Not shifting... TPS...TCU...etc...

'88 4.0 aw4

Well the jeep had been shifting erratically for a while, acting like it was spooling/revving while cruising at 40-50mph... changed the tranny fluid and it seemed to help but still did it.

Fast forward to a week or two ago when I parked it and didn't move it until today when I left for work it seemed to be stuck in 4th... and no Overdrive.

I was able to drive stop and go by shifting manually which it seemed to handle fine.

Got home did some searching/reading and went outside and found the TCU fuse was toast... replaced it... no change... replaced the TPS... and it ran like a raped gorilla for 1/2 a block or so then went back to goofy weak gearing. Then changed out the TCU... no change. TCU Fuse is still good.

2 questions:

How important is the actual adjustment of the TPS? Possible that I just need to adjust it?

On a Renix ECU, is there a "learning mode" where I have to drive it for a bit before the computer figures out where to shift or is that strictly the TCU's job?

ideas? suggestions?

p.s. It rained quite a bit in the week or two it was parked...

:dunno:

OK...aside from the obvious "Go search!!" =P

Yes, TPS adjustment is incredibly important with the Renix motors. If you haven't adjusted it, jump on it (search for details).

It's been hotly debated whether Renix motors have a learning curve or not....but I found that removing the neg. battery cable for 10-15 minutes cleared the ECU settings, and it ran like a raped ape (still does, actually.....6 weeks later =P)