Another crank no start condition 04 Auto base

Hey fellow Aveo-ers?!?
I own a fun cheap little 04 Chevrolet Aveo its automatic (boo..) but its super cheap to drive, easy to maintain and I have to drive it (have a mandatory ignition interlock device). So I did some maintenance and repairs on the car over the course of a couple weeks, replaced head gasket and timing belt, put it all back together went to go start it and had absolutely not fuel pressure. I should probably let you know at this time I left the battery connected while performing the repairs on the vehicle I pulled fuel pump fuse so if I bumped ignition on it wouldn't shoot fuel into my open engine. First off I know should disconnect the battery before doing any repairs but as I previously mentioned the vehicle has and IID and the manufacturer recommends that the battery not be disconnect for a long amount of time as it can set off a false tampering signal or possible violation. Anyways, car would not start, when I turned the ignition on I noticed for once the engine light was not illuminated and the fuel gauge also didn't work. Plugged scan tool in and found no communication with the ECM, while trying to connect the check engine light flashes briefly, checked DLC pin 16 and found power, checked all fuses (underhood and I/P) including fuel pump and 2 fuses for ECM power, all checked out good. Checked power coming into ECM (Pin 1) and had full power. Thinking i've got a bad computer likely from not disconnecting power source and had something short out ecu. Anyone have anything similar? did some reading and seems like guys have had to replace these little control units before.

Compression test.

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Originally Posted by avguy

Compression test.

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Engine fired with starting fluid. I'm 98% sure its not a compression issue, I have a used ECM coming, will update.

Through an ECM at it, fuel pressure is back, got the CEL back, comm with engine through scan tool, fuel gauge and rpm signal while cranking and still won't fire up. Pulled spark plugs, they are in ok shape and not covered in fuel or oil. Checked compression, Cyl 1-135, 2-130, 3-140, 4-130. Compression seems low but engine was cold and should still be more then enough compression for one of these small engines to run fine. I'm wondering if maybe my timing is out 180 degrees? I used prodemand as a guide for timing marks and used what appeared to be marks, will take some pics later to verify. Anyone have anything else to give me an idea of what to test for? Should I be bugging the company of the IID??

My '05 compression was 200 cold, at 150K miles, so the compression in yours is definitely low IMO. I don't think it could possibly be off 180 degrees, but I don't know anything about the tool you're using. It sounds like one or two teeth off, but that's just a guess on my part.

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Originally Posted by avguy

My '05 compression was 200 cold, at 150K miles, so the compression in yours is definitely low IMO. I don't think it could possibly be off 180 degrees, but I don't know anything about the tool you're using. It sounds like one or two teeth off, but that's just a guess on my part.

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Pulled it all apart, made damn sure that cams were set right, intake gear on intake cam, set so notch is inward toward exhaust gear notch, same thing with exhaust gear and timing, set crank to notch at the bottom and verified #1 cylinder at TDC. It cranked and cranked and almost fired up for a second then stopped, put battery charger on car, cranked and cranked, oil pressure light goes out when cranking now so I believe it seems oil pressure while cranking. I also make sure to use the special aveo timing belt tool to set the water pump.

If compression is still about where it was before, then I'd suggest a leak down test to zero in on the problem. Perhaps something is wrong with the HG or some valves somehow were bent? Again, just guesses, which is why it's important to find out exactly why the compression is low.

Ok guys bumping this up. The car got put on the back burner for some time as I was pissed off and stressed about it. Anyways, replaced the ECU with the same part number, plugged it in, hooked battery's up, fuel pump immediately primed and I got pressure at the rail back, while cranking i've now got rpm signal and oil pressure on the dash and the check engine light does illuminate (non of these things were happening before with the toasted ECU). Compression test shows a solid 150psi all 4 cylinders across the board (did proper compression test this time). I've reset timing approx 4 times to make sure i'm dead on and i'm either dead on or 180 out, but i've tried it 4 times now with the exhaust cam at different marks. I also have spark from the coil. With the intake off and open, battery on a charger, car will still just crank and crank. It doesn't seem to want to fire with ether. I'm beyond my mind on this simple car. Please someone give me a hint, what am I missing??

I had intermittent crank no start problems, seems to have been a faulty crank position sensor after replacing a throttle position sensor (dealership suggestion under warranty) and the coil (third party workshop based on diagnostics). But seems unlikely to be the case given your previous posts.