So been dealing with this for a very long time now, with help from the top dogs of the tuning world. Running out of ideas here, not aware of any mechanical issues, at least that could be found. The main issue is when coming to a stop in gear, or when in reverse and the lightest bit of throttle applied, it gets into a HUGE surge going from 200-1300rpms in a continuous cycle. Attached is the original tune after WOT and in gear idle was dialed in. This log shows the most obvious surging, but this log was with the PT and minimum timing tables raised up a bit, but made zero difference. Honestly after 22 revisions, we have only managed to make it worse than the tune attached. Here is what was tried with zero impact to the surging:
-Torque modifiers cut in half, then completely zero'd out as a test, only made the issue worse both ways
-modifications made to injector flow
-Cut VE by 10-15% (even though trims were adding fuel), zero difference
-I have made tons of attempts at modifying the spark tables, raising the timing def helped the cruising surge from 1200-1800 rpms (fluctuates 100rpms) but made no real change to the big surging I get when coming to a stop
I have def narrowed the problem to something relating to the throttle correlation, I THINK. Here is why, if sitting in park, I apply say 5% throttle and hold the pedal perfectly still, the RPMs rise to 1200-1300 rpms then IMMEDIATELY get pulled down and brought to near stall, then jump back up to 1200 and will continue to do this cycle, even though the pedal is EXACTLY still.
Other observations of note, the tune USED to surge all the time, in park/neutral, basically at anytime at idle, so I am convinced since the in park idle has been 95% fixed this still remains a tune issue. I am seeing some pretty big value differences of SENSED MAP and READ MAP while datalogging with DS. Don't think that's normal. If you look carefully in the log attached, there are times where the commanded torque can go really negative or just flat lines at 32ft/lbs for the entire surge cycle. In the log the first surge cycle was after putting it in reverse, and lightly touching the throttle while holding the brake, but then letting off the throttle and letting it just sit there.
2006 300C NGC CAN REV15A PT Timing 2.hpl
2006 Chrysler 300C NGC3 CAN No TCM Rev15.hpt
Full mod list:
426ci low comp 6.1L based stroker (9:1)
HHP stage 2 heads, cnc + hand ported
2.9 whipple, 2.75" blower pulley, 17% OD crank pulley, seeing 15-16psi
Custom Cam: 239/251 duration, 600 lift, 118+2 ICL
SHR trans, Getrag 3.06 rear, stock height wheel/tire combo
3 BAR MAP sensor
87mm Modern Muscle stock ported Throttle body (have switch to stock to see if this was the issue, no change to surging)