I'm at my wit's end with this thing!! At this point I've tried absolutely everything possible with idle control to alleviate this surge but NOTHING, and I mean NOTHING I've done has resolved it. I've played with the PID controller up and down to absolute exhaustion, I've completely disabled and zeroed out all the airflow adaptives that I think have anything to do with idle control.... nothing helps. In most starting situations the truck idles down and then immediately your can audibly hear the throttle blade going crazy and see it in the datalog as well. Sometimes it will begin it's relentless surge after a quick neutral rev but what upsets it bad and gets it surging every single time is a held rev in neutral or park to any rpm. If you just hold it for a couple of seconds and release the throttle the RPM drop quickly to about 500 rpm, the truck almost dies, and then it goes bananas. Just surging up and down for sometimes a minute straight unless you give it some throttle to settle it. Myself and a couple of other local guys have tweaked this same truck with no luck. We both thought we were dealing with a bad throttle body/IAC/TPS sensor, but that's just not the case. We've swapped 2 new ones on at this point both AC Delco and Dorman and the issue persists.
I did not tune this truck initially but at this point the only thing left in my mind is MAYBE something with the injector data???? In checking the part number the injectors appear to be the Siemens Deka 80s with the red bottom. Having never tuned these personally after a quick search there appears to be tons of conflicting info about accurate data. Anyway, setup is as follows... I sure hope someone can help with this!
-05 Silverado, stock 5.3, very mild unknown boost cam
-Return style fuel system, On3 regular reads 78-80 psi (holy moly), Deka 80lb injectors (part number A2C32624700/K052A01527), tuned @ 15 psi on E85
-Twin 68mm turbo kit
-Stock intake manifold/throttle body
-MAP sensor# 12615136 (I double checked this data and found a 8 KPA offset instead of the 10.33 that this truck was tuned with... any input??
The datalog attached is of a rather smoother idle honesty. This log didn't capture the crazy surge but there's nothing that stands out in the data when it's doing it anyway.