foxySS Posted September 5, 2008 Report Posted September 5, 2008 Hey guys, I found out the source of my misfire headaches. Bad Magnaflow cats. In fact, the same ones that Chase melted down in his ride. Can someone tell me how to delete the rear o2's with EFI live? I'm running open headers until I get this problem resolved. Thanks Quote
Fireman31 Posted September 6, 2008 Report Posted September 6, 2008 I am glad to hear you finally figured it out, it didn't throw a code for the rear 02s at all? Thats strange, it should have at least thrown a P0420......... Quote
foxySS Posted September 6, 2008 Author Report Posted September 6, 2008 (edited) Well, I thought the cats were the problem... But low and behold it's still misfiring like a bitch. It looks like Justin turned all the 02 codes off last time he worked on my tune. The first time I drove it after no cats it ran fine, second time and there-on it got a p0300 epa and a regular p0300. This is the list of what I have done to troubleshoot thus far: - Swapped Plugs NGK TR55's w/NGK tr6's - Swapped Plug Wires and put back on stockers - Swapped Coils around - Did Compression Test and Leakdown test - Checked fuse box for bad grounds - Put in new Walbro 255 fuel pump - New Fuel filter - Seafoam in fuel system and PCV - Ripped Cats off - Put turndowns on open headers so front O2's aren't picking up pure oxygen. Things I have not done: - Swapped rear 02's with front ones (maybe they were bad because of cats backing up.) - Pulled injectors out to clean them - Put stock plugs back in Guys have any more ideas? Edited September 6, 2008 by foxySS (see edit history) Quote
foxySS Posted September 6, 2008 Author Report Posted September 6, 2008 (edited) bad injector? That's one possibility, but if it were injector related it would have to be more than just one to get multiple misfire. The only reason I haven't pulled the injectors yet is because I have to pull the blower to get to them. Edited September 6, 2008 by foxySS (see edit history) Quote
brobradh77 Posted September 7, 2008 Report Posted September 7, 2008 I wouldnt think so but i'm not sure...IMO if a cylinder isnt getting the fuel needed it should throw a code...buuut if your misfiring real bad wouldnt the plugs show it? Quote
foxySS Posted September 7, 2008 Author Report Posted September 7, 2008 Yeah, I've looked at them before and some of them seemed kind of lean but not terrible. The thing is it only really badly misfires at over 4K. So by the time I idle it and back into the driveway to pull the plugs they looks normal. Quote
Fireman31 Posted September 7, 2008 Report Posted September 7, 2008 Try replacing the MAF sensor, I have a feeling this might be the cause of your P0300 code...... Quote
foxySS Posted September 7, 2008 Author Report Posted September 7, 2008 Is there any way to troubleshoot the MAF besides using electrical contact cleaner? Quote
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