CL only, part throttle stumble c6zr1

[bjlindell]

Ive been battling this issue for years.

ive always blamed myself but now im thinking it is possibly o2 sensors? also assumed it was a corrupt file, so i rebuilt the file and reloaded it. Ive also reflashed the controller with factory cal from a MDI module and still same issues occuring.

This 1500rpm and 2400rpm is very consistent at light throttle.
Ive tuned the car in VVE and MAF in OL and all is as great as it can get and no issues what so ever in OL. But once i enable CL, the stumbles come back in those areas at 75kpa or less.
Car is an awesome driver in any other condition.

Below i have some snap shots of the situation occuring and hoping someone else had some insight on this. Tune and log attached as well.CL stumble zr1.hplbandvzr1 factory HC BEST BLEND MAFVE.hpt
It feels like a major misfire and feels like it. it drops out on power at those moments. but again when i command it in OL with the controller, it drives perfect through those areas. Put it back again and it stumbles every time. ive tried to make PE come in earlier to eradicate it and it has helped some so far, but it is getting close to running PE while cruising on Highway.

Ive messed with all o2 tuning settings in every which way and it has not helped the situation at all.

1500rpm stumble and around 2400rpm.PNG
1500rpm stumble CL.PNG
2400rpm stumble CL.PNG

[bjlindell]

forgot to mention this is a Head/Cam Full bolt on car.

No codes pop up indicating O2 performance or anything O2 related at all, just misfire codes when this stumble occurs.
of course plugs and wires are good. but would be odd if it was plugs/wires since it is consistent at 1500 and 2400 rpm with plug and wire changes as well

[bjlindell]

Just wanting to add another note, of course it looks like that area goes dead lean. every time i give it what it wants in that area for fuel, this stumble still occurs and it goes dead lean and makes the vve map and maf spike in that area (pic below)
vve map view.PNG

[Lakegoat]

Did you think that maybe the maf and ve table are the problem? Smooth out those manually and see if it goes away.

[bjlindell]

I run Methanol injection, that's why the Maf looks that way. But for the VE, ive been shaping it that way since thats what it keeps wanting, mostly in OL and small adjustments for when its in CL.

But when in OL it drives great and A/F stays a small error of commanded (minus the area where the peak is in the VE, it goes rich for trying to make up for the stumble in CL) so that kind of points me in the direction it may not be table smooth?

[sgod1100]

Ive been battling this issue for years.

ive always blamed myself but now im thinking it is possibly o2 sensors? also assumed it was a corrupt file, so i rebuilt the file and reloaded it. Ive also reflashed the controller with factory cal from a MDI module and still same issues occuring.

This 1500rpm and 2400rpm is very consistent at light throttle.
Ive tuned the car in VVE and MAF in OL and all is as great as it can get and no issues what so ever in OL. But once i enable CL, the stumbles come back in those areas at 75kpa or less.
Car is an awesome driver in any other condition.

Below i have some snap shots of the situation occuring and hoping someone else had some insight on this. Tune and log attached as well.CL stumble zr1.hplbandvzr1 factory HC BEST BLEND MAFVE.hpt
It feels like a major misfire and feels like it. it drops out on power at those moments. but again when i command it in OL with the controller, it drives perfect through those areas. Put it back again and it stumbles every time. ive tried to make PE come in earlier to eradicate it and it has helped some so far, but it is getting close to running PE while cruising on Highway.

Ive messed with all o2 tuning settings in every which way and it has not helped the situation at all.

1500rpm stumble and around 2400rpm.PNG
1500rpm stumble CL.PNG
2400rpm stumble CL.PNG

i've been battling that on my ctsv for a few years as well....lol. I've been told that it's "reversion" in the intake causing the maf to read lean. SMOKESHOW has opened my eyes to it and it does make sense. Tuning it out is a different story....

[bjlindell]

i've been battling that on my ctsv for a few years as well....lol. I've been told that it's "reversion" in the intake causing the maf to read lean. SMOKESHOW has opened my eyes to it and it does make sense. Tuning it out is a different story....

I have the cal reference the dynamic airflow up to 2700rpm and MAF only from that rpm and up to redline.
I ended up getting something that helped reduce it to almost being gone completely so far.
I put it back to the factory o2 settings and just reduced "Closed loop prop limit" ECM 12486.
it had values of 2 across the board. I set it at 1 and all seems to be better. Still a tiny bit noticeable but much much better so far. I may try and set it to .9 or .8 and see what that does. but happy with the results

[sgod1100]

I have the cal reference the dynamic airflow up to 2700rpm and MAF only from that rpm and up to redline.
I ended up getting something that helped reduce it to almost being gone completely so far.
I put it back to the factory o2 settings and just reduced "Closed loop prop limit" ECM 12486.
it had values of 2 across the board. I set it at 1 and all seems to be better. Still a tiny bit noticeable but much much better so far. I may try and set it to .9 or .8 and see what that does. but happy with the results

Yeah, I've tried testing all of those 02 settings and while some felt better than others I can still see it on my WB and feel it too. I've pretty much giving up on trying to completely fix the problem...because...well...I don't know what else to do...lol. Looking at your logs that's exactly what mine does around 2600 rpm..you can see the o2s aren't switching at that point too.

[J-CUE]

Is desoot mode disabled?
I know its a silly question, but still worth asking. lol