Quote:
Originally Posted by shiv@vishnu
The dip is caused by boost control. It's an issue called "integral wind-up" that happens during a low rpm, high gear pull. During low engine speeds, the DME is unsuccessfully trying to reach the boost target. So the integral component of the pId system adds full positive correction. When boost target is finally achieved, the DME still has all this positive correction that it cant get rid of quickly enough. So boost overshoots for a moment. In the BMW, this causes a throttle closure and a big recovery dip. So nope, it has nothing to do with AFR, timing, etc,. Just boost control.
Shiv
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Quote:
Originally Posted by atlharry
It takes 1200 RPM to correct a boost overshoot?!?! I find that hard to believe.
I'm not saying you're wrong... it's just hard to believe... Are there any datalogs to support that?
Edit: I'm sure you do. Can we see them?
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This confirms that black e was right. Its a boost over shoot. He was/is suppose to have a full write up of his finding from his dyno results today.