Please help if you can. I have been tuning for KR for days and can't seem to stamp it out. I am attaching HPT tune, config, and typical scan.

Basically 2500-3200 rpm, Cruise, light acceleration, .28 thru 1.0 g/cyl airflow. PE or not. 2-5* hits of KR. At no time since installing the SC have I heard audible knock.

Things I have tried.
93 Octane always. Presently a bottle of Lucas Octane boost. - No Change
Timing in these spots dropped by 10* - No Change
Into PE sooner with AFR from 12.5 to 11.5 - Still KR but not as bad at 11.5.
Knock Sensor Level>vs. RPM vs. Cyl> 2500-3500 rpm all cylinders increase by 1 and no change.
I've logged tranny shifts and TCC locks. Have identified 1-2 shift to very small hits of KR most are not associated to shifts and TCC locks that I once thought.

I am going get under the truck with a rubber mallet and try and find something banging with the exhaust but don't think anything hits.

TIA for any input.
Roger

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Could be a damaged Cat.

 

I think it almost has to be mechanical/false but have to be sure. I don't think its the cats unless they have gone south recently. They aren't that old and I had them off with a tranny install just a few months back.

Would a rubber mallet to them be enough to sound them off? Look for something loose in them? or would it be a flow issue?

 

Heres my take on things...take them FWIW because I have yet to do any forced induction 2 bar applications

I personally wouldve done the pe tables a bit differently

• the map enable makes entering PE mode VERY abrupt at points like at frame 811
• I find it very ODD that you command a richer afr at 110kpa-130kpa then 130+kpa I would've set it up something like this

this would progressively get you where you'd want to be rather then this drastic change from stoich right to 11.5:1 once you hit pe even at like 2200 rpms.



also you can see that KR drags out for a while, you might want to consider upping your KR decay table a bit so it doesnt drag out so much.

Anywayz thats my take on things.

 

I'll try a smoother transition into PE. Thanks for the tip.

As far as the 11.5 commanded to 110KPA to 130KPA, Then 11.8 on out. Not proved out yet but I've read and been told richer to max torque (3800 rpm) then lean out from there. This area is still to be tuned as it probably won't do what I want. Not spending a lot of time with it yet, it will be all different once the meth is back on.

I've already doubled the KR Decay rate. You're right I will probably double it again once I am confident it isn't gonna tear things up.

Thanks for the input.

 

yeah the major thing I'd be concerned with is that 80kpa marker. Just seems a bit high for your application.

Yeah I noticed you just kinda roughed in your VE in the boost regions and probably hadnt touched it yet, but if your looking to go richer at peak tq thats what the multiplyer by rpm is there for.

The boost table just adds extra resolution for you...as far as I know the computer will take the richer of the two, so setting your mult vs. rpm to go to 11.5:1 at peak tq & leaning it out to 11.8:1 at peak hp would be the way to go with that.

 

i haven't looked through the scan yet Ky but on the pe thing. I did alot of experimenting with pe/be tables, ALOT and I am certain foff is correct in the fact that a smoother transition is gonna help make air/fuel calcs happier. I am sure you know, the pcm will pick the richer of the 2 (pe or be). This is very important to remember with your attempt to make a smooth PE to BE transfer. I like a real lean pe. This way of tuning pe/be I believe has made it easier on me to tune out kr on the low rpm, high kpa areas. pcm will not hiccup, high kpa gets the richer setup. It looks great on the wideband too, nice smooth roll to final destination instead of WHAM 11.6.

my kr decay is like .75 LOL, how's that for a difference?

on the max tq w/rich thing. My understanding on TQ is spark and fuel spike at the TQ curve. This harder to accomplish with not just FI, but a RADIX'ed FI at that. But just dip the spark a little going into the TQ curve and raise it back coming out of it. Raising spark for me has always caused it to natuarlly get a little leaner.

 

LOL...look how long it took me to post that. LOL

this is why i love 2bar. Mine is 85kpa.

 

Forgot to add to things I'd tried. Another being transition to PE at 50KPA, 12.5 AFR. to about 2500rpm then down to 11.8. It didn't affect KR at all.

 

I looked at your tune and scan and compared to mine (2005 Sierra 5.3 RADIX 3.0 pulley),

what I found is that in the area's that you have 1 to 2.5 deg of KR my timing tables are 2deg's less
Example:
at 2800rpm @ .56 g/cyl you have 2.2 KR at a comanded spark adv of 24.90.

my truck at the same place has only 21.30 of spark adv.

Have you tried using the VCM tools in the scanner to subtract timming to see
if it will go away?