Can't pin point when this started but I've noticed what I'll call a surge in that when using any of my DSP5 tunes, it seems to idle a 100rpm higher for a second or two right before I come to a stop or if i let off of the brake and idle forward or backward. The result is the truck then kinda jerks as if I'm hitting the gas pedal on and off real quick. Weird thing, it doesn't do it if i'm in the base tune of the DSP5 or put back the stock tune. Any ideas, I've combed through my tunes I have loaded on the DSP5 and I can find anything that would cause this problem, especially at idle as my tunes don't have fuel or timing come until about 1k?

Did you add PW anywhere in the 1-10mm3 range? I had the same thing with one of my tunes. Turned out I highlighted mm3 rows 7-100mm3 when I wanted to select 10-100mm3. When I got to 2mph the engine comes out of "Idle mode" and I felt it kick like you described. I returned the PW <10mm3 to stock and problem solved.

I'm still learning when it comes to EFI - help me out here, what is PW? BTW, what you described is what I'm seem to be experiencing - I've narrowed it down to when it comes in and out of idle mode, just haven't been able to correlate it to any of the DSP5 tunes since idle mode or its parameters aren't an option in any of the DSP5 tunes.

ok, think you mean PW = pulse width - so i double-checked that its set to 0 all the way down, so that doesn't appear to be the culprit but it definitely seems to be related to stop and run idle...

do a log when it does this and study it, look at your fuel pressure and PW tables

LarryJewell - thats my next step, log it and see if i could figure out what its doing... BTW - I see you're from San Angelo - I was born and raised there, then moved to DFW area after graduating from HS in '86. I'll send you a PM see if we know each other...

LarryJewell - thats my next step, log it and see if i could figure out what its doing... BTW - I see you're from San Angelo - I was born and raised there, then moved to DFW area after graduating from HS in '86. I'll send you a PM see if we know each other...

I graduated HS in 84' "Central", so we probably crossed paths at sometime or another.

Anyway, I cleared my surge up with very small changes to 2 tables :D

Yep, thought about that as well regarding the two tables - was just trying to figure out why suddenly it would have started.

Yeah, I'm sure our path's crossed, I went to Central as well. Small world I guess.

Maybe the tunes are asking a little much of the Fpr. Id get it checked just in case.

The idle tuning is kind of a seperate deal and I'd bet that that surge your talking about occurs at exactly the speed where the ecm switches to the "idle tuning". I dunno what that speed is, I think its set at 3km/h or something.

So to fix it you'd want to compare the parameters... timing, fuel etc.... while in normal tuning and in the idle tuning and make them the same.

Thats my best guess anyways.

Checking in....

So i've tried and then some on the things the folks here have suggested with no improvement or even change to the surge. What is interesting is that on my DSP5, if I go to the base tune or position "0" on the switch, the surge goes away. If i try any of the other switch positions, the surge comes back immediately. Could this be a switch problem?

I'm taking what I have in my base tune or position "0"(btw, its stock) and trying in a few of the switch positions to see what happens - process of elimination here....

For anyone interested, figured out my surging problem...

In each of the DSP tunes, I misunderstood &quot;Injection Timing after Pilot (c,d). I was copying from the stock tune table c of the timing after pilot into the DSP - injection timing after pilot (c,d). Once I reread the definition of the dsp calibration for &quot;injection timing after pilot(c,d) in that C is for LB7 and D is for LLY, i copied over the correct table as it resolved the surging.