ctuinstra
Goblin Guru
We have always had a bit of throttle bounce that ends up in a vicious cycle of ON-OFF surging. Typically, it seem like it gets started (but not always) from a little bounce in the foot where you abruptly press the pedal and then quickly let off. The car then surges forward some and then back, this causes your foot to bounce again and the cycle continues and once it starts, you can't really stop it unless you let off completely, push in the clutch, or just floor it. At least this is what happens in our car. I've been able to reduce it by playing with the torque management, softening the shocks a bit and better control of the foot.
But tonight it was very cool and dry with the air density being especially high and it was just horrible. Every time I took off, I really had to be careful so as not to start the jerking again (especially with war-torn roads we have around here from this past winter). So this lead me to try a few things knowing it was a really good day for testing this.
I enabled the dynamic airflow all the time and reduced the predictive calculations. I believe the ECM is trying to predict the airflow and getting wrong and starting a bad oscillation. I set it as follows in the Airflow - Dynamic - Dynamic Airflow (for the P12 ECM):
This way its using more of the VE tables and it's filtered and smoothed out more than the pure MAF. I think that there could be a reverberation in the airflow across the MAF when using such a short intake tube from the filter to the MAF sensor. Just my thought, I don't really have much proof. The logging data shows everything bouncing at that point and it's hard to say which came first.
Either way, I took the car back out for another drive and WOW! What a difference it makes in the drive-ability! It's so smooth. There was one large bump and I could tell that I bounce the throttle and it surged once and then is stopped. It's never stopped before. I could tell there were many times where it could have had the issue, but it didn't.
I checked the logging data and the ARF is spot on, my VE tuning is still very good. LTFT were at 0.8! And the STFT were always correcting up and down as they should be.
You can see here the White is the pedal and the red is the RPM. There is a dip here and a bad bounce in my foot to the right. The RPM never really moved.
Very happy with the way it drives! I was wanting to do this for a long time but thought it was best to stay with the factory settings. But running off the VE table is so much better.
But tonight it was very cool and dry with the air density being especially high and it was just horrible. Every time I took off, I really had to be careful so as not to start the jerking again (especially with war-torn roads we have around here from this past winter). So this lead me to try a few things knowing it was a really good day for testing this.
I enabled the dynamic airflow all the time and reduced the predictive calculations. I believe the ECM is trying to predict the airflow and getting wrong and starting a bad oscillation. I set it as follows in the Airflow - Dynamic - Dynamic Airflow (for the P12 ECM):
This way its using more of the VE tables and it's filtered and smoothed out more than the pure MAF. I think that there could be a reverberation in the airflow across the MAF when using such a short intake tube from the filter to the MAF sensor. Just my thought, I don't really have much proof. The logging data shows everything bouncing at that point and it's hard to say which came first.
Either way, I took the car back out for another drive and WOW! What a difference it makes in the drive-ability! It's so smooth. There was one large bump and I could tell that I bounce the throttle and it surged once and then is stopped. It's never stopped before. I could tell there were many times where it could have had the issue, but it didn't.
I checked the logging data and the ARF is spot on, my VE tuning is still very good. LTFT were at 0.8! And the STFT were always correcting up and down as they should be.
You can see here the White is the pedal and the red is the RPM. There is a dip here and a bad bounce in my foot to the right. The RPM never really moved.
Very happy with the way it drives! I was wanting to do this for a long time but thought it was best to stay with the factory settings. But running off the VE table is so much better.