Misfire on cylinder 3 after head r&r due to overheat - Maintenance and Repair Forum

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Misfire on cylinder 3 after head r&r due to overheat
Thursday, November 21, 2013 3:09 PM
So my girlfriend's sister ran her 2.2L 2001 Sunfire out of coolant and drove it ~10 miles overheated. It ran like crap and had coolant in cylinders 2 & 3. We yanked the head, checked it, and it was warped 0.012". Had it machined flat, re-installed it with new gasket, headbolts, water pump, oil change, thermostat, plugs, and wires. It fired right up but ran rough, figured it just needed to be cleared out so ran it at 3k for a while till the smoke went away. Changed the oil again and started it back up, still ran rough. Figured out cylinder 3 is NOT firing at all. Check spark, ok. Checked compression, it struggled to get up to 120 psi, but the rest of the cylinders were right around there too. Leakdown test showed it was leaking a little out the intake valve, as were the rest of the cylinders, and they were all leaking past the rings pretty good (don't recall numbers but they all held 40-50 psi out of 75...). We yanked the head again, lapped all the valves, installed new valve stem seals, and put head back on with new gasket. Started it up again (less than 4 hours after deciding to pull the head off). Same issue. Swapped spark plugs around, switched plug wires with #2, pulled injectors and watched them spray while cranking (they all "looked" the same), still no fire on cylinder 3.

I know it's getting fuel in there because the one time I decided to check for spark, fuel sprayed out of the spark plug hole and ignited in a large fireball right in my face lol.

Any ideas or anything else I should test? It's low on compression, but it's not much lower than the other 3 are, and I'd think it would at least fire a little bit but at idle when I pull plug wires 1 at a time, I can unhook cylinder 3 and nothing changes at all. No drop in idle or anything. I'm stumped!

Re: Misfire on cylinder 3 after head r&r due to overheat
Thursday, November 21, 2013 3:46 PM
Coils and ICM are on the side of the head. Maybe when it got hot they got hot and went bad?



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