Tuned this Raptor 2 years ago on E85 with a return style fuel system, ID1050x injectors. Truck ran great, no issues. However the idiot that built the motor built it with 11.5:1 compression pistons and a pile of other things wrong. Owner got sick of running E85 so want to drop compression. Motor was refreshed and 9:1 compression pistons swapped in. Switched back to stock returnless fuel system, ID1050x injectors remain.
Truck runs and drives great, but when coming to a stop it wants to die. No mater what I do, I can not get anything to change it at all. Including very drastic changes to desired idle air flow, and even torque/sec. It does the exact same thing with the Whipple throttle body and a stock GT500 TB i tested on it. Both TBs mirror the same action. Whats really surprising is how long it takes to recover as you can see in the attached log. I just stall it lightly in gear and you can see the idle drop to 400rpm and it takes several seconds for it to recover.
Im attaching an Idle Log as well as what I think "should" be the idle values tune. As well as a tune that I went aggressive just to try and get any changes. Short of the idle trim adjustments, the stalling characteristic did not change at all between the to tunes.
Id be looking at hardware. Wiring: either something didn't get put back together properly or got damaged in the swap. Could also be a vacuum leak, check the lines.
Reply With Quote
