Question about 2004 Chevrolet Cavalier

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2004 Chevy Cavalier 2.2l is misfiring at idle speed

Code po300 on computer. Changed plugs and boots. Check coil pack. The car runs down the road fine as long as you give it gas. Let off the gas and it idles rough, nearly stalls. Heard it could be O2 sensor and throttle position sensor. How do i determine which one. Or if its that at all. Need help. Dont want to go buyin parts not knowin if its goin to fix it.

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  • lnbrowning Dec 30, 2008

    It had the code before changing plugs and boots. No change afterwards.I can take the vacuum line off of the evap solenoid and the engine smooths out. I purchaced a new solenoid but didnt help. Seems like not gettin enough vacuum to the fuel regulator. Checked all the lines for cracks and leaks. Checked and cleaned the MAS. No Changes. Checked Power terminal to the Evap Solenoid before I purchsed the new one. Changed Fuel filter.Check oil for signs of water from possible head gasket leak. It gets a little water in the air duct to the throttle body from steam?? Car runs perfect down the road. Just when you stop at light, the engine trys to stall. Do these cars have an egr valve? If so where are they located??? The car can run 100 mph no problem. No hesitations or lack of power. No accessive fuel loss. Engine doesnt miss at speeds above 900 rpm. Thanks so much for the advice.

  • lnbrowning Dec 31, 2008

    Have not checked ompression yet. What are the specs?

  • propmandan Jan 25, 2009

    1991 cavalier 3.1 rs. did it before, went away on its own. now doing it again. at operating temp it intermittently roams at idle (up to 1200 down to 500 - or 0) otherwise runs fine. dirty egr?

  • Rick Byrd
    Rick Byrd May 11, 2010

    if you had a P0300 random misfire before plugs and boots , did it have the same symptoms then ? and have you re scanned it after clearing the code and installing plugs ? if you had a bad TPS throttle position sensor you would most likely have a code for that , O2 sensor again most likely have a code , a vacuum leak would be a good reason for a random misfire yet work good off idle , a weak cylinder compression would effect idle . a dirty injector might work ok off idle but give poor idle results . vacuum leak, dirty injector has no codes , they require visual inspection and finese .



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I have a 2004 cavalier and had a po300 code bought all kinds of sensors and replace spark plugs and the whole coil assyembly the problem was the timing chain tensioner lost tension because of lack of oil changes the engine got all caked up with layers of muddy oil and pluged up the oil galleries and of course the timing tensioner causing the chain to jump a tooth after replacing chain and tensioner and cleaning the whole engine even the oil pump pickup screen the engne came to life again with no codes and runs like new my engine is a 2.2 ecotech

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Posted on Dec 30, 2008


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I am getting a po300 code i changed out the coils and still have a po300 code my car has a problem pulling off then seems to run good but still has a miss

still has a miss Larry, P0300 does mean misfire condition, but does not mean the coils were bad. Bad plugs,wires, injectors, coils, etc. can through this code.
Check the attached links, troubleshooting,instruction and guides, a lot of good info. Good luck .
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
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Misfire po300

Error Code: P0300
Random/Multiple Cylinder(s) - Misfire Detected
Problem Area:
Air Intake System leaking.
Fuel Supply faulty.
Injector(s) faulty.
Ignition Cable(s) and/or Spark Plug(s) faulty.
Ignition coil(s).Exhaust Gas Recirculation (EGR) Valve stuck/open.
Camshaft Position Sensor faulty.
Low compression.

Check Misfire Recognition.
Check Air Intake System.
Check Fuel Supply.
Check Injector(s) and Injector Sealing.
Check Ignition Cable(s) and Spark Plug(s).
Check Ignition Coil(s).
Check Exhaust Gas Recirculation (EGR) Valve .
Check Camshaft Position Sensor.

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Mis fire code po300 po68

300 is random misfire and 306 is cylinder #6, I would check the coil pack on #6. If it has separate coils per cyliner, swap the coil, see if the misfire goes to that cylinder. If it does replace the coil.
If it has three coil packs you can still swap the coils. If that doesn't fix your problem, then you will have to check the injector with an ohm meter. resistance between the prongs should be between 11 to 15 ohms. check another injector and they should be relatively close. Let me know
Good luck

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I have a 99 jetta 2.0 old body style with code po300 random misfire

Sorry have to be quick work time is here ,right slacken the exhaust /manifold down pipe and try that ,it will make a noise but try it in case the cat is partially blocked from where the O2 sensoir wanst working ,its a outside chance but worth a try

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Car jerks while taking off; changed fuel filter

get a scan tool to retrieve the dtc (diagnostic trouble code).
you will get a misfire code.
p0301 for cyl 1
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i can't recall if that engine has plug wires or coil on plug but if its coil on plug replace the coil corresponding to the cylinder misfire

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did you have have AV little idling for while if you had i'll set code too and bad gas.Is run fine?let me know

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I would've started with the coil packs, modules, boots and plugs myself. They give many problems on the quad 4s?.

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