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Close Open Loop STFT Issue

Practical Reflash Tuning

Discussion and questions related to the course Reflashing

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I'm tuning a Golf V GTi with ECM Titanium and Alientech KessV2. I tried to rescale the MAF as per the video tutorial. I can manage to tune the STFT and low load 2500rpm and the best to +/-1%. However during the ramp run on Dynapack Dyno, the STFT is still keep adding fuel instead of staying at 0%. No matter what target AFR i have set at the AFR request Map, the trend of the AFR is still almost the same with the Dyno O2 sensor reading. Say i have set all loading points at high load to 0.85 Lambda, but the actual lambda was always goes down to 0.78. no matter i set the AFR request to 0.95, it also goes back to 0.78 with larger STFT compensation value.

Is there any idea whats going on? But the LTFT always at 0 or -0.8% no matter at high load or low load close loop. And i cant find fuel status PID shown nothing about close loop and open loop.. I'm using Plamer Dash XL for logging

I have attached the MAF map for your reference. yes its a bit different from the ECUTek Protocol

Attached Files

I'm not sure how much help I'm going to be able to offer as I've had very limited experience with VAG reflashing. From your description it sounds like the engine is running in closed loop permanently (which is possible with a wideband sensor) and hence over riding your changes. I'm not familiar with the software but I'd be looking for another target lambda table to adjust - Are there any other open loop or closed loop lambda target tables available? From my understanding the ECU also models EGT and can modify the commanded/final lambda target based on this calculation if it deems necessary. The tricky bit is that depending on the complexity/thoroughness of the software you may not have access to all the maps you need to adjust.

VAG are known for their hidden maps ! (sorry, I had to :P )