"Misfire" at WOT, or is it?>>
08-07-2008, 08:07 AM
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"Misfire" at WOT, or is it?>>
Hi there folks, I have not been here for quite a while, simply been too busy and the TT has been running uneventfully. Other fun endeavors such as moutnain biking and sailing keep me from fiddling with the car. Until about a month ago. Under WOT at full boost there would be an occasional SINGLE ignition "bang" almost like a backfire, just once. No fault codes other than CAT for which I will fit the spacer. Last week I did a few 3rd gear acceleration runs to get the misfire/backfire thump to repeat to see if a fault code would come up. Got it to hesitate 3x in one run and then just single hits in other runs. No fault recorded! Mixture settings are spot on. Car has 63k miles, plugs with 20k on them, original coil packs, 3rd MAF, no apparent vacuum/boost leaks, coolant sensor replaced 20 k ago. It does not really seem to be a misfire. In fact it reminds me of my old 1975 Ford Cortina, if the carb was bad a a flame spat back through the throat! I did a search on the subject but am still puzzled. Have not tried changeing out or unplugging MAF yet, have also not done a log on MAF performance yet. Thoughts as to what could be the cause?
08-07-2008, 08:14 AM
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when was the last time you checked the gaps on your plugs???>>
20k on plugs depending on which ones can cause a misfire or hesitation, especially when the weather is warmer...
It is best to check there first....if the gaps are fine, then i would say a coilpack is showing early signs of failure....VAG it to determine which cylinder is misfiring, more than likely it is cyl 2....
It is best to check there first....if the gaps are fine, then i would say a coilpack is showing early signs of failure....VAG it to determine which cylinder is misfiring, more than likely it is cyl 2....
08-07-2008, 08:22 AM
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no misfires while driving or at idle???? >>>
there needs to be load on the motor to get see misfires in most cases....
Cyl 2&3 are subjected to the most heat for the most part...
Cyl 2&3 are subjected to the most heat for the most part...
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08-07-2008, 09:00 AM
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20-21psi peak, I detuned the BM after the first time it thumped.>>
I also noticed on a long ( 5hr) drive a month ago that the fuel consumption was worse than normal at 27MPG with roof up, while normally it will return 28MPG or better.