Mechanics

CHEVY P0300 RANDOM MISFIRE

1999 Chevrolet Cavalier

Engine Mechanical problem
1999 Chevy Cavalier Front Wheel Drive Automatic

Getting P0300 Random Misfire code. Car idle very rough and stalling. Very difficult to accelerate. Car missing so bad it takes long time to get up to speed. Once up to highway speed it seems to run pretty well. Replaced plugs, plug wires and front CAT. Had coil pack checked and it was OK. Could the rear CAT cause this? When I first checked codes there was also a P0141 O2 Heater Circ Malfunction. AutoZone said only rear CAT has heater circuit. But once I replaced the parts above and cleared codes I'm just consistently getting P0300 code. 2.2 L, 96,000 miles. Also unplugged MAF on intake hose and no difference or code. Could it be EGR, MAP, Knock sensor, rear CAT? Help?
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Gearwrencher
October 25, 2008.




Hi: Does it seem like the exhaust system is blocked in any way? Does it seem like there isn't much pressure coming out of the exhaust?

A clogged cat will cause a power loss, but I'm thinking something may be wrong with the injectors or crank sensor. Also, has the intake system (air filter, intake tube) been disturbed, damaged.

Let me know.
Joe

No, the exhaust seems to be flowing freely. I thought it was fuel related because I had checked all the ignition system. Worked on it awhile and was getting ready to give up. Then I tried an old school test. Started it up and pulled the ignition wires off the plugs one a a time looking for spark/arcing. 2 of the 4 produced no arc at all when grounded. The left side of the coil pack was defective (despite the test Ok from Autozone). Picked up a coil pack from local bone yard and all is well.
Now I am going to replace the gas tank. It is leaking due to rust. I would be interested in any tips you may have on how to replace it. Thanks for you reply.

Tiny
Gearwrencher
Oct 30, 2008.
I'm glad that you got it taken care of. As far as the gas tank, get it as close to empty as you can. Make sure the battery is disconnected. And get ready to be mad dealing with rusted tank strap bolts.

I wish I could give you better advise, but that is the reality of it.

If you ever have any questions, let me know and I'll be glad to do my best to help.

Joe
Positive feedback is appreciated.
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