Author Topic: Strange stuttering while driving with constant speed with a Porsche 944 Turbo  (Read 192 times)

Offline pikard

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Hello guys,

I have a strange problem with my car. It happens almost at about 1600 rpm. While I am just trying to hold the speed the car starts to stutter.
You can download the log file here:

And here a screenshot:

The vems data:
Creator=VemsTune 1.5.57 (2018-01-04)

First I disabled the EGO correction but it does not solve it.
Next try was to disable the fuel cut and resume but nothing.
After that I played with the MAP filter in the ECU calibration but I had no improvement.

It happens in the 1600 rpm area only. Everything above is fine.
Sometimes it helps to turn the ignition off and on and the car runs fine.

Any ideas?

Thanks in advance

Offline GintsK

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Seems you drive on too retarded ignition for that load point. No? When engine gets degree more, it gain power and go in cycle back - forth.

Try add ignition there. Probably at that point you want 20...30deg. You can avoid steep Ignition table by retarding ignition with MAT/TPS table at low throttle openings but keep high values in RPM/MAp ign table. It helps for driveability. 

Second thing to try is to change Injection angle. In 720 cycle there is one point where something like this happens.