# Popping at idle...misfire?



## -RalleyTuned- (Nov 17, 2008)

Ever since I got my car put together it has had a popping sound at idle. Usually worse as it warms up, and more lately than before. It's a aeb 1.8t running stock 1.8t coils and wasted spark, MS2, 42# Bosch injectors, aeromotive for set at 42psi, stock passat pump + walbro inline pump. Also using ngk bkr7e plugs gapped to .025.

I have tried to mess with the tune and it hasn't helped, or made it worse. Running 13.8-14 afr at idle and have gone down to 10* and up as far as 18* at idle with no significant change. Running a 15* currently because that has been the smoothest so far. When doing some tweaking today I did notice it has a slight rich spike when it pops, which is why I am starting to think possible misfire. The car runs awesome other than that and is averaging 31mpg. Any thoughts?


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## Prof315 (Jan 5, 2009)

It _might_ be that the VAG coils aren't happy with waste spark at idle. Granting this is backwards of what I would expect, they ARE VAG coils  .


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## -RalleyTuned- (Nov 17, 2008)

It was the easiest/cheapest option when I did the swap, and all 4 had just recently been replaced. I have already considered swapping out for a good ol standard coil pack and 16v plug wires.


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## need_a_VR6 (May 19, 1999)

Which version coil and what drive circuit?


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## ValveCoverGasket (Mar 20, 2002)

dont know about the coil version but its got 4 individual BIPs firing in pairs for wasted spark.


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## -RalleyTuned- (Nov 17, 2008)

Thanks ved, I was hoping you would see this soon haha

I have no idea on coil version, but they were replaced in the past year. Is it in the part # by chance?


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## need_a_VR6 (May 19, 1999)

Ok so aeb 3 wire?


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## -RalleyTuned- (Nov 17, 2008)

yessir


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## need_a_VR6 (May 19, 1999)

That should be fine assuming dwell is in the 3-3.5 ms range. When it pops do you see lean spikes in the logs? Any one plug look different? Could be a coil going out.


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## ValveCoverGasket (Mar 20, 2002)

yeah is this something that developed somewhat recently? 
after we moved around the 4th BIP didnt it get all smooth again at idle for a while?


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## -RalleyTuned- (Nov 17, 2008)

It has pretty much always done it a little, it has def gotten worse as of this last month or so. When its warm it barely goes a few seconds without popping. I'll run a log at idle and see, I seem to remember rich spikes when it popped, and the rpm drops a little so it should show. 

I have been leaning towards a coil going out, I do have super random days when the car run terrible in boost. It's happened maybe 3 times since last march and its so random I never have my computer with me to see if its something obvious. 

It started to run really rich a week ago, but I found that it was running warm up enrichment from the 160* area of the warm up map. Set it to 100 instead of 107 and it all cleared up again. However that made no difference in the idle.


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## ValveCoverGasket (Mar 20, 2002)

yeah maybe check plugs and shut it down after it pops like paul said, might be able to catch one different looking plug that would lead you down the bad coilpack path...


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## need_a_VR6 (May 19, 1999)

Data logs, msq then start blaming VW coils is what I'd do.eace:


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