Here's the deal. 2004 Cavalier 2.2L Ecotec with 4-speed auto. 284,000 miles with a misfire. Cleared my CEL's, and let it run with a misfire to let the CPU start from scratch. P0300 came up, and shortly after, P0303 came up. I pulled the fuel rail, hung clear water bottles on each one, and turned it over. All 4 sprayed fine. But just to be sure, i put some 1999 LD9 high impedence injectors in it, and slapped it together again. Same thing. P0303, and it runs the exact same. I swapped the coil housing&ICM with a junk yard special, and i still have the problem on the same cylinder. Swapped the spark plugs with 2 different sets, and swapped the boots around in different orders, and it still misfires on cyl 3. I'm convinced it's a spark issue. I suppose it's possible the coil housing i bought was faulty, but just on cyl 3 seems too coincidental. or there's possibly a short somewhere? im running out of ideas here.
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Have you checked compression on that cylinder? I'm sure some googling could tell you how to test the signals coming from the computer to the ICM.
- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
Rented a comp tester. No compression on 3.
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Think you found your issue unfortunately.
"In Oldskool we trust"
yup. not too happy about it. paid $500 for it as it sits though so...cant complain. looks like it'll be driven with #3 injector unplugged, till she blows
its a shame. everything works on it, even the A/C
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I am not sure that this is a good idea to run the engine like that, unless you are prepared to throw it out soon.
At least take off the valve cover and have a look.
See this thread:
ecotec engine without valve cover
I am not suggesting that this is what happened to your engine, but having no compression is pretty drastic.
Good luck, Peter
definitely removing the valve cover tomorrow after class after seeing that post.
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Update. took valve cover off, and no signs of anything wrong. Everything looked fine. cranked it over while it was off, and looks fine. oh well, not really worth fixing for what it KBB's for, unless someone had an extra ecotec laying around...
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Well, I am going through the same thing, but it is on a close friend, daughters car. It had a misfire code on cylinder 2. I asked him to have it diagnosed by a professional shop, because it could have been several issues causing it.
I thought I knew what was wrong with it before I recommended he take it to a shop. I am old school DIY mechanic, not a professional...and just by listening to the engine idle I suspected it was a burnt valve
The shop came back with cracked head, warped head or blown head gasket, and low compression..Well a burnt valve will cause low compression, cracked head will cause low compression, blown head gasket between two cylinders will cause low compression on both cylinders...so I thought I would investigate it further
I then took the car home... 04 cavalier ecotec 2.2 DOHC misfire at idle, not felt much above 800 rpms
I did a dry compression test and If I remember correctly I got 72 psi, and the wet test didn't change that value, so at this point i'm thinking head problem.
I got out my cylinder leak down compression tester and set it up, made sure all other plugs were in, and pumped 100psi into that cylinder, and got a 38% leakage blowing out the exhaust pipe. I located the exhaust valve that was having the blow by, then got permission to pull the head, and saw that burnt valve
Now I am in the process of putting it all back together, after a complete valve job, ect, ect
I guess I am typing all this because you could do the same procedures I did on that cylinder, and maybe you can figure out which end is giving you the no compression
good luck!
Everyone should wrench!
