Creederado did a good write up on this in the performance section.
The '99 pcm had a much harder time holding timing and showed alot more KR with the same setup as opposed to the 01 and 02 PCM's. The base tune is also different from what I hear. If I recall correctly this also included some perameters that couldnt be accessed via EDIT.

 

Ok, so for best performance or big complex setups it is wiser to swap out to a new PCM and not try to mess with the 99'?

I'm just trying to get some info so Chris can get his truck running optimum. Rick thinks that his truck has a bunch more in it but tuning it was a bitch due to the KR and such.

 

the only way ive seen people make big power (parish) and others on a 99 pcm was putting resistors on the knock sensors i htink it would be more wise to just switch the pcm for an 01+

 

Hey Chris is that the .96 A/R housing on that 67?

Oh -- check for pin hole exhaust leaks and check all your vacuum lines. I had a similar boost issue from a blown out ( ) vacuum line and a bunch of shoddy welds.

 

My remote setup on my truck would build boost like a cent. blower, and it puzzled me for a long while. I finally did a boost leak test, and found a massive boost leak. Now I go from a couple psi to full almost instantly. Check your pressure tubing, and vaccum lines for leaks.

 

The 99 Pcm's had problems with timing and such from the stock tune. They also were notorious for having alot of false knock. I believe that if I upgraded to say an 01 or 02 PCM, while tuning, you could possibly run more timing and not see the KR. Every setup is going to react differntly, you can actually know until you try it. I'm getting no KR now, so i'm not worried.

I thought about having a possible leak in the pressure pipes from the turbo, but I dont think I do. The turbo and the housing are on the bigger side for a 5.3. So i think if i can cam it/add some heads and higher octane, i'll see some big improvements, being able to run more psi and more timing.

I'll go ahead and have the pipes and lines pressure tested for the heck of it.

 

Part of the reason you are seeing no KR is because Rick dropped the timing again. He said that at timing like I have on my truck you would KR like a **** but you made better power. To be safe he lowered the timing back down though so the motor stays together just in case some of it wasn't false. Hehehe

If you get to where you wanna try the smaller housing let me know and we can work something out on my .81 A/R. I'm gonna have to use the .96 on my bigger motor for sure. You can keep your .96 though since I already have both