need help with misfire on my 2.7t c5
#1
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need help with misfire on my 2.7t c5
hi, i have a 2000 audi a6 with the 2.7t. yesterday, it had a steady misfire when i got in it to drive it, but it went away after a few miles of driving. this morning i got in it to go, and same misfire. this time it wont go away and is a very steady misfire. also, after driving it about ten miles, i got home, shut off the car, and noticed a light trail of smoke coming from the drivers side wheel well. i noted that it was from the drivers side only. the power steering has been a little bit stiffer than normal in the past 2 days, but i dont see that being related to the misfire. i put the scanner on it and this is what i came up with.
16518 o2 sensor bank 1 sensor 1 no activity
17861 exhaust gas temperature sensor1 (g235) open short to plus p1453
16684 random/multiple cylinder misfire detected p0300
16689 cylinder 5 misfire detected p0305
17523 o2 sensor heating bank 1 sensor 1 short to ground p1115
16686 cylinder 2 misfire detected p0302
when i look at diagnostics i see that cylinder 5 is misfiring steadily/constantly, and the others for the most part do not misfire. i have tried moving plugs/coilpacks from cylinder 5 to 6, and misfire stays at cylinder 5.
help please!
16518 o2 sensor bank 1 sensor 1 no activity
17861 exhaust gas temperature sensor1 (g235) open short to plus p1453
16684 random/multiple cylinder misfire detected p0300
16689 cylinder 5 misfire detected p0305
17523 o2 sensor heating bank 1 sensor 1 short to ground p1115
16686 cylinder 2 misfire detected p0302
when i look at diagnostics i see that cylinder 5 is misfiring steadily/constantly, and the others for the most part do not misfire. i have tried moving plugs/coilpacks from cylinder 5 to 6, and misfire stays at cylinder 5.
help please!
#2
Pre-cat O2 sensors can and will cause your engine to misfire. I searched high and low for what was causing mine at the time and finally narrowed it down to the pre-cat driver side O2 after many people posted that an O2 would not cause those symptoms. Are you getting a flashing check engine light while driving? If so, don't. I'd probably start there since you are dealing with a random misfire on top of cylinder 5, but others with more experience may have greater insight based on the EGT code you're getting.
#3
AudiWorld Super User
hi, i have a 2000 audi a6 with the 2.7t. yesterday, it had a steady misfire when i got in it to drive it, but it went away after a few miles of driving. this morning i got in it to go, and same misfire. this time it wont go away and is a very steady misfire. also, after driving it about ten miles, i got home, shut off the car, and noticed a light trail of smoke coming from the drivers side wheel well. i noted that it was from the drivers side only. the power steering has been a little bit stiffer than normal in the past 2 days, but i dont see that being related to the misfire. i put the scanner on it and this is what i came up with.
16518 o2 sensor bank 1 sensor 1 no activity
17861 exhaust gas temperature sensor1 (g235) open short to plus p1453
16684 random/multiple cylinder misfire detected p0300
16689 cylinder 5 misfire detected p0305
17523 o2 sensor heating bank 1 sensor 1 short to ground p1115
16686 cylinder 2 misfire detected p0302
when i look at diagnostics i see that cylinder 5 is misfiring steadily/constantly, and the others for the most part do not misfire. i have tried moving plugs/coilpacks from cylinder 5 to 6, and misfire stays at cylinder 5.
help please!
16518 o2 sensor bank 1 sensor 1 no activity
17861 exhaust gas temperature sensor1 (g235) open short to plus p1453
16684 random/multiple cylinder misfire detected p0300
16689 cylinder 5 misfire detected p0305
17523 o2 sensor heating bank 1 sensor 1 short to ground p1115
16686 cylinder 2 misfire detected p0302
when i look at diagnostics i see that cylinder 5 is misfiring steadily/constantly, and the others for the most part do not misfire. i have tried moving plugs/coilpacks from cylinder 5 to 6, and misfire stays at cylinder 5.
help please!
My S6 had a misfire…the technician apparently didn't tighten the plug enough and it came loose…right around 30K miles ago the car had a low-mileage used engine put in it and new TB service, rest of rubber stuff, new plugs, etc. But the loose plug caused the misfire..I was just lucky the combustion didn't eat a hole in the aluminum head along the plug threads!
Last edited by SloopJohnB@mac.com; 07-19-2014 at 04:55 PM.
#7
AudiWorld Super User
And…how long have the plugs been in there?
Over 30K miles, change them.
There should be NO oil on the plugs…ok on the threads when you pull them out but not on the hot end. These things run dry as a bone.
Over 30K miles, change them.
There should be NO oil on the plugs…ok on the threads when you pull them out but not on the hot end. These things run dry as a bone.
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#8
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i have switched coilpacks between the 5th and 6th cylinder with no change...still a steady cylinder 5 misfire. when i shined a light in and looked at the cylinders the 6th is dry, where inside the 5th is wet looking...i took brake cleaner and cleaned off both the plugs, and blew them dry with air, still the steady knock on #5. the plugs im sure could be changed but i dont think they are my main problem as of now because of switching plugs between cylinders as well, with the misfire staying at the 5th cylinder. so should i go after 02 sensors now?
#9
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i also put the air nozzle down in cylinder 5 and shot some air in there to dry it out, a white cloud of (smoke) (dust)? came out, with a burnt smell. dont know if that is relavant.
#10
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It's not.