2010 Challenger R/T - Comp 274 Idle Driving/Rev Hang

[Moparmaniaccuda]

2010 Challenger R/T 6-speed
Comp 274 cam, JBA long tubes, LMI true CAI

Had the car tuned by a reputable tuner via DiabloSport 2 years ago. Transferred over to HPTuners as I've had this one issue that I was tired of waiting for the tuner to try and resolve (went through 6 revisions with him with no real improvement). Car runs great at WOT and idles great, the only issue I have is that there seems to be some kind of "wall" at 1900 rpms where the car wants to idle drive and rev hang between 1900 and about 2200, but outside of this range the RPMS fall quickly and smoothly. I can watch in the datalog below that as the RPMs are falling around 2k rpms, the spark advance is around 40+ degrees (seems like all of the advance in the PT throttle table at that aircharge), yet when the RPM falls below 1900 rpm the advance falls to single digits which is where I would expect it to be.

Not sure if this is all making sense, but its been frustrating to say the least. I've tried adding/subtracting from both the TB model and small/large desired airflow tables with no real change to this specific issue. I've changed airflow to torque values (cutting them by 15%) with again no real change to this issue.

Anything else I can try before I just set my PT and MBT spark tables to use 5-10 degrees of timing in this area? This almost seems like some kind of glitch in the computer, or more likely me just not understanding what's going on (my setup is far from unique). Tune and log posted. Thanks in advance.

[AVMPerformance]

Go into Airflow/Electronic Throttle/ETC Throttle Body Airflow

lessen the airflow where there RPM hangs In relation to the throttle voltage. Meaning if you let off and it hangs around 1500rpm, and .20v for throttle position, lower airflow slightly at that point, one or two cells above/below may need adjusted with it to interpolate properly. This is how my tuner helped me get mine to stop rev hanging. hopefully it helps you.

Screenshot (110).png

[tbrtuning]

Raise the airflow to have throttle be closed more in that area. If you reduce it you will have more throttle angle as a result

[AVMPerformance]

Also, just noticed this. I would adjust fueling for that area, you need a new table setup as your tuned off NN (neural network). You need to make adjustments in the VE bank 1/2 Tables. I see you had the table setup for fuel mass correction, I had major issues and apparently shouldn't tune through that.

[AVMPerformance]

Raise the airflow to have throttle be closed more in that area. If you reduce it you will have more throttle angle as a result

Ahh, so more airflow in that section means it will be closed more? how does that work, still learning.

[tbrtuning]

Yeah. What you're doing in that table is telling it how much air is moving at a certain point and the PCM is targeting a torque or airflow value (the two are closely related so more airflow more torque). If you do not change the amount of power or airflow the PCM is targeting the trick is to tell it that it is moving more air to make it think it reaches its target with less throttle angle.

Reducing throttle body airflow a bit can liven up a basic bolt on car too in a similar way to modifying driver demand. It thinks it's not flowing as much air so it will cause it to open the throttle more to hit targets

[AVMPerformance]

Yeah. What you're doing in that table is telling it how much air is moving at a certain point and the PCM is targeting a torque or airflow value (the two are closely related so more airflow more torque). If you do not change the amount of power or airflow the PCM is targeting the trick is to tell it that it is moving more air to make it think it reaches its target with less throttle angle.

Reducing throttle body airflow a bit can liven up a basic bolt on car too in a similar way to modifying driver demand. It thinks it's not flowing as much air so it will cause it to open the throttle more to hit targets

Makes Sense! awesome explanation too, might help explain why my drop to idle tries to die sometimes...hmmm...

[tbrtuning]

Yeah. Lower airflow a bit to let it catch a little above your commanded idle and see how it does. That table is often misunderstood I believe. Watch AFR when it does too too though. Often see a rich spot low in PRatio of VE tables cause that or at least make it worse.

[Moparmaniaccuda]

Thanks for all the replies. That is the way I understand the TB airflow model to work as well (If you look at my tune, the 0v-0.2v is raised from stock). Maybe I just haven't added enough to it. I'll keep trying and update this thread.

[AVMPerformance]

Thanks for all the replies. That is the way I understand the TB airflow model to work as well (If you look at my tune, the 0v-0.2v is raised from stock). Maybe I just haven't added enough to it. I'll keep trying and update this thread.

Also correct the fueling around that area. it could also be hanging if the fueling is trying to adjust, just a thought

[Moparmaniaccuda]

What should I be correcting it to? When I turned off DFCO and closed loop, my EQ error indicated I was 8 percent lean in that area...doesnt seem to be that far off to me. FYI I'm using an LC-2 wideband, voltage offset corrected.

[coanan]

What should I be correcting it to? When I turned off DFCO and closed loop, my EQ error indicated I was 8 percent lean in that area...doesnt seem to be that far off to me. FYI I'm using an LC-2 wideband, voltage offset corrected.

Do some comparing. It's a 6.4 tune.

[Moparmaniaccuda]

Do some comparing. It's a 6.4 tune.

So the only issue I can see with that tune, is that he has -20 spark advance from 1800rpm all the way up to redline in the first three rows of his MBT, WOT, and PT spark tables. If I did that, my car would be popping and banging on decel...not sure how he's getting away with that unless he doesn't care. He basically did what I said I wanted to do in the beginning of this post (albeit tongue in cheek a bit as I realize it's the wrong way)...though he took it to the extreme.

He also blindly added ~23% to the entire TB Airflow table and 30% to the entire small/large desired throttle tables. Seems like throwing a dart.

Glad it worked out for him, but my guess is if he changed the airflow models and that -20 spark advance at the same time, the -20 spark advance is "curing" the rev hang/idle driving I'm talking about.

Should have a chance to continue tuning this tomorrow.

[coanan]

So the only issue I can see with that tune, is that he has -20 spark advance from 1800rpm all the way up to redline in the first three rows of his MBT, WOT, and PT spark tables. If I did that, my car would be popping and banging on decel...not sure how he's getting away with that unless he doesn't care. He basically did what I said I wanted to do in the beginning of this post (albeit tongue in cheek a bit as I realize it's the wrong way)...though he took it to the extreme.

He also blindly added ~23% to the entire TB Airflow table and 30% to the entire small/large desired throttle tables. Seems like throwing a dart.

Glad it worked out for him, but my guess is if he changed the airflow models and that -20 spark advance at the same time, the -20 spark advance is "curing" the rev hang/idle driving I'm talking about.

Should have a chance to continue tuning this tomorrow.

Never looked the entire tune over to pick it apart, just used the Idle torque spark and idle torque throttle as a base to get my car to idle without surging and dying, got it close enough so I could drive and tweek it.

[AVMPerformance]

So the only issue I can see with that tune, is that he has -20 spark advance from 1800rpm all the way up to redline in the first three rows of his MBT, WOT, and PT spark tables. If I did that, my car would be popping and banging on decel...not sure how he's getting away with that unless he doesn't care. He basically did what I said I wanted to do in the beginning of this post (albeit tongue in cheek a bit as I realize it's the wrong way)...though he took it to the extreme.

He also blindly added ~23% to the entire TB Airflow table and 30% to the entire small/large desired throttle tables. Seems like throwing a dart.

Glad it worked out for him, but my guess is if he changed the airflow models and that -20 spark advance at the same time, the -20 spark advance is "curing" the rev hang/idle driving I'm talking about.

Should have a chance to continue tuning this tomorrow.

The Negative numbers in the first three rows are most likely what you thought, decel / off throttle "pops", done incorrectly but It wont affect any sort of rev hanging. AS for fueling, change in the VE tables where you are lean. 8% might seem small to you, but the ECU might be over / under compensating and contributing to the rev hang your concerned about. even if it isn't, I would just get it more rich then lean. Lean = ECU adding Fuel, Rich = ECU pulling fuel, I know you know this but I have had 10% fueling off affect rpm and idle...just a thought.

[Party340]

My car was doing that as well. I tried playing with those tables mentioned above as well with no luck. It started doing it when I zeroed my cam at part throttle cruse. Retarded the cam 5 degrees at part throttle (120 vs 125) and it stopped rev hanging. 426 Stroker comp 270. Don?t know if it will fix your issue but it worked for me. It might be a vacuum thing rolling idle vs stopped for idle. Retarding the cam will change vacuum for a given rpm. Who knows with these dodges. I also noticed that if your part throttle cam retard is set past the range of the limiter it will throw your cam out of wack at high rpms. I?m guessing it screws with the pid tuning being that the cam never hits setpoint.