PLEASE help me out with this weird misfire problem.....
Thread Starter
TECH Addict
Joined: Dec 2001
Posts: 2,337
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From: Auburn, AL
PLEASE help me out with this weird misfire problem..... Alright, below 3000 RPMs, my #6 cylinder does not fire. It is getting spark and fuel. Above 3000, #6 does fire, and #2 does not. I thought it was valve springs, changed the springs and went back to the stock cam, same deal. Both cylinders are getting spark and fuel. Could this be a bad crankshaft position sensor? Is this something that reflashing the computer back to stock could fix? Also, the Ltrims on Bank 1 are -5-8% always, depending on RPM. On Bank 2, they are +14% until the car goes to closed loop (I think, it is always when the car is about halfway to 210 on the temp scale) and then the Ltrims go to +25%, I have no air leaks, I think it is just the oxygen the computer reads from the misfiring cylinder. Any clues would really help me. I have to get this car running right soon! Thanks!
Re: PLEASE help me out with this weird misfire problem..... First: Your Lterms on bank 2 are caused by the misfire. The fuel is not getting burned in that cylinder, so there is solid O2 hitting the B2 O2 sensor. The extra oxygen causes it to indicate higher.
Second: Misfires shift. The cars method of pinpointing the cylinder that is misfiring is sketchy (at best). As result, as the RPMs get higher, the misfire will start to "wander" on your scantool. Stick with the low RPM misfire. Most likely it is that cylinder that is having the problem.
Third: Back to the basics. Change the plugs. Change the ignition wires (borrow a buddies if possible). Swap the injectors from side to side and see if the misfire moves (if it does you know it is an injector). Swap coil packs (again try to borrow someones) and see if the misfire moves. The point is to change/move as much stuff as possible (within reason.... no #2 wire to #4 cylinder) to see if you can get the misfire to follow it. Blow out your fuel rail while your at it (to get any gunk that may be blocking the injector.
Fourth: If that doesn't do it, start moving up the line as a last resort. Harnesses, PCMs.....
Good Luck
Second: Misfires shift. The cars method of pinpointing the cylinder that is misfiring is sketchy (at best). As result, as the RPMs get higher, the misfire will start to "wander" on your scantool. Stick with the low RPM misfire. Most likely it is that cylinder that is having the problem.
Third: Back to the basics. Change the plugs. Change the ignition wires (borrow a buddies if possible). Swap the injectors from side to side and see if the misfire moves (if it does you know it is an injector). Swap coil packs (again try to borrow someones) and see if the misfire moves. The point is to change/move as much stuff as possible (within reason.... no #2 wire to #4 cylinder) to see if you can get the misfire to follow it. Blow out your fuel rail while your at it (to get any gunk that may be blocking the injector.
Fourth: If that doesn't do it, start moving up the line as a last resort. Harnesses, PCMs.....
Good Luck
Thread Starter
TECH Addict
Joined: Dec 2001
Posts: 2,337
Likes: 0
From: Auburn, AL
Re: PLEASE help me out with this weird misfire problem..... Okay, thanks for the ideas. I've moved injectors around, changed plugs, and swapped wires/coils around, but I'll try it some more. Thanks!
