Knock Retard Question

[dennismc]

Last summer I had a 87 tune from BBP done and at the time Justin mentioned he noticed some Knock Retard and asked what gas I was running, which was Chevron, so I was a bit surprised being supposedly Top Tier and all. So now that I have an AutoCal Unit I filled up with 89 Chevron and Data Logged, it was showing a maximum knock Retard of 5.4 on the 1st log and 4.0 on the 2nd, is this considered excessive?

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That's pretty high, but it really depends on where in the rpm range it's doing it that really matters to the longevity of the engine.

[vettelovralexand]

I would think that that is quite a bit being on an 87 octane tune. You might want to check out a different gas station.

[kjhallex]

Try a different gas station and fill up with 93 or 91. It could be false knock.

[dennismc]

I would think that that is quite a bit being on an 87 octane tune. You might want to check out a different gas station.

 

 

Thanx for the feedback. Looking at the logs, KR is for the most part at zero but an occasional short spike sometimes as high as 6.0.

Next fillup I'll try a different Chevron and see if that makes a difference, though you would think the fuel even at different stations

would be to the same spec.

[dennismc]

Try a different gas station and fill up with 93 or 91. It could be false knock.

 

 

My plan was to get tunes for 89 and 92 (that the highest octane in my area) and compare mileage, power,drivability,etc..

[kdixer]

Short periods of KR are normal during shifts or jumping on the throttle. Basically anything that "shocks" the drivetrain can cause KR. It is the KR that lasts more than a second or two that you need to worry about. If you get KR during steady throttle under load, then you need to adjust something. If it is just a short spike it is probably nothing much to worry about.