4L603 Shifting Early

[spectre1995]

Hello all,

Trying to dial in problems I'm having with my 4L60E.

First off, it lacks power coming from a dead stop. I'm having to put in almost 2,000 RPM in order to get the wheels turning. Cruising on the road, it shifts through all four gears and ends up in 4th at 30 MPH. I have verified that my tire size and gear ratio is correct, and I have also cross referenced my MPH with other sources to verify the output on the HPT interface is accurate within 1-2 MPH.

Today it actually stalled as well, which has never happened before.

Attached is a copy of my current tune as well as the log file from today's test drive. Any ideas? I'm about ready to turn the 4L60E into a doorstop and find a good manual transmission to stuff back in there. Test Drive 9-28-22.hplExperimental Tune 6-27-2022 from 2005 Chevrolet Express 6.0L.hpt

[blindsquirrel]

You need to add Cylinder Airmass, Delivered Engine Torque, Knock Retard, Injector PW B1/B2, and probably more. But those to start.

Why is the changelog showing this was originally a 4L80E file (as expected for an Express 3500)? You think the 80E segments will properly control a 60E? Cause I don't.

[blindsquirrel]

AND you changed the platform type under System Options? You can't turn one OS into a different one just by changing settings like this!

[ECM] 755 - Platform Type: Indicates the Vehicle platform type. Changing this value is not recommended.

[spectre1995]

Did I misinterpret any of the advice you had given me in this thread?

https://forum.hptuners.com/showthrea...oo-Early/page2

[blindsquirrel]

Yes, you did. You flashed an OS to the wrong Service Number. Nothing in that thread about finding the right OS to work with the hardware changes that no longer matched the original OS.

I'm not touching your file, it's got too much messed up in it - but here's a file with the same OS ID you can use for a 60E segment swap.
Attachment 124681

I'd go back to the stock file, do the segment swap, and then only make changes that you can find solid evidence to suggest that's the right thing to do.

[spectre1995]

Got it, thanks

[Blurbo]

Was this ever resolved?