Automatic Choke Adjustment

No choke on the Renix Fuel Injection. :-) Clean and treat the electrical terminals for the TPS and the Air Stepper Motor. You also might want to clean up the Throttle Body and Air Stepper Motor.

Also in your case make sure the accelerator cable and the throttle linkage are not binding.

We had that issue with out 88 Cherokee 4.0.

It also would stall at the first or second stop in the morning.

That was caused by a dirty plug on the TPS or throttle position sensor on the throttle body.

These plugs are only low powered computer plugs and the slightest dirt makes them shaky.

I used a proper electronic contact cleaner the first time on it and it lasted a couple years. The second time it went and stayed at high revs way off road so I used WD40 on it. That has lasted almost a year to and my wife just mentioned it needs another clean soon.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Fam_Petterss>

I don't know if the TPS is the real culprit on the 88 (Renix) system or not. No matter what I do mine will still stall after a cold start if I take off down hill and use the engine to hold it going down with my foot off the gas. If I tap the gas just before I stop, all is well; otherwise it will stagger and frequently die when I put the clutch in. I'm about convinced that it's a characteristic of the computer where it's over-correcting for the engine braking and not responding fast enough when it tries to get to an unloaded idle state. If yours is like mine, when it staggers and doesn't die it surges pretty good before settling down. Blasted nuisance, whatever it is.

No issues like that on ours.

When I clean the contacts, it purrs like new again for a year or more.

You 'can' use a volt meter and check the TPS out. I think you can also ohm it out, but the book test is for volts.

You need the key on and engine off, AC off and you back probe the TPS plug with the meter probes looking for volts. Use the center wire and either outside wire. One will be a mirror image of the other for readings. One side is for the auto tranny.

At the idle setting on the throttle lever, the TPS should read greater than .02 volts or 200 ma. One setting says .026 volts for the pre 91 adjustable ones.

At full throttle, it should read less than 4.8 volts.

The volt rise or drop should also be smooth, not jerky.

Same if you have it unplugged and are using ohms. The rise or drop in ohms should be smooth.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Been thru all that. I can almost predict when it's going to stagger at the bottom of the hill anymore - it seems like it always happens on a cool morning. Almost never happens when it's hot or actually cold (like freezing or below) but in that middle ground it's fairly common for me. I just live with it.

Thanks, I have used WD40 and also cleaned the throttle body,

I noticed that my throttle body is not exactly the same as described above link. It sure was dirty, and I did my best, it looked much nicer when I was finished, but right after the work, it started with high rpm again. So I guess it is another thing I have to get used to.

Thanks, I will try to measure later today.

You 'can' remove the TPS and clean the insides of it out.

Same for the passages in the throttle body.

Mike

"Geir R.Petterss>

Long, involved story, but when I got my MJ the throttle body looked like someone had baked the crud on. Every passage and opening was plugged. After cleaning the TPS and it's connector, I pulled the IAC motor and cleaned the motor shaft and inside the port. Both those helped. It took a wire to clean out the MAP port which made a big difference. I finally got PO'd and pulled the throttle body off, stripped it, and ran it thru a solvent bath in an ultrasonic cleaner - it was that dirty. Like Mike, I have to pull and clean the TPS connector every so often anyway.

Hey Mike,

I've heard you mention this quite a bit... Is there no way to "tape-up" the connectors to prevent dirty from getting in? I know there are anti-oxidant products out there....but they might be messy.

The best I have found is to use dielectric grease on the seals. Still when they get old they do get shaky and need to be cleaned.

I have seen folks recommend tossing out the CPS connector and just soldering the wires together because it is so common for the plug to crap out. It sits right on top of the exhaust manifold and dies easy.

Mike

SB wrote: