Kris smith

Ok lil back story I have a 90 4.0 auto with 231. 4.56 lockers and 31s. The last month or so I have had a long crank (maybe 3-5) seconds and some times when it does start it revs to about 1500-2500 rpm for anywhere from 2 seconds to 15 seconds. That's problem 1. Number 2 is when I have the switch in comfort mode( I don't normally drive with it in that mode ) it seems to shift into od with a slip. And 3 it always seems to want to shift to the hugest gear possible as soon as possible. I'm thinking this is a tps issue. I haven't checked the voltage of the tps yet but I have check everything else at some point in the last 3 months. I have perfect sensor ground new CPs new fuel pump relay all contacts have been cleaned. Any help fellas

1976Mustang

Not the throttle sensor. If that went bad, the engine would start fine and hesitate under load. but that sensor has nothing to do with the transmission. I'd start with testing your Crankshaft position sensor, and the camshaft sensor. Those are among the most common issues.

The transmission knows where the throttle is via cable, if the Renix motor it setup the same, it's the one closest to the front of the engine in the T/B. As for adjusting it, no clue on this motor. I'll let someone who knows the Renix tell you.

cruiser54

Huh?

The TPS on a renix has 2 sides. One for engine. One for trans. HO uses the same TPS harness for both functions.

The TV cable is a Throttle Valve cable which ONLY increases the trans pressure the higher the throttle opening.


Bypass that stupid Power/Comfort switch and adjust the TV cable. How long since you last changed trans fluid? Ever do Post 10 in my tips?

Kris smith

I haven't changed it since I've owned it but that's been 4 months. The fluid is full it's red and smells fine. I just keep the switch on power. I just don't want to be smoking a tranny it's my dd. been thinking when I get time to collect parts for a 5 speed swap. Like my manual better than the aw4

Kris smith

I have not done 10 never even thought about it as I have always have had a manual jeep

cruiser54

If the 7.5 amp "trans" fuse is blown in the fusebox, or if the P/C switch is bad, you will be stuck in Comfort mode.

cruiser54

Here:

Bypassing the Power/Comfort Switch on a Renix Jeep

Remove and unplug the switch. In the harness are 3 wires One has a stripe, one is tan, and the other black. Make a 4" jumper wire with a male spade at each end. Plug one end in the cavity for the tan wire and the other in the cavity for the striped wire and you'll be in permanent Power mode. Stuff the harness back in and reinstall the switch for looks.

If you happen to have a 91 or 92 XJ/MJ and it has the Power/Comfort switch, just jumper the Tan and Blue wires in the harness plug.

NEVER include the black wire when jumpering!!!

Kris smith

My switch works fine. There's a noticeable difference between on and off. The reason I suspect the tps is in my 88 5 speed I had since the day I got it I had starting issues and high idles and low idle. After a while It go bad I put a new tps in and adjusted it and it was fine. But that was with a manual I Dont Know how an auto reacts to a tps going bad

cruiser54

Reacts same way.

What you need to understand is that the auto TPS is 2 different TPSs in one. There's 2 separate sections of it. One's for the engine and one's for the trans.

Doesn't mean both sides aren't bad though.

Always adjust it on the Engine side as it's more critical an adjustment than the Trans side.

Kris smith

Ok I will do that and clean that trans plug thing.

cruiser54

There's 2 plugs there.

Kris smith

Ok I will do it when I go back to work Nd can get her on the lift