Upgrading my 1999 Suburban C1500 for better towing performance

**Kitch** · 05-13-2019

Try this - https://forum.hptuners.com/showthrea...Table-Software

**Machine_whisperer** · 05-14-2019

Originally Posted by Kitch

Try this - https://forum.hptuners.com/showthrea...Table-Software

AWESOME! Thanks! Digging in now.

**Fast355** · 05-14-2019

Originally Posted by Machine_whisperer

AWESOME! Thanks! Digging in now.

Sorry, I did not see your last post until this morning.

I did a 454/4L80E dually just this last weekend.

For the 4L80E I set it to lock under acceleration in 3rd gear and WOT lock in 2nd gear. Then in the PCM, I set shift lock flag to enable locked converter shifting. The OEM setup would not lock the converter until 63 mph in 4th unless you had the shifter pulled into 3rd or were WOT at which point it would lock in 2nd at 45 mph. The truck now cruises as low as 1,250 rpm unloaded around town. The stock 454 Vortec with the 4.10 gear has plenty of torque to move the truck around even down at that RPM.