I have a lot more things to try with my tuning so I'm not out of answers yet. I just wanted to know what you all have done to handle this.

I seem to pick up a little knock from the vacuum to boost transition point. When monitoring, I see my timing retard mode engage and voltage on the knock sensors spike when I roll over the 0 vacuum point into boost. It's like 1psi of boost registers before fuel can get from 14.7 down to 11's. That might not be the culprit, but I always pick up some knock at the instant boost builds.

You guys ever monitored things that closely to notice it on your engines? I have a handscanner which is the only way I see it. I hear nothing. Its probably just over sensitive knock sensors but I don't want to put in resistors to fool the pcm everything is fine just in case something ISN'T fine some day.

 

I get the same exact thing when I'm cruising down the highway at low rpm (1900-2400). go from 0 vac to 1 lbs of boost and bam, big KR. I've tried lowering timing and its hasn't helped much. I get some pretty big KR from it some times too, like 6-7 degrees, but no autiable knock. I know this doesnt help you any, but I have it too if it make you feel any better. I'm still working on it though.

 

Sounds like an issue i was having when getting tuned. They called Jessie (from EFILive) and he said it was "Boost Knock". from the sudden burst of air. It registered pretty high....high enough you should have heard it, but we didnt....just sounded nice and smooth. He said it was a false reading for the most part. We fiddled with a few other things and brought it down a little, but Jessie said he sees it all the time and its nothing to be concerned with. It is one of the things we are going to look into further when i go back in. It was much more obvious on the dyno than is was when we took it out on the road. The KR read MUCH lower on the street at the same point than it did on the dyno. Not sure if its the same thing your dealing with or not, just thought i would throw it out there.

 

Our GM engines have a pe enable rate, not sure what the dodges have but I would enable open loop fueling just before you get to the point where you expect to start seeing boost, . I think your looking in the right direction with the tip in KR being from lack of fuel.

Something else that might help is a vacuum referenced fuel pressure regulator.

glad to see your over here from HPT

 

I think everything that is mentioned here is my same issue. I pull 4 degree's timing out starting at 75% throttle position. Then pull 6 degree's out in high boost which is 8psi and I am initially at 25 degrees WOT timing. I end up with 19. However, it takes about 75% of my run to overcome the initial knock retard mode.

I've even tried spraying in meth at about 75% throttle and around 5 vaccum to start a fuel source by the time boost comes on. Doing that and taking out 4 degree's timing at 75% throttle still doesn't stop the knock retard mode from popping like 5 degree's on me.

Dodge PCM's suck for tunability. I do all this with the smt6. I can't go into open loop sooner unless someone knows how to do that via the smt6 and a Dodge.

 

I have the same timing issues as everyone has mentioned also, around 2100 to 2500rpm. Especially in overdrive, it is driving me nuts. I would like to know how to get rid of it.................

 

My sensors don't detect knock at part throttle boost conditions. They only detect it when I floor it and get that vacuum to boost transition. For part throttle conditions I just retard timing and let the pcm maintain 14.7 a/f. I believe my map voltages are correct at part throttle boost conditions that allow the pcm to work with the boost.

I will continue to play with timing and map voltages for that WOT transition. I wish I could induce open loop a little earlier to bring a/f down sooner.

 

Hemifever does SRT10KLLR see the same thing? I know the early model GM PCM's would pick up a false knock but Linda is running a 2003. If SRT10KLLR is not having the same tip in, maybe it's yet another $%^#$* computer glitch the 2003 Hemi folks need to work on.
I imagine the performance feels sluggish on the transition point. One interesting thing is not getting the same KR at part throttle. I wonder if something else in the system is causing it. Does changing your MAP table move the KR around? It may not remove it but make it happen somewhere else in the vac/boost range....

 

The "boost knock" refered to above is "burst knock" and is somethign the PCM does when it expects knock to occur but hasn't seen it yet.

Kbracing -- your issue may be tip in KR -- a result of throttle transients and can be tuned out via SD VE tuning. If you are getting a big downshift say 4-2, it might also be from the TCC settings (these trucks are notorious for it) -- start by adding 5-7mph to all your TCC apply settings if that's the case. It can be tuned out (everyone I've talked to has had the same issue).

For the dodge guys, if everyone is seeing the same weird behavior, it might be something dodge put in to the OS not considering you guys would slap turbos on there... some kind of engine protection mode or the like. It could also be trouble with the transients or a glitch in fueling.

 

Yea, sorry about that.....brain fart on my part.