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Old Mar 21, 2009, 03:52 PM
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Question Lift Off Knock

I'm getting some fairly high knock counts (10+) whenever I lift off the throttle (both partial & WOT). It's worst when at WOT, but not at red line. I have no knock anywhere else. Anybody know a fix for this?

  • Evo 8
  • WORKS 269 cams
  • FP White Rabbit 9 Turbo
  • JDM MAP / ECUFlash boost control

thanks!
Attached Thumbnails Lift Off Knock-lift_off_knock.jpg  
Old Mar 21, 2009, 04:05 PM
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Originally Posted by voidhawk
I'm getting some fairly high knock counts (10+) whenever I lift off the throttle (both partial & WOT). It's worst when at WOT, but not at red line. I have no knock anywhere else. Anybody know a fix for this?

  • Evo 8
  • WORKS 269 cams
  • FP White Rabbit 9 Turbo
  • JDM MAP / ECUFlash boost control

thanks!
Have a log with load? Be interesting to see the difference in load values before and after you let off.
Old Mar 21, 2009, 06:25 PM
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Originally Posted by codgi
Have a log with load? Be interesting to see the difference in load values before and after you let off.
I didn't log load on that run, so I went out and tried to do it again, but now of course the knock is gone ... I'll have to try some other time again.
Attached Thumbnails Lift Off Knock-log_01.jpg   Lift Off Knock-log_02.jpg  
Old Mar 21, 2009, 06:47 PM
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sounds alot like an issue i was experiencing. I would lift off the thottle and my knock count would go crazy.
Looked alot like this in my logs:

12
10
8
7
6
4
3
1
0
0
0

Turned out that the HKS SSQ BV was soo loud.... it would trip my knock sensor. Dont know if this is your issue...
Old Mar 21, 2009, 07:27 PM
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Originally Posted by WickedWhtMR
sounds alot like an issue i was experiencing. I would lift off the thottle and my knock count would go crazy.
Looked alot like this in my logs:

12
10
8
7
6
4
3
1
0
0
0

Turned out that the HKS SSQ BV was soo loud.... it would trip my knock sensor. Dont know if this is your issue...
Interesting thought ... my BOV is adjustable, I'll try to set it to full recirc and see if that does anything ...
Old Mar 22, 2009, 12:11 AM
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Originally Posted by voidhawk
Interesting thought ... my BOV is adjustable, I'll try to set it to full recirc and see if that does anything ...
Still running the GFB? I did think of what WickedWhtMR said too and might not be a bad palce to start. Also anything loose maybe? Downpipe? O2 housing? When you let off on an Evo and have a passenger watch their head and you will know what my angle is .
Old Mar 22, 2009, 12:15 AM
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Originally Posted by WickedWhtMR
sounds alot like an issue i was experiencing. I would lift off the thottle and my knock count would go crazy.
Looked alot like this in my logs:

12
10
8
7
6
4
3
1
0
0
0

Turned out that the HKS SSQ BV was soo loud.... it would trip my knock sensor. Dont know if this is your issue...
Lol Yea I remember that... Crazy!
Old Mar 22, 2009, 07:13 AM
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Lift off knock is fairly common. Some times you can fix it some times you can not. Make sure none of the motor mounts are torn and that you have at least a front motor mount (roll damper). Look into upgrading the rear as well (I assume the evo has a rear, my car is mostly stock, never looked). The side mounts really don't need upgraded but make sure they are not torn. I've also seen some alignment issues with some of the billet front motor mounts on the market that causes the motor mount to hit the mounting plate or other hard stuff on the car. In some cases (and I'm not picking on you) the driver of the car just needs to learn to shift better. Harsh abrupt shifts will tear the gears up and cause issues like this.

Then of course you have 1000 other things to check. Clutch noise, downpipe, loose parts, ic pipes.......
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