A4 1.8T load or torque interventions

by **mitkoenchev** » Wed Sep 23, 2015 1:18 am

Hi guys, I believe I have a problem in my tune and I can't solve it from a long time ago. It's expressed in mild to heavy vibrations in the cabin at about 3000rpm. Vibrations are harder in higher gears and lower intake temps (<45 deg C).
The car is a 2002 1.8T A4 Quattro, 150bhp. So far I've done a 2.75" exhaust, hybrid K04, custom 3" intake (still with stock MAF :oops: ), return type fuel system w/4bar FPR, S3 injectors, FSI coils, etc. FMIC will be in very soon.

I tried tuning some maps in different ways to see where's the source of the problem, but nothing helped and I still have no idea. So far I've tried different settings for KFMIOP/IRL, KFKHFM, KFZWOP/WOP2, KFURL, numbing ARMD, maxing out KFMIZUFIL/OF and HBN, lowered DIMX (underboost "solves" the problem), "softening" boost PIDs. I have the vibrations even with little underboost (30mbar) and actual load about 10-20% under requested. The only thing that helps is limiting load to about 155@3000rpm, which I don't like, because I've seen much higher loads in this rpm range without problems.

I've made a lot of logs and I observed that when I have vibrations I see some ignition timing oscillations, especially zwsol oscillating up towards zwopt. I tried lowering KFZWOP/WOP2, but I think I got slight throttle cuts, although the vibrations were gone. Another problem I have is I can't log mibas (I use ME7 logger), as I don't have it defined in my ECU file. So maybe this is torque intervention, but I think my torque model is OK, from what I understood after reading the funktionsrahmen more than a dozen times.

In the attached log with a few runs, where the first one is OK and the second has moderate vibrations in the cabin. I hope you'll help me understand why I have this issue. I can attach my bin if needed.

Many thanks in advance.

by **mitkoenchev** » Wed Sep 23, 2015 1:24 am

And here's more logs. In the 22.9.15 log (I tested lower KFURL values at 3000&3500rpm) I have no interventions in run 1, hardly noticeable ones in run 2 and strong vibrations in run 3. The other log is OK only in the first run. I also attach some graphs from the log in my previous post comparing the two runs, where the first one is OK and the second has the issue in question.