'06 Aveo cranks, but won't start. Running out of options

Hey guys! Been browsing around and you guys are an amazing resource! So I helped my friend with her '06 Aveo that's been parked for the last 6 months. Initially she had a coolant leak, then she began having ignition issues where she would start the car and it would crank, but over time take longer and longer to fire. After she got a flat, she parked it.

Fast forward to today. Tire is fixed, and the coolant leak was a heater hose (good god what a pain) and a cracked thermostat housing. However the ignition issue... So I tested fuel pressure, nearly 60 PSI at the rail (while she cranked it, attempting to run) replaced the battery with a brand new one and swapped the plugs and wires. Her valve cover gasket was replaced after the oil had nearly submerged all 4 spark plugs, so that was cleaned up. Didn't fix it however. I replaced the starter, still nothing. At this point I'm doubting it's the ignition switch, but possibly the CKP or CMP sensor(s)? Maybe a bad ECM? (No idea how to test for that). I refuse to let this car beat me, but it's doing a good job. All fuses were fine as well. We were able to get the car to turn on for a bit after jumping it from my car for awhile, but it died shortly after disconnecting the cables. During that time, the car was so weak that even flooring it she could only get the RPMs to around 1.5k. There's also no CEL, but she said it's been that way for awhile.

Not sure if I've left anything out, but tried to give you the whole picture. Any input is SERIOUSLY appreciated. Thank you for your time! :)

First question - did you spray a small bit of carb cleaner or sensor-safe starter fluid into the intake, to see if it would run on external fuel? (even though you checked the fuel pressure) Always important to make that simple basic test, in order to eliminate fuel as the issue.

Assuming it won't run with outside fuel; disconnect the battery, touch the cables together, remove the fuel pump relay and the spark plugs. Then have a helper crank it while you ground the plugs on the block, checking for spark. If there's spark, then a compression test is next.

But if there's no spark, check all of the grounds and B+ connections, including the fuse box and under the battery tray. If that doesn't fix it, see if you can rent or borrow a scope, in order to check the waveform of the crank and cam sensors. If you can't find one, at least check those sensor wires for reference, ground, and signal (which will be erratic).

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Originally Posted by avguy

First question - did you spray a small bit of carb cleaner or sensor-safe starter fluid into the intake, to see if it would run on external fuel? (even though you checked the fuel pressure) Always important to make that simple basic test, in order to eliminate fuel as the issue.

I should have done this, but I didn't think it would yield anything after I had tested the fuel pressure. I will definitely do this to be 100% sure. I had noticed her throttle body hardly seemed to open even when she was laying on the gas during a start up attempt, is that indicative of a problem, or normal for these cars? I'll also note that manually pushing it open more didn't have any discernible effect on startup performance, so I didn't think about it further

Assuming it won't run with outside fuel; disconnect the battery, touch the cables together, remove the fuel pump relay and the spark plugs. Then have a helper crank it while you ground the plugs on the block, checking for spark. If there's spark, then a compression test is next.

I did a similar test, but again, probably should have done it that way. I disconnected the #1 spark plug and hooked it up to the wire. I still had the battery connected and and had her attempt to start it. I could see spark from the spark plug. I did not have the fuel pump relay pulled though. I'll also add that I apparently didn't have the plug as grounded as I thought as I got a nice shock through the arm upon touching the insulation :(

Side note: I've never heard of disconnecting the battery and touching the terminals together for testing. What does that do if you don't mind me asking? And will the car still be able to crank like that, with no connection to the battery?

But if there's no spark, check all of the grounds and B+ connections, including the fuse box and under the battery tray. If that doesn't fix it, see if you can rent or borrow a scope, in order to check the waveform of the crank and cam sensors. If you can't find one, at least check those sensor wires for reference, ground, and signal (which will be erratic).

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I will see if I can find a scope. I'd considered swapping out both sensors anyway, although the cam sensor looks like a total pain.

And thank you so much avguy! I was worried this post wouldn't get any attention. I will definitely be giving these a shot and seeing where that takes me.

Beyond these, if we were to say everything checks out, sensors are good, we have fuel and spark, compression checks out etc, at that point are we just left with a bad ECM or is there anything else I've overlooked? I verified the timing belt wasn't snapped by having her crank the engine and watching the belt rotate through with no issues, and occasionally the car WILL start up, but only very rarely and after considerable effort and time after initially turning the key.

Thanks again man, seriously!

The whole bit with disconnecting the battery is to reset the learned portion of the ECM, because it's possible that the computer can shut down one or more cylinders when it sees lots of misfire. And if so, that would affect the spark testing results, so resetting the ECM eliminates that possibility. Touching the cables drains the caps and clears memory faster. Although I didn't mention it, the battery does need to be reconnected before doing the spark test.

That said, it sounds like there's spark, based on what you wrote. It would be good to check all 4 plugs, in order to be certain that all are firing, but I'd expect that spark is ok. So do the fuel spray test, and post back with the results.

Quote:

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Originally Posted by avguy

The whole bit with disconnecting the battery is to reset the learned portion of the ECM, because it's possible that the computer can shut down one or more cylinders when it sees lots of misfire. And if so, that would affect the spark testing results, so resetting the ECM eliminates that possibility. Touching the cables drains the caps and clears memory faster. Although I didn't mention it, the battery does need to be reconnected before doing the spark test.

That said, it sounds like there's spark, based on what you wrote. It would be good to check all 4 plugs, in order to be certain that all are firing, but I'd expect that spark is ok. So do the fuel spray test, and post back with the results.

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Very interesting! That makes sense, I would not have thought about ensuring the ECM was reset to ensure an accurate spark test result. Something tells me spark is okay as well, but I can't be certain. I'm hoping to be able to poke around the car a bit tomorrow, but will definitely have time this weekend to tackle it if not. I will absolutely be picking up some sensor-safe starter fluid and doing the fuel spray test.

What's curious to me is that we were able to get it to fire up once last night, about 2 hours before my thread was created, by jumping the new battery with my '98 Trans Am for awhile. Giving it some gas on my end and she was juuuuust able to get it started for a bit. I disconnected the cables and it died within a minute after having ran for at least 5 minutes. I wish I had run it longer like that to have a better idea of if that was a coincidence or not...

I will be updating you ASAP avguy! Really appreciate the help, I've scoured these forums and read some interesting stuff, and I hate to see the threads with similar problems go unfinished, so I fully intend on trying to make this detailed until it's finally solved so that way it can serve as a nice reference point for any owners in the future who have this problem.

One thing to keep in mind is these no-start issues can be caused by multiple things, which is why systematic testing is so important. In your case, the coolant leak brings into play a possible (badly) blown head gasket. Not saying that's the case, only that it's more likely than it normally would be. And that's the reason I suggested a compression test as the next step, assuming that it won't start and run briefly on external fuel. That test would either eliminate, or confirm an internal problem, and would take you quite a bit further down the diagnostic trail.

Well no luck with the starter fluid. Fuel is officially ruled out.

I tried to rent a compression tester but the store said they rented it out yesterday, so I'm still waiting on that, though I don't think the issue is a head gasket. Oil looks great, and from the 2 or 3 times we have gotten it running, no smoke and no overheating (since I replaced the heater hose and thermostat housing).

If the compression checks out, I'm guessing the next step would be to check the CKP and CMP sensors? I'm not sure how to get ahold of an oscilloscope around here, I'm thinking it'll just be easier to buy two new sensors and replace them and see if that changes anything. If it doesn't, then aside from the ECM I'm damn near tapped out of ideas

Were you able to check for spark on the other plugs? If all of them have spark, and with fuel being ok, then it's surprising it doesn't fire at least a bit each time you try to start it. So if you've confirmed spark, then definitely do the compression test. For that one you'll want to pull the fuel pump relay and all 4 plugs. Then keeping the gas pedal down to the floor while cranking, check each cylinder dry (without squirting any oil into them}. You should see compression numbers somewhere in the 190-205 range. Slight lower compression might be ok, but not too much lower.

Good spark basically confirms that the crank sensor is good (not for certain but nearly so), so IMO it would be a waste of time and money to hang one of those on. And a bad cam sensor should still allow it to start and run - sputtering perhaps, but at least something.

This is the list of troubles I had with my 06 over the years
1) Oil leakage from the valve cover into the spark plug holes
2) Check timing. Is the timing belt in good shape and does the marks line when the Cylinder #1 is TDC?
3) A Good solid energy source (electric). Is the battery in good shape? Are the ground wires connected properly? The 06 you can put a spark tester inline with the plugs.

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Originally Posted by avguy

Were you able to check for spark on the other plugs? If all of them have spark, and with fuel being ok, then it's surprising it doesn't fire at least a bit each time you try to start it. So if you've confirmed spark, then definitely do the compression test. For that one you'll want to pull the fuel pump relay and all 4 plugs. Then keeping the gas pedal down to the floor while cranking, check each cylinder dry (without squirting any oil into them}. You should see compression numbers somewhere in the 190-205 range. Slight lower compression might be ok, but not too much lower.

Good spark basically confirms that the crank sensor is good (not for certain but nearly so), so IMO it would be a waste of time and money to hang one of those on. And a bad cam sensor should still allow it to start and run - sputtering perhaps, but at least something.

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I was limited on time yesterday, so I didn't check the other 3, but I will out of due diligence. I'm 98% certain they're all sparking though, since every time we have gotten it to turn on, it ran smoothly with no misfires, and I've had scenarios where I've had plugs not work but the engine was still able to fire. Nonetheless, I will look into an inline spark tester like xintersecty mentioned.

I'm about to head to the store in a few and grab a compression testing kit, it should be back by now I'd imagine. I hope it checks out, or else she's going to have some bigger issues to face, though I have a feeling it will do okay, especially as this was a reoccuring problem for awhile that continually got worse. If it was a piston ring, I would think the problem would have been immediate and not progressed more over time. Same with the valves/valve seat, but I could be wrong.

And damn, if you're right about the sensors, then I may need to find a compatible used ECM that I can swap to test to see if that helps at all, because at that point I'm nearly stumped.

Quote:

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Originally Posted by xintersecty

This is the list of troubles I had with my 06 over the years
1) Oil leakage from the valve cover into the spark plug holes
2) Check timing. Is the timing belt in good shape and does the marks line when the Cylinder #1 is TDC?
3) A Good solid energy source (electric). Is the battery in good shape? Are the ground wires connected properly? The 06 you can put a spark tester inline with the plugs.

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Preach it on number 1 haha!!

I haven't checked the timing belt entirely yet, but I was able to see the belt when I had the valve cover off and had her crank it for ~20 seconds or so. Belt stayed taut and unbroken, though I haven't seen if it became misaligned. I can't see how that would happen, but my cars all have timing chains, so timing belts aren't something I've screwed with much. Even if the belt was off, wouldn't the car be running like crap every time we've managed to get it to start?

My instinct is telling me this is an energy delivery problem. The problem is the battery is brand new, and was swapped again for another brand new battery and still no go. New starter as well. I've been able to get the car to sometimes turn on by having my battery connected to hers and jumping it while she cranks for a very long while, and that's the only way so far. I feel like somehow enough energy is not being transferred from the battery to the starter to get it to fire like it should, but as far as how to test for that, how plausible that is, or how that could have even happened, I'm stumped.


Will report back soon with compression and spark results!

Well then.

Did an in line spark test all good. Did the compression test and, in order on each cylinder - 60 PSI, 55-60 PSI, 60 PSI, 80 PSI.

It was shortly after this that I rechecked the oil. It looked fine before, but after rechecking it and despite having looked fine before, the oil now looks like chocolate milk...

My instinct says head gasket naturally, but why does the oil look so poor after getting it running once?? When it DID run it ran fine, and how would this have taken compression out on ALL cylinders? We couldn't do the test with a warmed up engine of course, but no way it would have made a difference that huge...

The plot thickens :(

Stop overthinking it and bring it down to basics. You need fuel, air and spark for combustion.
-You have fuel pressure at the fuel rail
-You dont have anything preventing air from entering the cylinders
-You claim to have spark, on top of replacing wires and plugs
-You have compression on all cylinders

Some other things to think about
-Car has been sitting for 6 months. Its possible the fuel may just have gone bad?
-Even if you have a bad PCM, as long as you have fuel, air, and spark, you should have combustion
-Is the timing belt still in check?

Agreed, that's how I've laid it out to her to help her understand the problems she's having. We 100% have spark and fuel, yet it struggles.

We have compression on all cylinders, but hardly. Seems to me that the lack of comoression would be a good indicator of why it struggles trying to fire up.

Turns out the car has o my been sitting since around early July, which changes the timeline a bit. Just discovered that last night, (she's bad with dates it seems...), so I don't think it's gas.

I will be checking the timing belt out very thoroughly later today. I'm not sure how to know if the #1 piston is at TDC with the head still on, or if that's even possible with this car, but I'll figure something out.

What's blowing my mind is that now all of a sudden this oil is classic chocolate milk, indicative of coolant mixing. But good God for the head gasket to have blown enough that there's a leak in every cylinder for the compression to be like this... Doesn't seem right.

Compression is WAY too low, and explains what you've been seeing. I'm guessing the coolant was low for quite a while, and she repeatedly cooked the head gasket (and likely warped the head as well). You could do a leak down test to confirm it, but I don't think that's necessary in this case.

I didn't even bother with the leak down test lol. She swears she didn't drive the car much when it would begin to overheat, but I'm hoping like hell she didn't warp the head... If it's somehow miraculously just a gasket, then this should be good to go, but the fact that it's all 4 cylinders gives me doubts...

I began tearing into it yesterday. Only had 3ish hours or so, but I nerd to remove the coil pack and EGR mounts (easy), remove the bolts holding the intake to the head (fuel rail is already gone), and jack the car up on the front passenger side after removing the wheel to access the timing belt area and take everything off of that. That seems like the biggest pain in the ass left to do. Exhaust manifold is unbolted, I just need to get it off the studs.

This can't be over soon enough, but like I said, I'm seeing it through to the end! I feel like we're all in this together at this point haha

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Originally Posted by Tw1tcHy

... but I'm hoping like hell she didn't warp the head...

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Most of us DIYers don't have what's required to check for true, so you are going to take it to a machine shop, correct? It would be a major kick in the a$$ to reassemble, only to find it still has problems. Also plan on doing a couple of immediate oil changes, and a coolant flush, once it's back and running ok.

The one thing you need to cross your fingers (and toes) about is the effect of coolant dilution on prior lubrication of rings and bearings. The part about her running it for a while and getting worse over time sounds potentially ominous but, since there's nothing you can do about that, no sense in worrying about it.

Absolutely. I used to build high end GM racing transmissions (4L80Es, TH400s, Powerglides, etc) for 1-2000hp clientele (even two guys in the show Street Outlaws) and if there's one thing the racing industry taught me, it's that a machinist and his equipment are worth their weight in gold (or at least billet aluminum).

We have a good place around here that's fairly cheap that I will be giving a call for an estimate. If their pricing is too out of line, then I will just have her buy a refurbished head.

The oil looked fairly good the first time I pulled the valve cover off and I added a couple of quarts of fresh oil after replacing the valve cover gasket and we got it to fire up that evening for a bit. I guess it was at that point that the oiled became extremely dirty, because it looked like **** when I took the valve cover off again a couple of days later. I don't know why it happened so suddenly, or what exactly triggered all of this. I have never seen anything like this before, and after some of the things I've encountered, an Aveo was the last thing I expected to hand my ass to me so bad haha!

Do you know when the timing belt was last changed on this Aveo? If she doesn't know, or if it's been anywhere close to 60K, you might want to have her consider buying a new timing belt kit. The 4 part kits go for around $100, and it's naturally a great opportunity to do that work. Of course that decision depends on her finances, and also how long she would like to keep it, assuming nothing else major happens.

Are you buying the gasket and head bolts from Chevy, or do you have another good source?

When you just dove into the engine disassembly with no hesitation, I had a hunch about you having some type of significant auto background. I hope this lady understands how fortunate she is to have you working on her vehicle!

Forgive me , but how many miles on the engine ? If you send the head to a machine shop , you might as well ask them to see if it needs a valve / guides job . And , of course , if the head needs to be cut flat .

Yes , do the timing belt , coolant pump , and related parts , that comes in the kit .

Best of luck , :-)
Wyr
God bless

Could not find where to post a new Thread, Having starting Issues with my 2007 Aveo5. It Cranks but does not start, I was told to replace the Cam Sensor and the Crankshaft Sensor. Both of them I replaced, than I was told to replace the Alternator and to get a new battery which I did, and its still not turning over. After this I replaced the Spark Plugs, Coil Pack, and Spark Plug wires and still is not starting, I also replaced the 100 amp fuse which is attached to the Positive post on the Battery. All of the fuses are good, So Ive hit a wall and can not seem to figure this out.

Got fuel pressure?

It needs fuel , spark and compression . Find out which is missing .

It did not break the timing belt , did it ?

Wyr
God bless