I was wheeling on Saturday & noticed all of a sudden the Jeep was running differently. Sitting with it in park it idles fine & revs fine. On the trail, in drive, it stumbles/shutters. It does a very small amount in reverse too or it could just be my imagination.

When my wife & I noticed it I immediately got out & checked the exhaust system. Felt like it was flattened. Everything was fine. I then checked to make sure there wasn't a hole in the transmission pan. Thought it might have been loosing fluid. Nope.
We weren't too far from a town so I figured it would make it to a parts store & look it over.
From a stop, it would accelerate but like it had a bad plug or wire, transmission slipping &/or vacuum leak. Once it shifted out of 1st gear the issue went away. One time it did it in second also. That, or it never shifted from 1st. Not sure.
I figured that as long as we maintained highway speed we'd be fine. So we hit the road & didn't have any problems until we stopped for food. But once back on the interstate, it was smooth sailing.
We made it home just fine. Since then I've
- added a pint of ATF
- pulled each spark plug one at a time while running
- pulled the air filter
- checked for vacuum leaks
- checked fuel pressure (31 & 39 with vacuum line off)
- cleaned the throttle body & IAC
- replaced throttle body with a spare that contained it own tps, IAC & whatever else was on it
- replaced the fuel filter

None of the above had any affect on the issue.
What am I missing?

It's a 89 I6, automatic with a bone stock engine & 25x,xxx miles.

I did plugs, wires, cap & rotor button about 5k miles ago.

 

Swapped the coil from the parts Heep. Still not right. I'll do a tune up tommorow & swap computers if the former doesn't fix it.

 

http://cruiser54.com/

 

Yeap, I've read over those before but unfortunately none of those are helping me diagnosis my problem.

 

Doing them can help greatly help..Find cause of problem.

 

David, Check the injector harness where it goes from the firewall to the head for chafing.

Also wiggle the injector plugs at the injectors.

And, you should really DO Tips 1, 3, 4, and 5 at some point.

 

Thanks guy, I'm just getting frustrated with this. Thank goodness it not my dd.
I'll checkout the harness & injector plugs. Probably throw the tune up stuff on after I test the other

 

I could tell.....LOL.

Make sure the CPS wire isn't hitting something when the engine torques also.

 

I was going to pull a injector plug one at a time while the engine was running but never thought about the TPS. I think that was the issue. I wiggled the wires for it & the injectors & SUCCESS. It runs like it use to.

The wires on the TPS on there are mushy. I'll pull my spare TPS & install it after I relax, get a drink, let the Jeep cool off & watch some football. I'll also do steps 1, 3, 4 & 5. I've been putting it off.

Thanks again guys for the help.

 

woohoo!!!!

 

Victory!

 

My '89 Renix does this sometimes as well. I always just check the connections and my injectors, actually physically touching them, disconnecting and reconnecting, and the issues has always gone away. These Renix Jeeps are really gettin' old!

 

Agree.
I plan to swap out the engine/trans/tcase with one with 100k less miles. I'll look into getting a new harness then.