EUREKA

My factory bench seat. White was a questionable choice for a daily driver, thus the Mexican saddle blanket.

Thanks. The paint job was done by a friend of mine.

Thank you!

Something for me to look at, thank you.

Replaced and calibrated the TPS. Issue persists. It is very hard to make the symptom occur purposely. Happens most often between 30 -45 mph when cruising under light throttle, at a constant speed. Symptom is a momentary drop of rpms (indicated no tach) followed a slight lurch and sound of drivetrain coming back under torque. No difference in presentation when in 3rd gear. I have had a TPS fail in a way that produced a very similar symptom on a 97 XJ 4.0. Also had fuel pressure regulator as well as check valve in fuel pump produce somewhat similar symptoms on a 93 ZJ 4.0. I have tried to reproduce the symptom by slowly moving the accelerator through it's range with the truck in neutral without success.

Work truck at work.

1988 Jeep Comanche 4.0/AW4

They assure me it has dex iii in it.

Had it in to the transmission shop today. They are saying it's not transmission related, it is an engine issue. Possibly a dead spot in the TPS.

My IAC is a few years old. I think the brand is BWD.

It slowed down without warming up. The third time I started it, the idle speed was normal and it was still dead cold.

Well it happened again. Started the truck cold and it started instantly as it normally does and idled at 2000 rpms. The AC mode switch was set to vent but last month it stopped working anyway and is permanently on defrost. When I shifted into any gear the rpm's dropped to just over 1000, shifting back to park or neutral it returned to 2000 rpm. Turned the engine off and restarted, the same condition occurred. Turned the engine of again and let it sit for a few minutes. Then upon staring it is now idling normally. Maybe the IAC is sticking? Too intermittent for a vacuum leak I think.

Thanks!

Just wanted to check that Dex IV is backwards compatible? Looks like it is not.

Yes, but I have a very good impression of this shop owner. Nevertheless, I'll be checking this.

So the u-joints are all in great shape, and they should be since they are relatively new. Haven't looked at the TCM wiring yet, but I have needed to rebuilt the t-case mode indicator switch for years so I will do both of those this weekend (dash light indicates part time for a couple hours after I shift back into 2wd) I pulled the receipt from the trans shop from my truck folder and it was actually back in August of 2021 that I had it in. It reads "10qts ATF Jeep type". I'm going to stop by there next week and make sure that it was DEX, but I suspect that it was.

I'll do both those things.

Problem is not gone. Occurred a couple times cruising around 35 - 35 mph yesterday. I can't see anything wrong. I do feel that the problem initially only occurring after very hard stops should be diagnostic of something. All I can think is maybe the u-bolts holding leafs to the rear axle need to be tightened, and as I stop hard the axle is rocking downwards, placing the drive shaft in a bind. Haven't checked that yet, but I've never loosened them for anything. And now that it has occurred while cruising at a constant speed I'm not sure how that would make sense. Might just have to break down, tow it home when that happens, then I'll be able to fix it. Intermittent problems are the worst!

I had them do far more than a fluid change. A previous owner had installed a "clamshell". But you're correct a fluid change is easy, and I should have checked the level long ago.

I am fairly certain that I do not have any transmission fluid leaks. I park inside a garage with a concrete floor, and would have noticed any significant leak. I also just got under the truck and see no signs of leaks. I can't explain why/how I had no symptoms until the last few weeks, or why this issue only occurred after a hard stop. It could be that my problem is intermittent and will return, and that the low trans fluid had nothing to do with it. Maybe once the pavement is dry the problem will return. For now I can lock up the brakes and slid to a stop without the issue occurring.

After adding 2 quarts, I can't get the issue to occur today.

Right, like I said, looks like my local trans shop left it low last time I had it in there. Really pisses me off.

I definitely have no leaks. Test driving it today.