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Author Topic: logging with vagcom  (Read 3860 times)
sam
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« on: August 24, 2016, 03:20:16 AM »

hi ive been lurking in the background for a while now (mainly because I cant get my head around anything to do with mapping lol)
however a friend of mine is having lots of trouble with his big turbo 1.8t audi.
the issue is the more boost the car makes the more it starts to misfire.
its a 2.1 stroker, agu head, cams, gtx30 etc etc 1st and 2nd gear are fine but at the top end of 3rd its starting to misfire from 1bar of boost and @1.5bar it wont go past 4500. me7.5 (originally started life in a tt but its in a old 80 now)
its been to speciliasts and they are claiming something fundamentally wrong but no guidance as to what the issue or how to figure it out.
sounds to me like it is going mega rich but without a wideband afr gauge we cannot be sure...
so, how do we go about logging to figure out whats causing the issue? which fields are worth logging with vagcom? or am I better of with another programme for logging?
any help would be much appreciated.
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corradovolksb
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« Reply #1 on: August 24, 2016, 08:03:19 AM »

It sounds to me like spark is blowing out due to too large of spark plug gap when cylinder pressure is high under load.  I have a buddy with a big turbo 1.8t a4 I did the tune for and he had the same issues above 18psi the engine would misfire.  He gapped the plugs to .025 and the misfire went away. Give that a shot.
As far as logging goes your best bet is to use me7logger and ecuxplot to view the logs. It has much higher resolution than VCDS and you can log way more variables.  If you want to stick with VCDS log mvb's 2,3,20,115 and then do another log with mvb's 31,33,15,16
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2000 Nogaro blue S4 Stage 2. VAG for life.
sam
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« Reply #2 on: August 25, 2016, 12:57:16 AM »

Thanks very much. Will try plug gaps first
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nyet
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« Reply #3 on: August 25, 2016, 10:03:46 AM »

Plugs, coilpacks etc.

Don't need a logger to diagnose and fix misfires.
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ME7.1 tuning guide
ECUx Plot
ME7Sum checksum
Trim heatmap tool

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
sam
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« Reply #4 on: August 25, 2016, 02:07:32 PM »

It's had new plugs twice in last few weeks (coilpacks have been replaced for new genuine items(all 4) wiring inspected etc etc) new crank sensor etc
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