i need some help here, i am seeing lots of KR, right now i am runing only 5psi of boost, the coolant temp is around 175deg, the o2's are .92 to .90 the pcm is only asking for 4-10deg of timing and i am geting 5-8deg of KR.

first is it really false? i made a few runs and loged the KR then i thru in a 30% mix of xylene with my 92 gas(about 100octane now) then made a few more atap runs and the KR and timing didn't change. sounds false to me but with the blower i don't want to just disable it.

what can cause false KR? how does the knock out box work? can it reduce false knock and still pick up real knock?

 

Man that sure sounds like false knock to me.

I was running 4-4.5psi of boost, 18-21 degrees of timing, .89-.93 O2's, with coolant temps hovering at ~200, in my higher compression f-body with no KR on 93 octane.

Maybe you have a bad sensor or its picking up some resonance from something.

Can't you use LS1edit to mess with the Knock sensors sensitivity?

I was just thinking that your giving up probably 30-50hp in timing alone. I think you should be able to run at least 18-20 degrees(maybe more).

I would try some real unleaded race gas 100+ octane and if you still see knock then maybe try replacing the sensors, if you don't want to just desensitize them, to see if that helps.

Tuning looks to be a big reason why your truck is down on power. I know what the difference in 5 degrees of timing felt like on my car so I can imagine what 15+ degrees would do. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

John

 

i was hoping that excessive back presure was causing my KR but that doesn't apear to be the case. i would like to adjust with ls1edit but i can't find a thread that tells me how. my truck is a dog and i am becoming discouraged. it revs slow and has little power. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

i believe i can use ls1edit to slow how quickly the KR comes on and to quicken the time it fades away but if it is a constant false signal i don't think it will make much diference. i need a way to make it ignor a signal under a certain level.

 

i know you can desensitize knock with ls1edit, there's a section called knock retard under engine management. check that out

later

 

Well shoot. I had the same issues you did. I could do very little to get rid of the KR.

One thing- Ice down the SC compressor. I put a bag of ice on it and let it get nice and cold. Also ice down the metal intake "elbow" as that gets pretty hot too. Warm up the truck to just about operating temps. Then take it for a couple of quick hard WOT pulls. Compare the results with the compressor hot. I found that when I iced it down, I had less KR even though it didn't register in my IAT. I saw less KR, but didnt notice much more power.

I think that the 99 PCM is crap. I think that LS1 edit only gives you very few parts of the whole PCM puzzle, and our 1999 PCM has some issues from a performance standpoint. From what I can tell, the newer years have much better results with the whipple. 01tahoetwinscrew ran sub 14s in a 01 tahoe 4x4 that is heavier that either of our trucks. With the whipple and all my other mods, I doubt I'd be very far into the 14s. I have been very tempted to see if I could get an 01+ flash thrown over my PCM and see the results.

 

Would it be possible to get an 02 flash on my 00? Would this make my truck as fast as the 02 trucks that run 14s bone stock?

 

i can't remember where i got this from.

The easiest way to desensitize it
in the computer is to decrease the spark retard attack table - you can also increase the spark decay table. Doing this will decrease the rate spark is taken out per knock event, and increase the rate you achieve full timing (respectively).

good luck,