’t move while installing the belt. I borrowed a universal cam sprocket holding tool from O’reiily Auto Parts when I replaced the timing belt but it allowed the sprockets to move a little.

The engine seems to have all of the normal power, but bucks when accelerating just a little. It might crank a little longer when starting but I haven’t noticed anything else that is different. I have not done a compression test. I have read the compression should be around 200PSI.

I do have one concern about the timing marks. When I align the cam sprocket timing marks, the crankshaft mark is a little less than 1/16” from being exactly on the timing marks on the crankshaft and the notch at the front of the engine. I was wondering if anyone got a slightly short belt or the idler pulley might have been a fraction of an inch bigger. My thinking is if the belt was just a fraction shorter or the idler pulley was a little bigger, the crankshaft mark would be shy of where they were supposed to be. My first replacement timing belt kit and water pump was Korean. The timing belt I just bought was made by GoodYear. I haven’t installed the second replacement Goodyear belt or the 3^rd cam position sensor yet but will be doing that tomorrow or in a few days.

I read a couple of repair blogs where a crankshaft sensor replacement where you had to do a “re-learn” process but I haven’t read that changing the cam sprocket position sensor needed to have a re-learn carried out.

The cam sprocket sensor has a 12V supply wire, a ground wire, and a signal wire. I haven’t measured the 12 volt or ground connections. I understand the signal wire value needs a scope to read the value. I also have not checked the Cam position wires for continuity from the sensor back to the ECM. I found some web pages for a 2011 European Aveo with a 1.2 and a 1.4 engine that have electrical schematic but not for a 2008 Aveo

Anyone have a similar situation and managed to fix it?
Would connecting a scope tell me if the position signal is out of time? I had a Marquett scope when I worked for an auto dealership back in 1985 but things have changed since then.
I was looking at a dongle and an OBD-2 Android app for under $100 but I don’t think it would tell me much more than what my Innove OBD-2 reader would tell me. I am hesitant to spend the $500 to $2,000 for some of the scopes I saw Youtube videos of. The “BlueDriver” OBD-2 has several good write ups but I think it might not tell me that much more than the Innova unit I have.


Summary
2008 Aveo bought new, 50K miles, P0340 codes, bucks when lightly accelerating, 1 new cam position sensor, 1 new belt, checked the timing marks two times-off by 1/16” at the crankshaft when the cam sprockets are perfectly aligned, cam sensor wires visually check OK but no other tests. The car sat for 1 year, the engine was run several times, and drove Ok at first, then the CEL came on.

9/Sept/2018
I took the valve cover off and used a bicycle spoke on the top head surface to see where the cam sprocket timing marks were. Both cam sprocket marks align with the top of the head. This is a way to verify the marks. Honda uses this method and it works on 2008 and older Aveos.

I moved the exhaust cam sensor a little towards the front of the car or closer to the center of the exhaust camshaft and now 95% of the bucking is gone. I still get a cam/crankshaft correlation error so I am suspecting there is some correlation relearn procedure needs to be done. No camshaft relearn is talked about in repair manuals but a crankshaft relearn is.

Problem solved, the leaking oil from the valve cover got down into the spark plug wells and made carbon tracks inside the spark plug wire boots so the electricity that makes the spark was going to ground from the carbon track inside the boot, when the engine was under load or accelerating. One spark plug had a carbon track from the top of the plug where the plug wire slips over the spark plug all of the way to the base of the spark plug.

New sprk plug wires and 2 new spark plugs fixed the problem.

Any chance the cam sensor wiring harness was damaged when you did the timing belt job? In any case, I suggest first doing a continuity test of those wires, from the cam sensor connector to the ECM connector. If the continuity is good, then check for ground and reference at the connector, and back probe (or use a wire-piercing adapter) on the signal wire. (all you'll get from that is a fairly steady voltage or frequency). If all of that tests ok, then you could do a complete test of the signal by taking it to a shop having a scope, instead of buying one.

EDIT: After posting, I realized that I was thinking of the crank sensor, and that the cam sensor is different. So, all you need to do is test the pink wire at #1 for power, the black wire at #2 for ground, and then the remainder of what I wrote above applies to the signal wire at #3.

I rechecked the camshaft timing marks ans they were on target.

Next I measured the voltage at the cam position sensor pinkish-reddish wire and got battery voltage. The ground terminal had almost zero ohms resistance. I started the engine and got around 2.5V from the signal wire. I removed the battery and disconnected and reconnected the wiring harness gang connectors from the ECM. I loosened the body and engine grounding wires and re-tightened them. I had a 3rd cam position sensor so i installed it.

When I changed my timing belt a year ago there was oil in the spark plug wells so I installed new platinum spark plugs. Last week I used an ohm meter on the spark plug wired and the resistance was in line with specifications. This time there was NO oil in the spark plug wells.

Before the car sat for a year and after the new timing belt kit my fuel mileage was around 36 MPG. After a year it dropped to 30 MOG, then 24 MPG when the temperature was -15f. When the weather warmed up to 60F, my fuel mileage was still below 30 MPG for several weeks but I only drive a couple hundred miles in a month. My last fill-up had me at 42MPG. Crazy because my best fuel mileage was 39.5 MPG going 65 MPH on the interstate.

My latest symptoms are:
NO cam position CEL light where before it would come on and then go off several times.
The engine still bucks 2 times if the RPMs are low and I accelerate lightly.
It seems like the more I drive the car in days, the less it bucks.

I have a friend that inherited his dad's 2009 Aveo that sat for 3 years. I told him to drain the gasoline but he refused. He had several codes and the engine would not go much past idle sometimes and would even stall. He drove the car and used 3 tanks of gasoline and now the engine runs OK. He never did any repairs or parts swaps. My idea is these Aveos do not do well sitting. Has anyone else experienced some poor engine performances after the car sat for a long time.

Engine on TDC, cam marks lined up
Attachment 11518
Attachment 11522

Battery voltage at cam position sensor feed
Attachment 11519

Ground resistance at can position sensor wire
Attachment 11520

Spark Plug wire test 2K to 5K per foot
Attachment 11521

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Originally Posted by OG-Lou

.... When I changed my timing belt a year ago there was oil in the spark plug wells so I installed new platinum spark plugs. ....

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There have been multiple reports from Aveo owners who had performance problems after installing platinum plugs, and which were resolved when they switched back to copper. I've never used them on our Aveos, so I can't confirm this myself, one way or the other. I also don't understand why platinum plugs would cause problems, but the reports were from reliable people, so I don't doubt what they said. Given that it's fairly inexpensive, you might want to try copper plugs to see if makes any difference on your vehicle.

I've had my Aveo sitting for more than 2 weeks at times, and it never had any performance problems as a result of doing that. I'll also mention that my Aveo's MPG has been remarkably consistent over 13 years - around 30 in the Winter, and 32 in the warmer seasons, always using 10% ethanol 87 octane gas.

I re-gaped the old spark plugs that came with the car (when the engine was running perfectly) and still have the bucking (2 bucks) when I apply light to medium throttle pressure. If I only apply very light throttle pressure, the engine doesn't buck. (decelerating to slight acceleration engine speed under 1,500 RPM. At higher RPM it bucks less)

I have two choices now regarding spark plugs, try different gaps and try new spark plugs. I say try different spark plug gaps because my old plugs had a gap of .046 so I set it to the minimum .040 I found a range of 040 - .044 on one site (Rock Auto) that sold Aveo spark plugs.

Back in 1964 I worked in an auto repair shop and we had a spark plug tester where we could change some of the test inputs. The higher the air pressure we applied, the more the spark plugs failed. I don't remember if we could adjust the spark voltage or not. We also did some night time tests to see if there was any glow around the porcelain to steel shell base, which was how well the gas seal was between the ceramic and steel.

What I found was most spark plugs failed the tests if the gap was correct (.035 then) and center electrode was rounded off. Square off the center electrode and remove a little ground electrode metal by filing it a little and it passed the test with flying/winning colors.

More spark plugs failed as the air pressure was increased. Back then the debate was which brand of spark plug worked the best. Most popular brands were the same. I did find some no-name brand spark plugs had a glow between the steel and porcelain at night. Several engines at that time were completely visible so the glow test was easy to do. I will say the test device was fairly low tech.

A couple years later the shop bought one of those big fancy automotive oscilloscopes. It was magic at first, then I learned a scope measures time and voltage. I transferred some of the knowledge I gained using the scope to hand held tools that measures voltage and resistance. The most applicable meter for spark plug wire test was how much resistance a plug wire had was the ohm meter. I marvel at how simple it is to test spark plug wires when I read how many people replace spark plug wires but never test them.

Of course ohm meters do not replace digital scopes in some situations but with spark lug wires and wiggling the wire as several places,an ohm meter is a low cost way determine good from bad spark plug wires. A few times when I found a bad wire, I cut off an inch and re-attached a connector. It worked until I could buy new wires. In one shop we made wire sets from individual parts and a roll of spark plug cable that worked as well as an OE part. A special crimping tool was the key to making up a wire/cable that lasted.


I read there was a recall on 2009 Aveos because the spark plug boots were defective but nothing on 2008 Aveos. My Aveo was built in 2007 around Sept.

I bought a can of Mass air flow sensor cleaner but I haven't used it yet. I will look again for any air leaks.

I have a reference to an independent repair shop with some sort of digital scope but have not contacted him.

An OBD realtime data stream reader might be a big help in diagnosing that bucking. It would enable you to see if the fuel trims are changing at the point the bucking takes place, and (if they are) if the trims are showing rich or lean. And you would also be able to find out if any misfires are being counted by the ECM. The Torque app for Android is a popular and less expensive choice, or there are readers available off the shelf as well.

Also just an FYI that in 2009 the second gen Aveo began using COPs, and that's what that recall is for. So your 2008 could not be included in that particular recall.

COP=Coil on plug

I found my book for my Innova 3120 and have been reading it. It does some freeze frame data. I still have to learn how to use the 3120. After I understand what I am looking at on the scanner and what I should be measuring, I will connect the 3120 and do a road test.

I watched several Youtube videos about WiFi Android dongles that plug into the data port(DLC). Several people like the ELM327 ~$14.00, the BAFX 34t5 ~$25, the OBDLink MX ~$90, and most of all the "BlueDriver for ~$100.

Does anyone have a favorite scanner under $200? I am leaning towards the "BlueDriver."

I did re-gap the spark plugs to .044 and it didn't change anything. I ordered 4 new spark plugs, the same as came with the car.

I connected my Innova 3120 code reader and found a new code but no CEL/MIL P0113 AIT=air intake temperature circuit 1, high input. The FF freeze frame data indicated the air intake temp to be -40f. The outside air temp was around 68f so i know the reading was off. I borrowed a Bosch code reader and it said the intake air temperature was 128f.

So now I have to update my Innova 3120 or determine if it even works on streaming data for my 2008 Aveo. I bought the scanner used so maybe it was not working correctly (seems to read codes well) but the streaming data readings are way off. The RPM stays at 1,400 no matter and the road speed and the speedometer always reads 0 MPH.

I tested the 5V (actually 4.8/9V) signal wire voltage and found 4.9V. The ground wire measured .1 ohm whis what my meter registers when I connect the 2 leads together. I put my meter on 2K ohms and the AIT sensor measured 16.4K ohms at driveway temp of around 78f. I removed the AIT sensor and used a hair dryer to heat the thermister. The ohms vary from 1540 room temp to 760 ohms when the ATI sensor is sort of too hot to hold in the hair dryer air stream/ That is about how it is supposed to work but i don't have the exact specifications.

I watched several Youtube videos about how an AIT sensor works and how to bench test the sensor so in general my AIT sensor moves in the correct directions.

On youtube "Scanner-Danner" "Schrodingers Box" and a few other guys really get down to testing circuits with mostly basic test instruments and explain the how and why things work. The both claim too many parts are thrown at a problem/s that really do not fix the issues a car is having. The videos are not quick fixes and require time and an understanding of the problem and how things work.

I bought new spark plugs (50K on the old spark plugs) on eBay and they arrived today so I gaped them, applied a little anti-seize and installed the new spark plugs. The old #1 and #4 spark plug were a light tan but #3 & #4 where bone white.

I had a lot of yard work to do so I haven't done a road test. I am also waiting on a cable to connect my Innova 3120 to my computer. It came with a 25 pin serial cable but all I have computer wise is USB and maybe an old 9 pin serial port. Yes the Innove 3120 is getting old and maybe it was never up-dated or it could be toast. Fingers crossed that an update works for my 2008 Aveo. If not that "BlueDriver" dongle looks like it will be my next purchase, UNLESS I find a Snap-on MODIS 4 channel $500 + leads. Snap-On sold today for $700. Another option is an older Pico Scope for $250.

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Originally Posted by OG-Lou

... So now I have to update my Innova 3120 or determine if it even works on streaming data for my 2008 Aveo. ...

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I believe that your scanner is ok about that freeze frame data, given that the OBD code and the IAT sensor reading were consistent with each other. Keep in mind that freeze frame is single point-in-time data, and can't be validated or invalidated by subsequent testing. Try clearing the code and see if it comes back.

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... The old #1 and #4 spark plug were a light tan but #3 & #4 where bone white. ....

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To me that's a bit of a red flag. You made a typo, but it's clear that 2 plugs were substantially different from the other 2. That's fairly unusual, and I suggest doing a compression test, just to (hopefully) eliminate internal mechanical issues.

Yes I made a mistake #1 & #4 spark plugs are light tan and #2 & #3 are whiter.

It is cooler today and the car bucks less when the engine is cold with the new spark plugs but the buck isn't eliminated when the engine RPM is under 1,200 RPM and the engine is warmed up. The bucking is always a low RPM event.

The whiter spark plugs in old cars indicates a lean mixture or an air leak. I haven't been able to see live data on my Innova 3120. I hope up-dating it causes it to work as new or maybe the Innova is too old to work on a 208 vehicle OR maybe that is why it was sold.

RE: compression test in the plans when I find a compression tester with a long hose that fits down in the spark plug wells. I assume one pulls the fuel pump relay and disables the ignition coil pack.

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Originally Posted by OG-Lou

... RE: compression test in the plans when I find a compression tester with a long hose that fits down in the spark plug wells. I assume one pulls the fuel pump relay and disables the ignition coil pack.

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I didn't bother disabling the coil pack. All I did was pull the fuel pump relay and then just let it stall out.

I haven gotten to the compression test yet. I had several other things to do that had time limits.

I think my air intake temperature error P0113 code was due to me not getting the wiring connector pushed in all the way or starting the engine with the wire off. I cleared the code several days ago and it hasn't reset.

My air bag light has been on.

I did order a MaxiScan 903 Bluetooth OBD2 OBDII code reader. I think I will have it in 2 weeks. I bought the low price reader with the idea of buying something that might be able to much more later after I learn a few more things about OBD-2 and all of the optional modules on recent cars. I am investigating what type of scan tools can be had for under $600 to $800.

Things are more complicated since I worked for a car dealership back in 1986. I will admit to wanting tools and being able to use them properly even if it isn't all that practical or cost effective. OTH, if I pay someone to code parts so the car's computer to recognize the new part after a few times, it might pay for the advanced scanner cost.

I reconnected my Innova 3120 today and found the freeze frame data for a P0340 code that showed up again yesterday that didn't reset for 2 weeks.

freeze frame data Innova 3120 closed loop; load 26.6; coolant 183f; short term fuel trim 0%; long term fuel trim 5.4%; intake manifold 8.5 HG; timing 1*; intake air temperature 89f; throttle 13.3; engine RPM 866; MPH 33.

I might have been in neutral or had the clutch pedal to the floor getting ready to change gears or approaching a stop sign when the code was set. The strange thing is the car is almost back to running normal with only an occasional buck.

From what I read the difference in fuel trims might be an issue OR is an issue in 60% of driveability issues.. This is my first experience with fuel trims. I have years and years of experience with carburetors, rich-lean conditions, partially blocking the air intake to richen the mixture and/or adding some form of extra fuel to test for rich or lean conditions. I watched several "fuel trim education videos" but I do not claim I know what I am doing. Right now, learning a few basics is where I am at. I didn't have anything to see if the STFT changed and the videos I watched indicated a problem if a fuel trim was over 10

Over the winter my 10 yr old battery died so I charged it without disconnection the + or - cables. I also might have used jumper wires to start it. One friend said if he uses his car to jump start another car while his donor car is running it messes up his onboard computer/s.

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Originally Posted by OG-Lou

... I am investigating what type of scan tools can be had for under $600 to $800. ...

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That price range is WAY more than even the very best OBD realtime reader would cost (around $200 should be the top price). There are proprietary tools available which are quite a bit more expensive, however those are auto maker-specific and have no generic capabilities, and typically are purchased by the better shops who can get the required payback out of them.

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... I reconnected my Innova 3120 today and found the freeze frame data for a P0340 code that showed up again yesterday that didn't reset for 2 weeks....

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Nothing in the freeze frame data that you posted looks like a red flag.

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... The strange thing is the car is almost back to running normal with only an occasional buck. ...

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Given that the vehicle sat for quite a while, you might consider giving it a good 'Italian Tune-up' or two. May not eliminate the bucking, but won't hurt to give it a try.

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..From what I read the difference in fuel trims might be an issue OR is an issue in 60% of driveability issues.. This is my first experience with fuel trims. ...

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Fuel trims are fairly simple and straightforward. Ideally the Short Term FT numbers should fluctuate rapidly between small positive and negative numbers. Our Aveos typically stay inside of a +5 to -5 range, regardless of RPM. Long Term FT is similar, except that the rate of change is much less (constant numbers for longer periods of time). Anything outside of these patterns indicates some type of problem exists.

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... Over the winter my 10 yr old battery died so I charged it without disconnection the + or - cables. I also might have used jumper wires to start it. One friend said if he uses his car to jump start another car while his donor car is running it messes up his onboard computer/s.

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Although I've seen this same thing posted on other sites, I've never had a problem myself or know of anyone else personally who did either. But I also wouldn't doubt that it's a possibility.

I used 3 more scan tools in the $200 price range. None show any codes for the SRS air bag light being on and no other codes are present, not even a camshaft position code. I was wondering if the P0340 code needed to be set only after a drive cycle was completed or could be only set after xyz miles were on the emission test sequences was completed.

The last code reader was a Harbor Freight ZR13 and it showed the short term fuel trim changes quite a bit along with the O2 sensor voltage changing a lot too. so I guess that part of the emission system is working as designed.

I borrowed a compression tester but it didn't work correctly. It let out the pressure on its own. The compression might have gotten up to 90# but it dropped to zero really fast. I bought a compression tester from Harbor Freight. It had 3 long hosed adapters. I think a compression tester with a shorter hose might read a few pounds higher. I only came up with 130# on all 4 cylinders. The first stroke gave me over 90#. All 4 spark plugs were out, the fuel pump relay taken out and the throttle pedal all of the way to the floor. I did the compression test with a warm engine and did not add any oil to do a wet test.

I was reading a 2009 Aveo thread and that person has 125# to 130# of compression. Here on the Aveo forum I saw a compression test with something like 175#, which seemed on the high side when compared to what I found on engines 25+ years ago.

I compared the old marks I made on my old timing belt and sprocket marks with where the extra marks are on the new timing belt and everything matches up. I have the timing belt covers off for the third time looking for something I didn't align correctly. I am tempted to remove the new timing belt. I already have another timing belt I could put on and see if it makes the compression readings go up. With the marks where they are in my introduction pictures, I don't see where a newer timing belt would make any differences. It seems like a waste of time to change the belt again. I haven't ruled out replacing the belt a second time but it doesn't seem practical with the marks being lined up.

I talked to a mechanic that worked for a Chevy dealer. He said the rural dealership where he worked at had an Aveo customer with a problem/s that lead to the dealership finally replacing the engine after replacing a bunch of other parts and nothing improved. Later, someone found an ABS code or service bulletin and once the ABS issue was fixed the car instantly ran normal. Another story I read that had a P0340 code and the car did not have a cam position sensor position part. The problem was a bad coil ground. In addition, I read a story where the crank sensor was flaky but the car had a P0340 code. I suspect a lot of miss diagnosis taking place because of the lack of proper testing, limited knowledge, limited proper equipment, lack of time or wanting easy answers, and the tremendously complicated emission systems.

I have the car up on jack stands and I see my two remaining 10 yr old OE tires have small bulges in them. They still have 3/32 of tread but they have to go. I bought 2 used like new tires and I have a tire changer and a tire static balancer. Surprisingly the 10 year old TPMS sensors still work well. I use a set of 4 winter tires so the OE tires do not actually have 51K on them but something near 40K is possible.

My 1951, 1958, and 1966 Chevies were much easier to diagnose. It was do they have spark, fuel and compression and those 3 things were relatively easy to determine.

AVGUY, I had several auto parts guys say never have your engine running while jumping a no start car. Some say it is OK if your donor car is NOT running. I know from my GM auto training classes heavy draw electrical devices create internal spark called or related to what is called Transient Voltages that can go over 200 volts. In a starter the brushes arc/spark and that creates a high voltage. It makes sense to me because we did some tests in the GM classroom. I work on computer type circuit boards and wear a ground strap so i don't zap the integrated circuit chips.

I found the meaning of an Italian tune-up. I never heard that term before.

"Go out and thrash it (UK expression) a bit = Italian tune up!"

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Originally Posted by OG-Lou

.... I only came up with 130# on all 4 cylinders. ....

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That is WAY too low for a first gen Aveo. My '05 compression was 200 dry, and I'd expect at least 190 for any first gen engine in decent shape. You've said it runs well, and you did the testing correctly, so I'm suspecting that your compression tester is not making a good seal in the spark plug hole.

Thanks AvGuy, yes 2 compression testers that gave low readings puzzles me. The Harbor Freight compression tester when coupled with an adapter hose is about 18" long. I have a 40 year old Snap-on compression tester but I couldn't find it. I tend to think I can remember when I last used it. I need to get things back in to my tool box. With the extra tools I bought in the last 10 years, they come in plastic cases and I don't have room for cases in my tool box so I keep them in various places. I got a kick out of fixing up bicycles and bought a bunch of bike tools. Maybe I have too many tooks OR I need to be better organized.

Good news, My Aveo is running much better. Here is what I did yesterday and today.

I took the top timing belt cover off and the crank pulley off again. I watched or read over 20 web articles about timing belts, sprocket alignment procedures and sprocket tools that have alignment marks so only an idiot could get the timing marks miss aligned. I did my cardboard cut out tool again (new cardboard) and every thing lines up. My marks are dead on so that can't be the problem.

With the battery out of the tray and the air filter housing removed, I saw a ground wire group behind each headlight, I loosened them and then tightened them.

While the battery was removed, I think I did a reverse Italian tune-up. I turned on the dome light to drain any charge in any capacitor that is connected to 12 volt system.

After reading and watching some videos of bad grounds on spark coils giving a P0340 code, I loosened and tightened the bolts on my coil pack.

I watched some videos about drive-ability issues so I decided to remove the throttle body and clean it with "throttle body cleaner." I read the ingredients of carb and choke cleaner and the throttle body cleaner had about the same ingredients. Throttle body cleaner is $2 more than carb & choke cleaner but I didn't want to take a chance so I went with the throttle body cleaner. I tried Mass air flow sensor cleaner but that didn't remove much of the black crud next to the tube going to the EGR port and on the back side of the throttle plate. I didn't move the throttle plate very much, just enough for the cleaner to flow around the throttle plate that was all but closed.

When I took off the front tires to remove the crank pulley I saw each tire had a bulge, so I replaced both front tires with some used tires I already had. That eliminated a wobble in my steering wheel when I was traveling around 15 MPH.

Why the car runs better?
Number 1, I am going to credit the better running to draining the electrical system(reverse Italian tune-up) when I removed the battery and turned on the dome light. I wonder if the computer remembered the problems the non copper spark plugs seemed to cause. The engine starts quicker and does not crank as long as when the engine was bucking.

Number 2, maybe loosening and tightening the 2 body grounds behind each headlight had something to do with the car running better but I loosened and tightened 3 or 4 other grounds, which some were between the battery ground and engine block, and other body grounds.

Number 3, maybe the crud on thew back side of the throttle body caused an imbalance in the low speed fuel and air control.

Number 4, could an out of round shake the engine enough to create a false crank sensor signal?

I may have things fixed or maybe not. The next 2 weeks or the completing of a test to pass emission certification should give me a clue. I don't know how many miles it takes to qualify for that inspection.

Some of what I did doesn't make logical sense so "your mileage will vary" (results will be different) if anyone tries it on their car.

After watching more videos of synchronization and timing parts past 2 AM this morning, I saw a video of ' scannerdanner ' using a lab scope comparing the time signals from different components. It was related to late spark timing but the idea might work for the crankshaft signal when compared to the camshaft signal.

Laying in bed for a bit this morning I thought maybe when the engine bucked, the ECM interpreted the crankshaft rotating at one RPM and the camshaft rotating at a different RPM so the ECM created the P0340 fault code.

Number 5. So getting rid of the platinum or what ever spark plugs, cleaning the throttle body (the bucking was under 1,500 RPM) and draining the electrical system, may have all contributed to the car running better OR it could only have been one thing I did caused the car to run better.

One thing for sure is the code doesn't mean that actual part is bad but means the ECM didn't receive the signal as it was set up (PID) in the ECM. Maybe a fault code is triggered if one or several signals fall outside an expected variable values.

https://www.youtube.com/results?sear...=scannerdanner

The P0340 code is back a week later after driving over 125 miles and the freeze frame data looks normal to me. The car runs well so I erased the code.

I bought a Bosch 1050 bluetooth dongle. It has live data for about 25 PIDs so once I learn how to use the device and learn where things are in the menu, I am going to remove cam position wire when the engine is idling and see if the P0340 code is triggered right away or try to determine if the error has to happen after some other event is completed.

If I was designing the cam position software, I would have the light come on the first or second revolutions of the crankshaft if the cam and crankshaft were out of synchronization. I wish I could do a crankshaft sensor re-learn but it sounds like a "Tech2 tool is required. Several stories I read said the aftermarket tools usually do not work (after 5 tries) and the people had to go to the Stealership to get the crankshaft re-learn to take hold. One guy on a Youtube video with a "Tech2" did a re-learn in under 5 min.

But I don't run the show at the manufactures and my paycheck is peanuts compared to the people who design this stuff.

Quote:

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Originally Posted by OG-Lou

... If I was designing the cam position software, I would have the light come on the first or second revolutions of the crankshaft if the cam and crankshaft were out of synchronization. ....

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I'd expect that as well, and it's entirely possible that's exactly the way it works.

Have you taken a look at the ground wires and the big battery wire going to the fuse box? You want to keep in mind that all of this OBD stuff is electrical, and is totally dependent on getting constant good voltage from the charging system. So any electrical 'blip', even lasting for just a microsecond, might be enough for the ECM to flag a fault, simply because it didn't get a sensor reading when it was expecting one. And the bucking that you've previously described tends to fit in with that possibility as well. Perhaps there's nothing wrong with your vehicle, other than an occasional, sporadic, and very momentary electrical interruption.

I'm not trying to tell you there's definitely an electrical issue with your Aveo, only that it's in the mix. In any case, checking the grounds is a highly recommended thing to do for any issue which hasn't been diagnosed as being something else. But if you've already done so, then sorry for wasting our collective time with this post.

OG-Lou, my check engine light came on this afternoon and then disappeared before I could even drive to Autozone for the code read- but P0340 showed up in the OBD history when they pulled it! Your dedication to this error is incredible, thank you so much for the intense writeup! I will be interested to hear what solves your problem and if my error comes back.

Avguy
I have loosened and then re-tightened every major +12 volt connection and every ground I have found. It still could be a possibility something isn't making a good contact.

I bought a Bosch 1050 blue tooth scanner and had to play around with it to get it to work the first time. I didn't find codes at that time but the P0340 showed up earlier in the week because I erased it 26 miles ago.

The next thing I am going to try is disconnect the cam sensor wire, start the engine and turn it off right away to see if that sets a P0340 code. Then I will know if the P0340 is scheduled to turn on the CEL right away or later after it happens 2 or more times.

Like a lot of other people, I thought the code meant to replace the part. I am getting it that the code is more about an electrical signal and not the actual part. It is a learning curve.

My battery voltage is higher running than was in the pictures I posted. Next I am going to test all of the fuses. I tried to re-connect my Bosch 1050 scanner and it shows it is paired to the tablet I am using but the app won't run to show current data. I have to figure out that out before I do anything else.

My other MaxiScan bluetooth scanner also won't deliver data to my cell phone, so maybe something I am doing isn't working.
I also bought a Harbor Freight Zurich ZR-13 that was used. So I have 4 code readers of various abilities to read data or not.


On another related topic, I bout a second cam sprocket timing tool kit. Like the first one, my second cam sprocket tool kit doesn't work on my 2008 engine although it was advertised to work on a 2008. So back it goes. It was only $20 so maybe I might see if some of the fixtures could be modified to work at least a little.

I read several threads about the air bag light and most of the stuff i read indicated everyone had to go to the dealership and have the air bag light" diagnosed with a GM dedicated TECH-2 scanner. I am going to look on this forum for GM TECH-2 threads and if it is about the only scanner that works on Aveos.

If I don't find enough answers I am going to start a GM TECH-2 thread. The original GM TECH-2's cost a lot of money and the updates cost money. Now they have clones that are up-dated to work on up to 2013/2014 vehicles and the tool kit with all of the accessories is less than $350. Several guys on the Corvette forum have the GM TECH-2's and say it is one of the best purchases they made.

Clone Tech2 purchased-Very pleased
https://www.corvetteforum.com/forums...y-pleased.html

J5, I had the CEL light come on and also go off for a couple of days over a month ago. After I turned off the CEL, i drove for about a week before it came back on. This happened twice.

I will emphasize what AvGuy said in one of his earlier posts to me. Measure the battery voltage at the cam sensor connector. Measure the resistance between the sensor ground wire and the battery ground. And see if there is some voltage ( ~2.5V?) coming from the signal wire of the cam position sensor when the engine is running. Look at my initial pictures to do the tests.

Like I said above and AvGuy said, the part might be bad but the computer only is interested in the electrical signal coming from a sensor. The part could be good but something is interrupting the signal before it gets to the computer.

How many miles on your car? And at what mileage are you in relationship to replacing the timing belt?

Quote:

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Originally Posted by OG-Lou

Avguy
I have loosened and then re-tightened every major +12 volt connection and every ground I have found. ...

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I should have specifically mentioned the ground that's connected to the starter motor, because that's the cam sensor ground. Did you check that connection and also as much of that wire as can be accessed?

AvGuy thanks for the reply. Yes, I did sort of check-retightened the ground wire/s by the starter. I say sort of because I loosened it a half a turn then re-tightened it with a little extra force.

I suppose to do it the right way I need to follow my GM training school practice I participated in back in 1963. That is to remove the wire, clean off any paint, grease or crud, brightened the area and the wires, then install a star washer (small raised point on the perimeter) and re-tighten the bolts. I used to do this with cars with slow cranking 6 volt electrical systems and it really made an improvement in cranking speed.

Right now I have 11 trips on the car since I cleared the P0340 code and it runs well with only a hint of an occasional buck if I lug the engine a little around 1,000 RPM, coming out of a traffic circle. I checked for soft codes and didn't find any. I still need to disconnect the cam sensor wire, start the engine one then a second time to see if the P0340 gets set right away.

I got my Bosch 1050 to function to what seems logical. It was indicating it was paired to my tablet but every time I selected "show current data" the tablet screen went to the bluetooth setting menu on the tablet. I now have screen shots and data for each of the 4 screens (12 data points per page) but a few data points are N/A for an Aveo. It is still a decent amount of current data.

I had some things to do (50 th wedding anniversary) so I didn't get time to investigate Aveo potential repairs or engage in any self training. The mosquitoes are getting bad-annoying in the morning and in the evening when I work on the car. Mid day I have a shade tree to work under. And my yoga and bicycle rides all take time. I now poor excuses if a guy wants to "stay dirty," which is "Eric the Car Guy's" motto when he closes a Youtube video.

Can you post what the short and long term fuel trim patterns are, both at idle and while driving?

AvGuy, I have the STFT and the LTFT data but only at idle right now. I can do the road test numbers later. The cats or dogs or both peeed on the dining room carpet over the winter and with the warmer weather it just started to smell so I took the 6 X 9 carpet and hung it over the fence and pressure washed it. All of my wife's animals came from a rescue shelter and some of the rescue animals have problems because they were mostly neglected.

About a week ago I bought 2 used code readers at a pawn shop. A Bosch 1050 and a Harbor Freight Zurich ZR-13. I took pictures of the data screens for the Bosch 1050 and wrote down the engine data at idle. Today I did something similar but used the Zurich ZR-13. I am going to make a separate thread about the 3 scanners I have after I update the scanners to show what each scanner does when connected to my 2008 Aveo 5. I am severely tempted to buy a clone GM Tech-2 for $350.00. Yes, I can be a tool junkie and I admit it.

This afternoon I connected the Zurich ZR-13 and found 2 additional codes under the Chevrolet enhanced menu. I am not going to do anything to the car right now but I will be investigating some more things later. The ZR-13 is the only scanner that I found the Chevrolet enhanced menu on. I will look if my other scanners have an enhanced menu option.

This is what was displayed on the Chevrolet enhanced menu screen of the ZR-13, but the CEL/MIL is NOT on.

1.P0016 Crankshaft position - intake
Camshaft position not plausible

Possible causes Mechanical timing fault (stretched timing chain or damage timing chain tensioner) ........ more at
https://www.autocodes.com/p0016_chevrolet.html



2.P0650 MIL control circuit
Possible causes Faulty Malfunction Indicator Lamp Bulb Malfunction Indicator Lamp Bulb harness is open or shorted Malfunction Indicator Lamp Bulb circuit poor electrical connection Faulty Engine Control Module (ECM) ....
more @ : https://www.engine-codes.com/p0650_chevrolet.html

My P0016 code and my low compression numbers indicate my cam sprocket and crank sprocket timing marks are not aligned properly.

Here is more information about a P0016 code
https://www.obd-codes.com/p0016

Looking at the pictures I took that are on the first page of this thread has me puzzled. I even made marks on my old belt and sprockets, counted the teeth or slots between the marks, and re assembled the timing belt components so the installed parts were in the same location as thew original parts.

I bought the first and second timing belt tool set hoping it would fit/work and eliminate the process of visually aligning the 3 timing marks. Too bad the toothed spacers that go between the cam sprockets are too thick to even get close to fitting between the sprockets. Both tool kits might work on a 2009 with VVT.

The red plastic parts with notches that fit in the camshaft sprocket groves would nave been a way to exactly determine if I aligned everything properly. Too bad that part of the tool kit is too wide for my engine. Each side of the red notched spacers has an alignment notch that you match up.
https://www.amazon.ca/Engine-Timing-.../dp/B01M7OR7DU

Well, now I'm scratching my head about a couple of things here. First, off with such low compression, I'd been assuming something wasn't right with the compression tool that you had been using. But if there's a timing issue, and compression is really 130 on all four cylinders, then I'm not understanding how your Aveo could be running basically ok. I guess the final verdict will come in when you redo the timing belt.

The other puzzling thing (to me) is why one reader is able to read that P0016 but the other one cannot. Reading DTC codes is basic functionality and even the most inexpensive reader needs to be able to do that correctly. I wonder if that code is 'pending', and being ignored for whatever reason by the reader that isn't displaying it.

It will be interesting to see what happens next, after you have another look.

AvGuy, I have read and watched videos about scanners and it keeps popping up that some scanners read certain codes and not other codes.

1. I see there are about 5 protocols for data readers, so one tool might have a higher ability to read certain data. I watch scanner videos of scanners priced over $1,000 in side by side comparisons and often the guy doing the video says which scanned does what type of diagnosis better or worse on what model of vehicle.

2. Maybe I don't know how to use each scanner's total abilities. I will admit to starting out that I saw code readers as tools to replace parts and clear codes. Past that I didn't know what a STF trim or a LTF trim was or what the terms meant. I only found the P0016 code by playing with the ZR-13 menu and pressing buttons or making selections on the menu screen to see where it lead. I am guessing my Innove and Bosch 1050 don't have an "enhanced manufacture code" menu, so no codes from those scanners.

BTW,the "enhanced manufacture code" is different than global OBD2. I am guessing all of the other 4 scanners I connected to the 2008 Aveo were on "OBD-2 global" mode only. I stumbled on the "enhanced manufacture code" because I was trying to read why my air bag/ SRS (supplemental restraint system) light was lit on the instrument panel. After trying to get an air bag / SRS code all the other scanners and the ZR-13 scanner read was "unable to establish communication ......" which seems common according to the many Youtube videos I watched. Even the expensive ($800) scanners didn't do some SRS codes.

Right now I am of the opinion that my best choice of scanner would be to buy a GM Tech-2 clone from China for ~$350. I own a 2001 Buick LeSabre (no problems with the car) so that would give me a tool to do crankshaft re-learns on both vehicles. At $125 + for each relearn (if required) I would almost have the GM Tech-2 paid for. BTW, with a GM Tech-2 tool, a crankshaft sensor re-learn takes 4 minutes with the right tool.

Several years ago my speedometer quit working so I took my Aveo to the dealership. They gave me an estimate for $500+. I bought a used speedometer head for $50, it didn't fix anything. Next I bought a $14 speed sensor that goes in the trans-axle. Problem solved. I took the speed sensor apart. It had as small coil of wire and a tiny magnet attached to the shaft that is driven by the speedo-gear that spun around to pulse the coil of wire. I don't know the wave form type without looking it up.

Average Dealer price to replace a vehicle speed sensor (VSS) $312 to $490 and I did it for $65 including a $50 mistake.

VSS from eBay cheapie $8 now to $15, $52 JC Whitney, $76 GM, and up to over $140 in a few cases.

I sold a friends 2009 Aveo with 29,000 miles. Another friend had a 2009 with 33,000 miles. 2 local dealerships said they wanted to buy the cars becausethey had low miles and they had buyers for "cream-puff cars. I went to the dealer because they said they might pay close my asking price. I get the song and dance about how Aveos have a bad reputation and was offered some ridiculously low price. My friend (unknown to me at the time) got the same call from a different new car dealer. Bottom line, both offers were for around $1,00. So besides charging way too much for repairs and wanting to pay unreasonably low prices for a trade in, I think "stealership" fits some new car franchises.

On my friends 1997 Buick an independent shop wanted $70 labor to change 6 out in the open spark plugs. Other reasons I do my own work and struggle through the process sometimes is because of above examples.

Back to my situation. I watched several videos with P0340 codes ( Camshaft position (CMP) sensor) where the root problem was the Crankshaft Position (CKP) sensor. Why the miss diagnosis? Mainly because the DIY mechanic didn't have the expensive scanner or lab scope to look at the digital pattern on a scope screen, of the electrical signals coming from each sensor. Cars got a bit more complicated since my first "line mechanic" job in a larger repair shop.

I bought a used ECM ($65) and a cheapie crankshaft sensor($15) just in case. I would install the parts but both need to go through a reprogramming-re-learning process so I am holding off changing any more parts.

I live in a good size town but the next anything to the north and east is 50 miles away. Past those towns to the north and east any help is even further away, so break downs mean being prepared and self sufficient to a degree. having extra parts is somewhat normal in my circle of friends.

summary to my 2008 Aveo from a DIY perspective:
1. I am off a tooth on my timed belt but the pictures and the marks on my old timing belt say I am dead on.
2. My crankshaft sensor has something wrong with it or it needs to be "re-learned" or replaced.
3. The compression gauge I use registered low.
4. I don't have the right tools or all of the knowledge I need to fix the problem the first try, maybe even more tries, but i didn't quit trying.
5. I keep posting to solve my problems and to show other how they might be able to fi their own car.

I just deleted a double post?

I have to re-register if I want to save most post I try to save. Is there a time limit after I check in to make and save a post?

Quote:

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Originally Posted by OG-Lou

How many miles on your car? And at what mileage are you in relationship to replacing the timing belt?

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Thanks, OG-Lou! My airbag light also came on around the same time and has stayed on, I have not taken it to the dealership to be diagnosed.

My mileage is at 94k and I replaced the timing belt and water pump about 500 miles ago.

J5alive, if that was your first timing belt replacement, you got lucky. On some of these cars the timing belt breaks as soon as 50,000 miles. The owner's manual said to replace the timing belt every 60,000 but I did mine at 50,000.

I have been reading a boat load of forums and read a few places that if the battery voltage gets low, the computer remembers the low voltage and the SRS (air bag light) goes on. But, cars vary so much this might only apply to a few models. Seconly, there is a lot of guessing going on when a person doesn't have a scanner with the right software. Scanners typically say (detects xyz and abc codes in MOST or MANY cars. Most and many leaves big gaps in what a scanner will find.

The government made the car manufactures incorporate what are called "Global Trouble codes" that are emission related. These codes show up on low priced scanners. Special manufacture codes and other codes (not required in the OBD2 requirements) are not in low priced scanners so they don't show up unless you have a more detail capable scanner.

I saw a camshaft sprocket aligning tool made by "MV Tools) on a foreign language Aveo repair video. The video shows a good shot of tensioning the timing belt, which isn't that difficult. Out in the open where it is easier to see how it is done. I don't speak or understand Spanish so I don't know what the guy is actually saying.

https://www.youtube.com/watch?v=XbMDEIEHn1k

The tool first appears at @1:30 and is clearly visible @1:36. I used a couple of search engines and Googled but I didn't find the manufacture. I found what I think was a Mexican company selling the tool for 295 MXN = $14.31 USD and another 200MXN=$9.70 USD I suppose for shipping.

https://laredotools.com/i-aveo-mv-tools-(solo-en-web)

Does anyone have any idea where this tool might be for sale in the USA?

Up Date on my P0340 code and hidden code P0016

I checked the compression again with a different gauge and got 170 to 175 PSI. Just for kicks, I did the compression test with a 3rd gauge and got something to what I got several months ago, which was 140 to 145 PSI. It makes me wonder how accurate some gauges are. All 3 compression gauges were new or almost new.
I was watching a Honda timing belt video and saw that the camshaft sprocket marks to synchronize the timing belt aligned with the top surface of the cylinder head and thought that should applied to an Aveo. I took off the timing belt cover and the valve cover. After rotating the crankshaft to align the camshaft sprocket marks, I laid a bicycle spoke across the top surface of the hear. The end of the spoke was right next to each camshaft sprocket mark so the timing belt job I did over a year and a half ago was done correctly. So what was causing the bucking at low rpm under partial load?
I looked at the belt I installed and the part number wasn't the same as what was listed at Rock Auto. I put on a Gates 76127 I bought with a timing belt kit over a year and a half ago. Rock Auto's part was a GATES T335. Both belts have 127 teeth so the belt most likely wasn't the problem causing the P0340 code that only occasionally turned on the "check engine" (MIL) light. I recently bought the GATES T335 belt so I installed it just because I found it odd I couldn't find an application listing for the Gates 76127 belt.

After the timing belt was installed and tensioned and before I installed the camshaft sensor, I used the bicycle spoke to verify the correct timing of the camshaft position in relationship to each other and the crankshaft and notch by the oil pan. (see pictures). I was installing the replacement cam sensor I put on 1.5 yrs ago and saw that it could be moved a little towards or away from the center of the exhaust camshaft sprocket, so I moved it to the center of the sprocket all I could, thinking the more area of the sensor that the sprocket would pass, the stronger the camshaft sensor position signal would be sent to the computer.

pictures failed to load 2X. Maybe in the next post? 8 more tries=nothing. file size 92k
Just picture a pointer stick laying on top of the head with the pointer touching the cam sprocket timing notches and everything aligns on the intake and exhaust cam sprockets like they are suppose to when the parts are installed correctly.


I buttoned everything up, cleared the generic P0340 and GM special P0016 codes and took the Aveo for a short road test. I was pleasantly surprised and didn't have the slight bucking I have had for the last 6 months.

I do not think the problem was the timing belt part number because the timing marks all lined up with the 76127 belt. My guess is placing the cam sensor closer to the center of the exhaust cam sprocket influenced the camshaft position signal to be stronger so the computer could correlate both the camshaft position signal and the crankshaft position signal to fire the spark plugs at the optimal time and add the optimal amount of fuel.

The P0340 is a general camshaft position error signal and the P0016 is a factory special code indicating the cam and crank signals are not correlated or paired correctly.

The car starts quicker and I had only one slight hesitation under low RPM at moderate load during a 10 mile test run.

During all of this trying to figure out what is the root problem, I bought but didn't need 1 camshaft sensor, 1 inlet air temperature sensor (I didn't have it plugged in all of the way and got a code) A timing belt, pulleys, water pump kit (which I did need and installed at 50K). The other thing is I watched a lot of videos about timing belts and I watched a lot of videos about scanners, lab scopes, and how to use those pieces of equipment. I did buy an $80 Bosch 1050 dongle that works with a tablet or smart phone but only paid $20 used along with a used $199 Harbor Freight ZR13 for $80 at the same time.

The Bosch 1050 has some nice features, comes with several generic codes/capabilities for 1 vehicle but to use it on other cars requires an extra fee. It also requires an extra fee to do some/most ABS and SRS codes on each car or additional car. The ZR13 does more than the Bosch 1050 but not all that much more. The ZR13 found the P0016 code the other scanners didn't find. I also have an older Innova scanner and it only finds some codes.

What also captured my interest was the videos about the General Motors "Tech-2" scanner (used to cost ~$3,000) and the Chinese versions for $300. The Tech-2 was discontinued in 2012 but it had all or most of the problem solving software in the machine. The newer+2012 GM MDI has to be connected to the factory website to do most things where the Tech-2 had the solutions inside the unit stored on a memory card. The connection fee for 3 days for the MDI cost $65 for 3 days and I don't know what dealers pay for the year but it is more than I want to spend.

Well that is all well and good, Tech-2 or MDI BUT it doesn't stop there. A person sometimes needs a "lab scope" which is a precision device that reads voltages and time in great detail. To use a lab scope, a person should have access to other people's scope patterns, which are available but require a subscription=$$ to determine if your pattern on your scope matches other good patterns or shows signs similar bad patterns on other vehicles.

The short story, I think my car is fixed and all it took was moving the camshaft sensor closer to the center of the exhaust camshaft sprocket's center.

Pictures still do not load. Maybe I can make the file size smaller. Anyone know file size limits? I think my pictures are 3.5MB.

I also want to put up some pictures I took of the Bosch 1050 diagnostic screens and some details about the Harbor Freight Zurich ZR13 scanner.

Has anyone used or bought a "Tech-2" scanner. A bunch of guys on a Corvette forum have their own Tech-2 and said they wouldn't be with out one. Re-coding key fobs and doing a few other diagnostic procedures has paid for the $300 Chinese version of the scanner. Not many guys have the MDI because of the connection fees and most have pre 2014 Corvettes or other pre 2014 GM cars and trucks.