P0300 Ugh!
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TECH Regular
Joined: Aug 2005
Posts: 455
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P0300 Ugh! First, I installed new headers about 6 months ago. Had a misfire on #7. Replaced ALL the wires with MSD and NGK TR55 plugs. Problem went away. 2 months later...problem is back. Replace plugs and one damaged wire.(clip was broken). Problem solved....
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
I've been periodically throwing that code also. How many wires would have to be bad to throw a "multiple" cylinder missfire code? I know one of my MSD wires has a bent metal connector and it doesn't click on very well. I thought it was on well enough not to be a problem, but now I'm not sure. 
Originally Posted by ChicagoTransAm
First, I installed new headers about 6 months ago. Had a misfire on #7. Replaced ALL the wires with MSD and NGK TR55 plugs. Problem went away. 2 months later...problem is back. Replace plugs and one damaged wire.(clip was broken). Problem solved....
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
Dude, i had this on my stock motor at 80k. Replaced all the plugs/wires, even the coil pack for #7 (the one that was "misfiring") It turned out to be my #7 piston rings were shot. Do/get a compression check and see what it says.
Launching!
Joined: Aug 2005
Posts: 213
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From: NWFL, AKA - Redneck Riviera
What about the fuel/air ratios? I had P0300 and raw fuel which was caused by two clogged injectors. This caused a cylinder (or two in my cae) to run lean, while the others run rich.
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Originally Posted by rd_ls1_z
What about the fuel/air ratios? I had P0300 and raw fuel which was caused by two clogged injectors. This caused a cylinder (or two in my cae) to run lean, while the others run rich.
This could be too, but when i had mine, i forgot to add that i also tried GM spec (read: expensive) injector cleaner, which was to no avail.
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Originally Posted by ChicagoTransAm
First, I installed new headers about 6 months ago. Had a misfire on #7. Replaced ALL the wires with MSD and NGK TR55 plugs. Problem went away. 2 months later...problem is back. Replace plugs and one damaged wire.(clip was broken). Problem solved....
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
Now, I have a multiple cylinder misfire. Car is backfiring (puff of smoke/raw fuel comes out when it does). Just filled the car up with 93 octane so..possibly bad gas? It's starting to get cold here in Chicago so don't want to be playing around with it TOOOO much. Any idears?
TECH Enthusiast
Joined: Jul 2005
Posts: 732
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From: Herndon, VA
Originally Posted by bshell
Are any of the plug wires touching the headers? They could be too close to the headers and are burning through.
