Knock when letting off throttle.

I have finally been able to stop all the KR during acceloration, and now finding that when I let off the throttle during normal driving, or wot runs it showing KR.

I would assume since the ltft are negative that I should drop timing in that range?

http://www.purplegto.com/files/krdecel.png

I've seen my car have KR at seemingly impossible times, 75 on the freeway up a slight grade on cruise. I wonder if in the quest for mileage they didn't just run the timing way up and let the KR take care of it. Make a MAP comparing timing to airflow with the displayed data being knock retard to see the cells where you have problems.

Ira

Quote:

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Originally Posted by Ira

I've seen my car have KR at seemingly impossible times, 75 on the freeway up a slight grade on cruise. I wonder if in the quest for mileage they didn't just run the timing way up and let the KR take care of it. Make a MAP comparing timing to airflow with the displayed data being knock retard to see the cells where you have problems.

Ira

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Funny you should say that, I flashed this morning, reset the ltft's and did a nice little 60 mile loop around charlotte nice and easy with no WOT runs. Then I see this little guy pop up and wondered why.

Just like you were saying it was a slight incline and a small downhill right before it with cruise on.

Making a MAP of that now:
I can even use my new BLANK PID ;)

Another trick is to place the cursor along the tip of the onset of KR in your scan and then open up your corresponding *.tun file and observe the highlighted purple cell on the spark table... your cursor on the scan file is referencing the highlighted cell in your spark tuning table. This method is probably more convenient if you have an isolated knock instead of multiple instances of knock.

See here.