2008 Aveo LS, Chugging/Rough Idle, No CEL

[avguy]

... Compression came back, all four cylinders were very close (1-3psi). ....

Even compression on all cylinders would be uncommon for a blown HG, unless the gasket was damaged evenly (which would be quite unusual). What were the compression readings? Did you remove the coolant overflow tank cap to see if there was any bubbling in the tank during the compression test? If not, do you have any other evidence of a bad gasket?

The 'white residue' could be something as simple as normal condensation which didn't have enough time to get burned off because the engine wasn't sufficiently hot long enough. It would be really disappointing to do the gasket, only to find out it wasn't blown at all, and not the cause of your performance issue.

[zaksglass]

There was some bubbling. I drove it a couple weeks ago after changing some ignition/intake parts, it ran smoother. Drove about 60 miles on the highway, and I burned coolant and oil.

The timing parts will be the first to come off. I had suspected the timing was off a tooth, but after burning coolant and oil figured it was the head gasket.

Edit: Forgot to mention that even though it ran smoother, I still had a rough idle and misfire, on top of burning coolant and oil.

[EAD15]

For what it's worth, several people have reported that platinum plugs have caused problems with their Aveo and better luck with regular copper and/or Iridium plugs.

It might be worth getting some new cheap-ish copper plugs to test

[zaksglass]

Got down to the timing components today. The front camshaft sprocket is off by two teeth.

[zaksglass]

Cylinder head came off today.

Head gasket had utterly failed - almost no seal left, it was pretty much bare metal.

Replaced gasket and got the cylinder head back on. Currently plugging things back in and replacing some other parts. Having trouble with a few vacuum lines off the battery side of the intake manifold, I'm not sure where they go.

[hexskrew]

Go to gmpartsdirect.com and look up the car and search around in emissions I think. They have exploded views of most parts. Saved me multiple times.

Oh and I definitely know about not using the Platinum plugs. They just cause our engine to run like crap. The last time I tried it misfired like crazy and stopped immediately after changing back to copper plugs.

[zaksglass]

Good to know thanks so much for the reply.

I'll dig through GMPartsDirect. Will also order copper plugs.

[hexskrew]

So how did it go?

[zaksglass]

It's all back together right now. New head gasket, plugs, wires, ignition coil.

Car cranks hard but will not turn over. Fuel pump primes and runs when the key is turned, so I'm not sure what's going on. Will look at it later today.

[zaksglass]

OK SO IT FINALLY STARTED AND RAN TODAY!!!!

Ignition wires were mixed up. Simple as that.

Car started, ran rough, CEL came on and I stopped her. Two codes, P2076 and P0303. I had mixed up the vacuum lines on the EGR Canister, simple as that.

SO NOW I JUST HAVE P0303, CYLINDER #3 MISFIRE. I'm at my wit's end with this car.