Hey..

After tuning my car to a setup i like, with NO counts of knock (maybe the occasional 1-2), i noticed that doing a drag style pull with fast gear changes, the car starts knocking like crazy, reaching up to 10+ counts, killing my timing and my power. If i shift normally, i can kick it as much as i want from 1st to 6th, without any knock, i can do a WOT 3rd gear pull with no knock, but as soon as i shift fast (almost all gears) i start getting knock.

I did some research, found a couple of threads but no definitive solution yet...

Can anyone help me there?

This is really killing me, as i can feel the car gaining and losing power during drag type pulls...

 

i think the losing the power is in your head, the knock during fast shifting is normal as long as it isnt like 20+ counts.

 

It's not in my head. My car has slightly more power than my friend's STi, when we drag together, i pull off until i change gears and start knocking for a few seconds. He starts catching back until the CEL (Knocklite, thanks Tephra! ) turns off, then i start pulling away again, until the next gear change. when i don't change gears very fast, the car doesn't knock, and keeps a constant pull...

 

are you Venting you BOV? that could cause knock, and poor performance on your stock ecu when shifting, Which puts you in a very rich condition between shifts.
could be the cause..... just throwing that out there.

 

Thats correctable, shoot me a pm and i'll give ya couple pointers.

Cheers!

 

I had that exact problem actually.

What I did was found out the load cells where the knock was starting to happen like 4-6k and around 80-140 load. Then what i did was simply richen up that block of area to reflect my fuel map on the higher load. This prevented a lean spot when the pressure was releasing and stopped the knock.

 

Thanks for the help. 4ws sent me a solution that i will try tomorrow.

 

can be cause by the clutch or just the shift itself

 

well whats the solution

 

does it bogg right after you shift?

 

I had the same thing. SHift knock. It turned out to be my DP.

Also, when setting the settings for the knock light, use a short time for the light, so you can see if the knock goes away or if it sustains.

 

Yeah I'd be curious to the solution... I used to have knock up top that would cause me to shift early, and sometimes carry it into the next gear. But that was solved by pulling about 3* of timing on top in the higher rpm load cells I was in. And then simply turning the boost up another lb.

Check your timing carefully. The one thing I did notice is load spikes in logs when I would switch gears quickly and slam the pedal back down.

Which equated to momentary spurts of 315-330 load.

Unrelated but possibly related, alot of the shift change knock I experienced stopped when I got the ES bushings that kept s*** from slamming around when I'd lift and stomp on it.

But my bov is vta, and currently I have no shift change knock, or carry thru knock either.

Like always, go and do some logs and it will likley shed some light on WHY its happening.

 

my dp hits my cross member bars like a mother too.....started when i went back to a stock mani from the meagan headers......but i think they sell cross bars with a lower clearance which is what i will look into purchasing.

 

Shoot me a PM as well if ya could. Im having this issue and it needs to go away!

 

BUMP someone has to have experienced this and has a solution...