Mysterious lean issue

mmisch

Active Member
Oct 22, 2022
68
9
The Netherlands
Hello,

I'm currently still checking what could be wrong with my car. (1.8t auq)

Fuel pressure is 2.8bars, fpr works (shoots up to 3 bars when vac line disconnected)
Also tested while revving, spikes to 3 bar when demanding extra fuel (as it should)
NO vacuum leaks

Vcds tells me in mvb 032 and 033 that idle fuel trims is 0.4% and partial 12.x%

If i reset trims stft spikes up instantly to ~+15%.

Weird thing is: when going WOT fuel trims go -20 almost.

Basic things like pcv/dv/hockey puck etc all have been addressed and fixed.

MAF readings spike up to 180 g/s but only at around 4k rpm and at redline its more like 140 g/s

Car is also stage 1 chipped, i don't know where. I am planning to go stage 2 but wanted to fix this issue first

Here's one of the logs i have done
Click
 

mmisch

Active Member
Oct 22, 2022
68
9
The Netherlands
Guess no one here, but my car is ready for stage 2.
Even though my maf peaked around 180 g/s, it was misreading in the normal range of rpm (2/3000rpm)
Bought a GENUINE bosch (even though it was already replaced once), and fuel trims stay close to 0% (ltft +3% and stft -5% and not +15% anymore)

My car is fixed! :)
 
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