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cruising on freeway knock


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Started seeing a lot of fklc on my accessport so I logged it. Was just cruising on the freeway, light throttle under vacuum. What is weird is as soon as I give it some throttle it would immediatley stop showing knock and when I would let off it would show knock again.

 

Here is the log. Please let me know if anyone can make sense of whats going on?

 

https://docs.google.com/spreadsheets/d/1QvLDI6Zc7b84QZrIbFBNDM4r2ifS_ZNm82n1FAF74y0/edit?usp=sharing

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That's a lot of FLKC. You see it go away when you apply throttle b/c throttle application increases the engine load and takes you out of the rpm/load region where the learned corrections are stored/applied.

 

Might be something rattling under the hood or a loose exh heat shield or something like that.

 

Do a quick log at idle, that records AF Learning #1A, B, C, D. Curious what your fuel trims look like.

 

[Edit: If you look at row 961 in your log, your DAM drops from 1 to 0.5, at 3038 RPM and 1.7 g/rev load. 1.7 g/rev is not a trivial engine load, but since it happened just as you were lifting off the throttle, it might be false knock from a rattle. Check underhood/under-chassis to see if anything obvious might be falsely tripping the knock sensor. You may not see more FLKC for a little while since the DAM drop also results in the ECU clearing your FLKC table.]

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I poked around under the hood today. I looked where the knock sensor is located and found a bunch of debris on and around it (leaves and twigs) . Also the splash guards were flapping around in the wheel wells so I got some new rivets for them. I checked out all the heat shields and they were all tight.
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So after a week and 330 miles of no problems, it started doing it again. Cruising at 70mph 2700-2900 rpms and was getting high feedback and fine knock. It seems like when I reset the ecu I'll be good for a week and then it comes back. Any ideas???
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I have the same thing with my car. I can't for the life of me figure out what is causing it.

I think it must be some internal mechanical engine noise that freaks out the knock sensor. What's your mileage at?

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I had my turbo heatshield off today and discovered that the bottom part wasn't connected properly. Put it back on right and had no knock at all for 22 miles on the freeway. Then while changing lanes on surface streets it jumped up to -5.6 fbkc and then zeroed out and stayed at zero the rest of the way home.
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