DFCO Table/Acceleration Based

[PurplePiss]

Can someone explain these?

Filter coeff
Accel Thresh
Accel Max

Is the car being limited on how fast it can accelerate? Or does it assume if the car accerlerates too fast that the wheels must be spinning (i.e. traction control)?

Also in that same area, what is Commanded Torque used for?

[PurplePiss]

ttt

[PurplePiss]

Hello? Bueller...

[Chris@HPTuners]

the quick help explains these values but here's a little more detail.

The RPM limiter has an acceleration based component that is used on some cals. It is meant to start limiting a little earlier on a fast accelerating engine to prevent RPM limiter overshoots. ie. to make the limiter more accurate on fast revving engines.

The Accell Thresh is the RPM below the RPM limit that accelration based limiting can occur. eg. setting this to zero means it won't occur and RPM limiting will occur purely based on RPM, not engine acceleration.

Accel Max is the maximum acceleration rate allowed before acceleration based limiting will occur (if the above condition is met).

Commanded torque is the amount of torque added or subtracted from the current RPM limit torque request (the RPM limit sends a torque reductiojn request to either the Spark, Fuel Cut or ETC code (which ever is selected). This makes the limiter softer for Spark and ETC limiting methods and allows the PCM to keep the car closer to the RPM limit when ETC and Spark torque control are used.

Chris...

[PurplePiss]

Thank you.

[RWTD]

the quick help explains these values but here's a little more detail.

The RPM limiter has an acceleration based component that is used on some cals. It is meant to start limiting a little earlier on a fast accelerating engine to prevent RPM limiter overshoots. ie. to make the limiter more accurate on fast revving engines.

The Accell Thresh is the RPM below the RPM limit that accelration based limiting can occur. eg. setting this to zero means it won't occur and RPM limiting will occur purely based on RPM, not engine acceleration.

Accel Max is the maximum acceleration rate allowed before acceleration based limiting will occur (if the above condition is met).

Commanded torque is the amount of torque added or subtracted from the current RPM limit torque request (the RPM limit sends a torque reductiojn request to either the Spark, Fuel Cut or ETC code (which ever is selected). This makes the limiter softer for Spark and ETC limiting methods and allows the PCM to keep the car closer to the RPM limit when ETC and Spark torque control are used.

Chris...

Chris, with that being said, does the C6 Z06 utilize any management system for acceleration and/or torque? I see these parameters within the calibration, but I wondered if they were active.

Also, are there any controls for the ETC system in regards to response time and actuator speed? I know the system is different than it used to be.

Thanks!

[Chris@HPTuners]

generally vette's don't calibrate much of this stuff.

There are opening and closing rate limits for the ETC, but generally they are calibrated quite fast.

[RWTD]

generally vette's don't calibrate much of this stuff.

There are opening and closing rate limits for the ETC, but generally they are calibrated quite fast.

Thanks Chris. That does help.

In regards to some form of "Torque Management" on the C6 Z06, is there any? I ask this because on another site someone stated this:

If he's still on the stock tune, the computer will induce torque management if he really hooks up. I think you can take him if you can shift.

I mentioned that I would check into this, and he stated:

You can check, but they are active. GM revised the rear not too long after the C6's came out, I think it was a change to the hub and axle shafts. They were breaking at a pretty good rate on regular C6s. I'm sure that was in their minds when they dropped another 100 HP in the car and wrote the TM strategy. I've never driven one but I hear they just bog if you really hook up well in first.

What would you gather from that?

[Joe_G]

I put 3:90 gears and headers on my C6 6 speed vette and I was hitting this acceleration based rev limiter in 2nd gear only. Drove all the experts crazy, including my tuner, who at the time was based on LS2 edit. I replaced plugs and tested wires trying to chase the problem, and was at my wits end. I found out via Corvetteforum about this accel thresh table in HP Tuners and bought Tuners to fix the problem. Which I did in about 10 minutes. My buddies and I have been tuning and loving it ever since.

Since then my tuner has purchased HP Tuners as well!

Here's my thread on the subject:

http://www.hptuners.com/forum/showthread.php?t=8611

[Bill@HPTuners]

yeah you gotta love all the adder/multiplyer tables that get thrown in there...and they arent all used on every car/truck so theres alot of searching/experimenting that needs to be done in alot of cases.