2014 JGC SRT - VCM Scanner Variables for Torque Setpoint

[R/TErnie]

Ok I'm going to preface my questions with a little background information.

I recently finished the installation and tuning of a Magnuson TVS2300 blower on my 2014 JGC. 6psi kit run on 93 octane.

Here's the Jeep on APR's AWD Dynapack dyno cell.


Stock versus 6psi Magnuson kit. 530awhp/480lb-ft. 93 octane SAE(J1349) corrected.


Then I took the jeep to the drag strip. Montgomery Motorsports Park.


Made 15 runs


My best run of the day [email protected] and also my best R/T of the day. Skunked the GSXR off the line and then he blew my doors off.


I got a best 60' of 1.763 by actually launching from about 600rpm.
The truck would consistently 60' between 1.85 and 1.90.

**End of Preface**

The truck felt like it would roll out under stock-ish power and then about 20 feet out it would go WOT and take off.
Logs show the throttle not opening up all the way until the truck rolled out about 20 feet...and closing partially half way through 1st gear... confirming my suspicion.

Screen shot of the launch log attached. My cursor is at 0MPH, just before the Jeep leaves the line. You can see the throttle closed and that there is a delay before it opens fully, and that it closes quickly part way through first gear. You can also see the transmission retard the ignition timing in first gear gear PRIOR to the shift.

My initial thought was to go through the logger and log all the torque requests to see what was requesting this reduction. Trace the issue back to what was causing it. So I looked through the available logging "channels" that have no graphical representation (just text with units and data on the left hand side of the logger) Nothing pertaining to torque requests in that... so I remembered that sometimes the logging feature (multi y-axis traces) had more options.
So I attempted to add several of these parameters to a Chart. So I right clicked, selected "Charts Layout", went to a group and selected it. I then clicked the add series button, and found several torque arbitration values including... Powertrain Throttle Torque Request. I was excited and ALL of the torque request chart parameters I could find. To my dismay, I could not log ANY of these items. When I clicked the start logging button the area where values would typically populate were empty. I played around with the display settings thinking that I had somehow made them not appear. However after adding other parameters and having them operate properly, I began to think it wasn't me.

The parameters I tried to add... are in the other attachment titled "parameters"

The logging of these parameters was to figure out what and why I was being limited. The solution to the problem is a whole different matter. I guess the proper solution would be to be able to control the transmission's torque requests and the ramp rate of how it lets the torque ramp in. That's not available yet, so I guess I wait... I suspect there are other ways around it, but I suspect they are somewhat hacks to get around the transmission's interventions. enlighten me please.

A few other things I noticed while digging...

1)
Engine -> Torque Management ->General -> Auto Trans TqMgt
Shift Tq Red - the values are 0 to 4 in the curve. Do these values represent an actual torque in lb-ft? Nm? minimum torque output allowed from the transmission? Or do the numbers represent a level of torque reduction?

2)
Engine -> Torque Management -> General -> Stall TqMgt
Brake on Torque/ Brake off Torque.

These values cannot be raised from their initial value of 967... furthermore they don't appear to actually be the arbitrated value used for Stall Torque Setpoint...because my throttle is closing at 24% on and engine that doesn't produce 500lb-ft.

Question!
In the torque management section there is a lot of reference to Use Spark A/B. Friction Incr A/B.
What does the A/B represent?

Question 2 - Can someone at HPTuners please share how the intake manifold Volume changes the calculated fueling? Basic equation to show how and when it changes the injected fuel mass. Is this just limited to transient fueling or does it also change the injected fuel mass during all conditions...and to what degree?

Question 3 - Occasionally the truck will idle down to 560rpm... so I logged the idle setpoint to see if it was actually requesting this rpm or if the PID controller couldn't hit it's target. Turns out the ECU is requesting an idle target of 560rpm. When I go through the VCM Editor software for Engine -> Idle -> RPM... NONE of the idle rpm setpoints are below 680 rpm!?!?!?! Where is this target of 560rpm coming from?

Thank you for your time and I look forward to your response.

-Eric

[R/TErnie]

The truck felt like it would roll out under stock-ish power and then about 20 feet out it would go WOT and take off.
Logs show the throttle not opening up all the way until the truck rolled out about 20 feet...and closing partially half way through 1st gear... confirming my suspicion.
Screen shot of the launch log attached. My cursor is at 0MPH, just before the Jeep leaves the line. You can see the throttle closed and that there is a delay before it opens fully, and that it closes quickly part way through first gear. You can also see the transmission retard the ignition timing in first gear gear PRIOR to the shift.

I'm going to try the Engine ->Airflow -> ETC -> "Throttle Max" settings and raise the allowed voltage relating to throttle position at all rpm breakpoints except idle. UPDATE: THIS WORKED!!!

My initial thought was to go through the logger and log all the torque requests to see what was requesting this reduction. Trace the issue back to what was causing it. So I looked through the available logging "channels" that have no graphical representation (just text with units and data on the left hand side of the logger) Nothing pertaining to torque requests in that... so I remembered that sometimes the logging feature (multi y-axis traces) had more options.
So I attempted to add several of these parameters to a Chart. So I right clicked, selected "Charts Layout", went to a group and selected it. I then clicked the add series button, and found several torque arbitration values including... Powertrain Throttle Torque Request. I was excited and ALL of the torque request chart parameters I could find. To my dismay, I could not log ANY of these items. When I clicked the start logging button the area where values would typically populate were empty. I played around with the display settings thinking that I had somehow made them not appear. However after adding other parameters and having them operate properly, I began to think it wasn't me.
The parameters I tried to add... are in the other attachment titled "parameters"
The logging of these parameters was to figure out what and why I was being limited.

After reading a bit, it would appear that I needed to check the "Show only parameters backed by channels" button. Otherwise you'll see a lot of supposed parameters that have no data behind them. Which leads me to the next question... are these parameters without channels real parameters for this ECU, but they're just not yet defined? Or are these generic "parameters"? Still doesn't help me figure out what is generating torque reductions.

Question 3 - Occasionally the truck will idle down to 560rpm... so I logged the idle setpoint to see if it was actually requesting this rpm or if the PID controller couldn't hit it's target. Turns out the ECU is requesting an idle target of 560rpm. When I go through the VCM Editor software for Engine -> Idle -> RPM... NONE of the idle rpm setpoints are below 680 rpm!?!?!?! Where is this target of 560rpm coming from?

After speaking with another tuner that has SCT software, there is a low idle target that is 560 rpm. Not sure what causes my Jeep to request that target idle rpm, but it does.

Other questions are still outstanding.

[R/TErnie]

My journeys have brought me to a new question...

Sensed MAP - Enabled versus Disabled.

when you used the sensed map, it's using the output from the MAP sensor for the airflow calculations. Which I understand and get fully. When you disable this function... What and how does it determine the MAP? what do you recommend using and why? I've tried both and I can feel a big difference in how the throttle feels (Sensed MAP feels sharp and touchy) (Sensed map disabled- feels very filtered and doughy) I'll have to look at the actual logs to see if I can see any obvious differences in the airflow numbers.

[Hemituna]

You are correct, Sensed Map is using output direct from Map sensor at all times.
But on these, you also have Calculated Map. C-Map is a filtered version of Map but only works up to 96kpa.
So on a blown application, once you are in boost - no more filtering.
Sensed Map disabled will drive smoother with a softer feel to the gas.

My journeys have brought me to a new question...

Sensed MAP - Enabled versus Disabled.

when you used the sensed map, it's using the output from the MAP sensor for the airflow calculations. Which I understand and get fully. When you disable this function... What and how does it determine the MAP? what do you recommend using and why? I've tried both and I can feel a big difference in how the throttle feels (Sensed MAP feels sharp and touchy) (Sensed map disabled- feels very filtered and doughy) I'll have to look at the actual logs to see if I can see any obvious differences in the airflow numbers.

[R/TErnie]

You are correct, Sensed Map is using output direct from Map sensor at all times.
But on these, you also have Calculated Map. C-Map is a filtered version of Map but only works up to 96kpa.
So on a blown application, once you are in boost - no more filtering.
Sensed Map disabled will drive smoother with a softer feel to the gas.

Thank you for the response.

It would seem though that the calculated map isn't just filtered... because by filtering the value... when the MAP increased quickly, there would be a delay (depending on filter used...but most filters) which would mean the calculated MAP would trail behind the measured map. What I see on tip in is that the calculated MAP is actually HIGHER than the measured map. So it would appear that it's not only filtered but they're using a predictive airflow model as well based on throttle inputs. (VW/Audi's have a function called RLP which does this)

Thank you for the input!!!! appreciate the help.

[Hemituna]

When I used the term filtered, I was looking for another way of saying messed around with

C-Map has an upper and lower limit from S-map and seems to be part of transient fuelling.

[R/TErnie]

When I used the term filtered, I was looking for another way of saying messed around with

C-Map has an upper and lower limit from S-map and seems to be part of transient fuelling.

Does "sensed map - Enabled" disable the transient fueling?

I really don't like the way the "sensed map - disabled" drives. Maybe that's because it enables the transient fueling and it's soo far off that it causes it to mess up during transients. i'll have to play with it some more.

[Mep_q8]

I would love to see the file and a full log. There does seem like there could be some work done looking at the limited scanner info.

Please post up, this would be fun to fix! I've just finished tuning a 2013 Dodge Ram 5.7 with the TVS and managed to keep timing at 14-16 degrees. It seems your getting a lot of knock and lots of timing being pulled.

[R/TErnie]

I would love to see the file and a full log. There does seem like there could be some work done looking at the limited scanner info.

Please post up, this would be fun to fix! I've just finished tuning a 2013 Dodge Ram 5.7 with the TVS and managed to keep timing at 14-16 degrees. It seems your getting a lot of knock and lots of timing being pulled.

Did you look at the log I posted, because there is almost no knock, at most 1.5 degrees of retard. Did you disable/raise the thresholds for your knock sensors? I bet you did!

[msinsel]

**End of Preface**

The truck felt like it would roll out under stock-ish power and then about 20 feet out it would go WOT and take off.
Logs show the throttle not opening up all the way until the truck rolled out about 20 feet...and closing partially half way through 1st gear... confirming my suspicion.


-Eric[/QUOTE]

i am experiencing the exact same problem i feel like i go it pauses and then takes off . i just ordered the hp tuner so ill retune jeep when i get it i hope to get rid of the problem .thanks for this i thought i was the only one

[HemiLucille]

Hey R/TErnie, I don’t suppose you still have the value of the Jeep’s old intake manifold volume, do ya? I’m doing the 6.4 intake onto a 345 and I didn’t know if not having that value could cause an issue. Thanks