so heres the story behind it....03 cavalier...auto...75k
I started my car on saturday afternoon, made it to the end of the street and the CEL started flashing and TRAC OFF light came on. I turned the radio off so i could hear my car and it had a definite misfire....rough idle between 500-600rpm. Went back to the house, shut it off and popped the hood to have a look. I noticed that the cooling fan was running with the car off. I had driven it maybe a half mile and the temp gauge wasn't even to halfway yet. Limped it to autozone (<5 miles)to have the code scanned and i was told i had a misfire on cylinder 1. Got it back home, pulled the plug out, and i saw this:
The only time i've ever seen the tip completely gone was from the piston hitting it...which i'm pretty sure i would have heard/noticed. I had an extra plug laying around from the 05 cobalt motor i'm tearing apart. I put that plug in and it ran fine while driving it around the neighborhood. Got it out on the main road and it was still running fine until i got up to 3500-4000rpm and it started missing again, CEL and TRAC OFF light came on again. Took it back home, pulled the plug again and the porcelin part was sitting against the electrode. This proved at least that the piston wasn't hitting it.
I put a brand new DELCO iridium plug in it monday from the dealership and it has been running fine so far. However i haven't gotten the motor over 3500rpm in hopes that i can avoid ruining another plug until i can have it scanned at my buddy's dads shop to see exactly what is causing the misfire.
We're thinking that i possibly have an injector going bad or clogged which (FEEL FREE TO CORRECT ME IF I'M WRONG) i believe would cause it to run lean from not enough fuel....causing it to run hot (fan staying on)...or possible that there is something wrong with the ignition coil/module.
Has anyone else had this problem or something similar?
ANY HELP IS APPRECIATED...so if you have another idea of what is causing this, please let me know.
Edited 2 time(s). Last edited Wednesday, September 26, 2007 1:57 PM
The threads on that plug look WAY too long... are you sure your using the right plug? Maybee it's getting to hot. Man you lucky you haven't messed up an exaust valve yet.
I think that the fan automatically comes on when the car goes into limp mode (wich is what happens when the cel starts blinking) I dropped a cylinder on my 2.4 because part of my coil housing went out.. and when the car went into limp mode to keep it running.. the fan came on.
If an injector was running that lean, it would have thrown a code or fried that cylinder by now..
The missfire is being caused my the plug going out (obviousley)..... you need to find out why the plug is doing that first which scanning it prabably wont tell you.
If it only happens over 3k or so and runs fine before that... than there's something strange going on.
Pull the plug... turn over the engine until that cylinder is at TDC and shine a flashlight in there and try to see if there's any marks on the piston head.
Yeah those threads on the plugs seem kinda long. Whats kind of a plug is that?
i think that cylinder is detonating and blowing the plug apart..
thats the delco replacement plug from the dealer. i put it in back around march-april
Maybee you should go to Napa or autozone, and compare the plugs they have for your car to what you have. Although if you have those plugs in the other 3 cylinders without any problems, I would have to go with the cylinder being the problem and not the plug.
Pre-ignition (detonation) does sound like a probable cause.
I have the same problem with my gm SC kit. From 3000-4000 rpm I get some knock that doesn't log with HP. If I apply too much load it flattens the gap on the spark plugs. could it be bad gas?
Should I try an octane boost?
How did you fix it?
Is that carbon dust around the defective plug hole in the cover?
Also, is that an arcing mark on the long insulator to the plug?
Look at the difference between the faulty and good "holes"
Alont
we figured out the problem
cylinders one and four were both arcing pretty bad, so we replaced all 4 plugs and boots. runs fine now
