mcg355

I have a 1988 Camaro with a 5.3l and th400. The original 5.3 harness was modified to work with the original 3rd gen harness and a 4L60E. The original plan was for a 4L60E but I swapped a th400 in and now the pcm is searching for trans. Had a friend come over with HPTuners and he tuned it for a M6 which made the motor run much better but when you rev it up it will not go over 1200rpm. It acts like it has a major miss from 1200 to around 1800 rpm. To which it will not respond when you rev the motor at those toms. We have tried everything we can think of to tune it out but nothing works. Any help or direction would be greatly appreciated!

mcg355

Anyone know of anything like this?

gwtt

You could program it to run a manual but I think it still needs to see a vss.

mcg355

We reprogrammed it to think it had a manual trans in it and tried disabling the vss and not disabling it. Same issue occurred.

sowbelle

I had the same issue when you go to the trans section and select manual.
You need to change it to non electric trans or go to the manual trans section and change the abuse rpms. They are set to 1200 rpms from the factory.
Engine will run without a vss but better to have one or you will do a lot more adjusting on idle, dfco will not work properly and some other features. Dakota Digital has a trans speedo adapter to give the pcm some speed indication.

gagliano7

Here is a manual tune you can do a compare to

gagliano7

Here is a pic of the mode in the trans torque management section in hptuners

geo53psi

Try the following -

System Tab > PRNDL Equipped > Set to "None"

The go to the Transmission Tab > Auto Shift Properties > General tab> Trans Type > Non-Elec Auto