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Engine Random Misfire?

Tiny
GEARWRENCHER
  • MEMBER
  • 1999 CHEVROLET CAVALIER
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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Saturday, October 25th, 2008 AT 9:19 PM

40 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
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...

These guides will help us

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

and

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Let me know.
Joe
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Sunday, October 26th, 2008 AT 12:27 AM
Tiny
GEARWRENCHER
  • MEMBER
  • 2 POSTS
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.
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Thursday, October 30th, 2008 AT 9:59 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
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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Friday, October 31st, 2008 AT 7:18 AM
Tiny
SRRHENOW
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET CAVALIER
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 12,000 MILES
Car starts and runs but not well. Plugs are burning clean. 300 misfiring code
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Friday, October 16th, 2020 AT 11:12 AM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
Hello,

First thing when was last Tune-Up? I would say 8 out of 10 times the plugs are the cause. Especially with 120k miles. With the newer (96 and up) the recommended first tune-up is at about 100k miles.

That is were I would start.

Then would check for Vacuum leaks.

Faulty EGR System.

Faulty or leaking Injectors.

Other possibilities are.

Crank Position Sensor.

Weak Coil.

Weak Fuel Pump or Fuel Pressure Regulator.

.
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Friday, October 16th, 2020 AT 11:12 AM (Merged)
Tiny
LOSCAUS
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET CAVALIER
  • 73,000 MILES
When you get to 45mph and 55mph the car will shake like a manual transmission when you need to gear down. Mine is an automatic. It runs good other than the missing or whatever you want to call it. We have replaced plugs, wires and coils. Nothing helps. Sometimes it don't do it but it's getting worse. The engine light nevere comes on, so we can't code it. Nobody seems to have an idea what it could be. Please help!
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Friday, October 16th, 2020 AT 11:12 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You sure the transmission is not slipping if not go to this link for more information:

https://www.2carpros.com/articles/engine-hesitates

and

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down these guides and report back.
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Friday, October 16th, 2020 AT 11:12 AM (Merged)
Tiny
CAN'TFIXIT
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET CAVALIER
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 125,000 MILES
I have a 98 cavilier running on #2  cyl. Cam timing &compression r good, plugs & coils have been replaced. Would low fuel press cause this?
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Friday, October 16th, 2020 AT 11:13 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test the crankshaft position sensor
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Friday, October 16th, 2020 AT 11:13 AM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Maybe ignition control module see diagram
Image (Click to make bigger)
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Friday, October 16th, 2020 AT 11:13 AM (Merged)
Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
Yep sounds like a coil pack to me to.
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Friday, October 16th, 2020 AT 11:13 AM (Merged)
Tiny
LSWIRTZ
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET CAVALIER
  • 4 CYL
  • FWD
  • MANUAL
  • 109,000 MILES
I keep cracking plugs on my third cylinder. Its right on the porceline. Small one inch crack very consistant same looking crack. Happens once every three weeks. New plugs and wires. Some one suggested the coil. But if you knew the set up on the 2.2 if the one was cracking wouldnt they both that are on that coil. Of course once the plug goes bad I get major missfire. Doesn't make any codes come up. Doesn't even register a missfire. Someone said while the motor is running spray water on the coil if you here poping or something something is wrong with your coil.
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
Coil test. I would also use a thread chaser to make sure the threads in the head are good, a loose plug can cause cracking. Another possibility is that the hole is cracked. This guide can help you test the coil.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Please run down this guide and report back.

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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
VILLELA22
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET CAVALIER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
I was selling my car some guy test drived it after that it didnt want to work I took it to get a diagnose they saud it was a misfire before that that I lost my key and broke the switch you think that could be the problem
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
BASSTECH
  • MEMBER
  • 236 POSTS
The misfire is more then likely related to the spark plug wires or ignition coils. You didn't say where you broke the key or which switch you broke, but if your talking about the ignition switch being broken, I don't think that would have any effect on the running of the engine.
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
JOHNNOBLE
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET CAVALIER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 221,650 MILES
In just the last 2 weeks my car started to jerk softly while driving on a major highway. I thought it was the transmission but then I remembered that AAMCO checked it out and said that there is no problem with it. So, this past Monday I had a tune-up but I still have this problem. I also took my car to a diagnostic facility and they said that my rotors and pads have to be replaced and also my front rims are bent?

I am confused :cry: Some people don't have alot of money these days
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
BKEFFER1791
  • MEMBER
  • 2 POSTS
I have this exact same problem. My cavalier has 129350 miles on it and when I keep it around 65 and higher it starts******** a little. I think its an engine or injector problem. I am going to change spark plugs, wires, and try to clean the cylinder heads if I really need to. I can let you know that helps.
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
LACY KOOIMAN
  • MEMBER
  • 2 POSTS
  • 1998 CHEVROLET CAVALIER
I was stopped at a stop light and when I pushed the gas to go my car made a sound like a back fire and like I had a flat tire but it wasnt neither and now it makes a chug chug chug noise and doesnt go very fast but no engine light comes on. Any idea what could be wrong?
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
It sounds like you have a engine misfire. If the check engine light is on, take it to a nationally recognized parts store and have them scan the computer. Most will do it for free. That will tell you what cylinder is missing and guide you in your repair. NOTE: IF you want, let me know what the code is. Some parts stores will sell parts just to do it. Also, some parts stores will help you install some parts.

Let me know what you find or if you need help.
Joe
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Friday, October 16th, 2020 AT 11:23 AM (Merged)
Tiny
LACY KOOIMAN
  • MEMBER
  • 2 POSTS
No engine light came on though so thats the only thing that confuses me, and the hot/cold temperature gage is not abnormal either. You still believe its an engine misfire? Are their any other possibilities?
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Friday, October 16th, 2020 AT 11:23 AM (Merged)

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