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

[Tw1tcHy]

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!

[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.

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).

[Tw1tcHy]

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).

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!

[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.

[Tw1tcHy]

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.

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.

[avguy]

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.

[Tw1tcHy]

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

[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.

[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.

[Tw1tcHy]

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.

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.

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.

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!