I'm looking for some help troubleshooting what appears to be converter slip. I started working on a TCM tune to lock up the converter in 5th and 6th gear part throttle. We've tried several iterations but consistently get a shudder while cruising in 6th gear, 55-60 mph when commanding zero rpm converter slip. It did not shudder with the stock calibration that was commanding 20 rpm slip.
Vehicle
- 1976 C25 with an L92 pulled from an Escalade, and a 6l80 pulled from a police Yukon.
Engine mods
- BTR LS3 stage 3 cam
- Ported heads
- High ram intake, 102mm TB
- 1 7/8 longtubes
Driveline
- Circle D 245MM triple disk 3200-3400 rpm stall converter
- Stock 6l80 trans
- 3.73 gears
- 33" tires
The engine is controlled with a Holley Terminator X Max, there is no factory ECM on the vehicle. The Holley module can flash a basic 6l80 tune but not adjust TCC settings.
The stock read was pulled from the TCM. The OS is 24264923 which I think indicates 2013 camaro (based on a google search). But trans came from a 2008 police yukon. I'm not sure but maybe the Holley rewrote the OS?
These were the updates in the V1 TCM calibration
- Lockup disabled in gears 1-4.
- WOT lockup disabled.
- Regulator gain of 1 and offset of 0 to hopefully smooth TCC apply.
- Observations: shudder in 6th gear at 55mph
The shudder remained through several iterations of varying gain/offset/ramp parameters. One observation is that the shudder seems to resolve when commanding lockup through the VCM scanner.
Would you be able to review the tune/log and let me know if anything is clearly missing? I've done a fair bit of 6l80 tuning on my mostly stock silverado. But nothing quite like this.
I've uploaded the TCM tune as read from the TCM, and a tune with the V1 updates.
I've also uploaded a log file using the channels 7 config. Although we are only able to read available TCM parameters.