trans wont go over 45mph?

i have a buddy that owns a 90 cherokee doesnt really know whats going on and i dont either. his trans will not allow his truck to go past 45mph does anyone know if this is completely the cause of his trans or would something else be cause it ? thanks

also he explains it as
It won't go over 45 mph. Its weak in the gas pedal like its straving for gas.

Plugged cat.

The throttle position sensor could also be suspect here. Not only is it important in allowing proper throttle tip in, it is DIRECTLY involved in the shifting characteristics of the AW4 transmission.

I'd suggest at minimum that you have that TPS tested.

thanks for the adivce guys im gunna shoot him an email

I had very similar symptoms and it turned out to be a bad fuel pump sending unit. You can rule this out (as well as potential clogged fuel filter) by checking fuel pressure at the rail.

TPS. I've seen the exact same thing before in a friends XJ. I still have the 'spare' AX-4 I picked up at the yard to replace his transmission he swore was gone. Definitely check it before getting anything else done.

Plugged cat can also do, but you will probably hear a god-awful sound around 2500-3000 rpm as exhaust gas starts blowing out the gasket and any other place it can!

I'll throw another vote in for the tps, especially since a 90 would be a renix and the tps is adjustable.

I fought that problem forever on my 87, liked to drove me nuts. I tried everything in the book first, as I was new to Renix jeep repairs, worked on the engine, the exhaust, the transmission, many of the controls, then it turned out to be a bad TPS on the transmission TCU side of the TPS (the side that the old renix manuals never mention testing until about the 1990 FSM). It also had a bad, poor ground on the TCU side of the TPS, which together had it upshifting at 1100 rpm at WOT, so I was in 4th gear at about 25 mph! Took about 3 minutes at WOT just to reach 55 mph! New TPS and new ground wire for the TPS (new ground on both sides!!!!!!!!!!!!!!!!!!!!!!) fixed all sorts of issues.

Search for my old thread "The RenX Files" for the story and the data on testing the TPS first with a multi-meter, ohms and volts.