Boldkitty

Hi…I have an 02 E55 and recently started to have an issue. At WOT it accelerates to the limiter but the trans doesn’t upshift for a count of 2. The engine bangs against the limiter and it will eventually shift and do the same in the next gear. Casual driving has no issues. Checked the levels (hot/in gear/proper tool)and it seems ok. The electrical connector was replaced a while ago with no issues. Thoughts?

Thanks Bob

MattCordell

When mine did this it was due to a bad oxygen sensor causing violent upshifts.
As you have a newer car with OBD you should check codes to be sure what the issue is?

bbirdwell

Put it on STAR or equivalent and run a diagnostic. If nothing listed; log data and evaluate. The TCU will provide you much info on the health of the transmission. I've posted on this before. STAR or equivalent is required to diagnose and will walk you through the process.

Boldkitty

Thanks for the tip. No check lights, my 02 is a 38 pin….scanned..no codes…OBD scanned…no codes. I am going to have a local shop check the fluid level in case I read it wrong. Nobody near me has a STAR setup and the closest dealer does not seem too interested. I might search for a Indy with the setup. I only have a MB1 tool. Thanks

Boldkitty

Is the TCU specific to the car or will any EGS52 work? Thanks

Boldkitty

FYI…..the TCU and the ECU had different red lines so I was hitting the rev limit but the TCU didn’t think so. Getting a new TCU. Thanks all….