Is knock while bouncing off the stationary limit normal?

Is there any way to eliminate it?

I've found that I can be bumped into low octane if I sit on the limiter long enough, and it's affecting my launch, as I'm not in the high octane map until 2nd gear.

Thanks, in advance.

 

Yes, it can be reduced / eliminated. I dont know how, mine has very minimal knock (occaisional 1's sometimes a 2 but it doesnt steadily log knock). Someone actually blew their engine with the launch control.

 

i have noticed that too... i dont wot the car thought until the lights start blinking just to avoid that...

Another thing that i want to experiment with is the richening of the map when i am on the 2-step... on my logs i see that i have -6 load when on the 2-step... which value is this on the fuel map?

if we added fuel at that point making the car to burn it wouldn't it spool the turbo more?

 

I havent ever seen the knock caused by the launch limiter last longer than the clutch being let out. If you are seeing knock after that there might be additional issues. One sure fire way (and it literally sounds better) is throw racegas in when you race whether you are running more boost or not. I experimented with this some this summer and the car will only see 1's and 2's.

 

I have had issues with knock there, and simply reduced the load areas assosicated, now no more knock.

 

I experience the same thing..I need towork this out as soon as I can get ecuflash working again..Here is a perfect example..

 

Pete, the knock was almost back to zero by the time you let out the clutch though.

Thats how it should look, the initial high knock spike doesnt matter (its gonna happen) but it is supposed to be ignored and almost immediately decay as soon as the VSS sees movement. This is what happens in 95% of the cars I have tuned and logged. If Cookie is having that knock not leave until the middle of 2nd gear I wonder if some signal is not getting through to where it should or something else is going on.

 

That's weird, my load when the stationary limter in effect is like 130-160 and my WB measures AFR at a lean 18:1.. no knock sum.

 

JB, the knock itself is gone after the launch, but by this time, my octane flag is below 100 and not until 2nd gear does it come back up

 

I'm not nearly as concerned with the performance as I am wih all of that knock just reviing my engine..I want to try to play with fuel and timing in the cells I hit while hitting the limiter and see if it has any effect or if I actually hit those cells while driving under any condition..Mabye run a bit richer and less timing and get some flames

 

Bring it up to the rev limiter slowly. Sharply stabbing the gas will cause it to knock nearly every time.

 

this is EXACTLY what i was thinking! and this way probably it will make more boost!

the only thing is that i get -6 load value when i am on the 2-step... and i dont know which cells to change...

 

Good point. I noticed that as I got my tune close to the bleeding edge if I stabbed the throttle, I would see knock. When I squeezed the throttle I did not see knock.

Sounds like the 2-step is affected by this approach also.

 

The stationary limiter hits the load cells from 120 to 160 usually.

I've played with my limiter a bit and don't usually see knock till I'm around 1 bar. I've never had the octane drop though since I've only seen as high as a 5 count.

 

I have had my limiter set as low as 3750 which yields rpms of 3600-4000 and see knock. I need to try to slow the throttle squeeze to see if that works.