last time i went out to check the tune on my car i decided to accelerated during idle i rev'd up to 7000rpms applying and lifting the throttle and to my surprise i saw knocksums go as high as 8 why would this happen is this normal?
thanks

 

thats why the car in idle dont should be on thats rpm hehe just for racing

and what says the log from the pulls?

 

my personal opinion is knocksums should only be looked at when under load conditions..

other times they arn't important..

guys?

 

i agree with tephra on the most part, this knock can be as simple as the sudden combustion rate change or the sudden application of boost. also the sudden shift in load can make this occur. What was your timing in those areas and did the knock spike and feather down? watch timming and see what its at. If your not knocking during a pull, then more than likely your OK. Got to remember that knock filters work on a freq. and really the freq. isn't that hard to re-create, with that being said anything in your engine bay that chimes at just the right freq. can be picked up by the knock filter.

 

How do you "accelerating during idle" ??

 

I think he means revving while stopped.

I would agree that if your knock is in check during a pull, it shouldn't matter if you get knock while revving. Unless, of course, you knock while using the launch control and your octane value drops .. that would possibly slow you down on a drag run.

 

sory i meant revving up the engine during idle i didnt see my timing but when its at idle my timing fluctuates from 5* to 8* is this normal also?
and yes i dont have knock during 3erd gear or 4th gear pulls

 

just for clarity: idle = condition when no throttle is applied to the vehicle, whether moving or stationary (usually stationary)... therefore you are confusing people by saying "revving during idle" sorta contradictory.

Your engine sounds much different under a free-rev than under load. Remember that and remember that the ecu has logic to determine when knock frequencies are not important. (It likely does not filter out noise while revving just to be on the conservative side)

 

what about timing during idle being stationary?

 

I think your eyes need to be wide shut for that.

 

if you hit tthe limiter that causes knock some times!

by hittting the rev limiter on my STi my knock link would light up like a christmas tree!

 

what about timing during idle without touching the accelerator at all?
in my car i see timing go from 5*-8* is this ok?

 

Yes, that is OK. Your load fluctuates even during idle, and thus causes your timing to bounce around a little too. Now, if your timing was bouncing around from say 5* to 30*, yes, you have big problems... If I remember correctly, your car will idle between 750-1000rpm's and 30-40 load values, and if memory serves me correctly, the stock map in those two load cells (timing numbers) will cause the car to jump around a little. It's OK, no worries, my car does it too.

 

thanks

 

Don't forget that bad gas can cause knock also.