I noticed my lock-up wasnt working yesterday or today. Is there any kind of temp the engine or trans has to get to or it wont engage? I ask because my buddy had stuck a 165 stat in it and put a big trans cooler on it because he didnt like how hot it was running. So it doesnt run any hotter than that right now because its got chilly outside. I know he also replaced all the solenoids in the trans right after he got it. It has 130K on it now. This was at a little less than 100K. I'm going to try the lifting the brake pedal thing on the way home tonight. It usually engages a little before 45mph and the RPMs drop to about 1250. Its now running at about 1750. Also, I know some trans are different and I dont know how these are but does the locak-up not funtioning damage the trans. Some trans it doesnt matter but others it affects the fluid pressure and they will burn up.

 

The tranny will run hotter because now your tc is constantly slipping just a little bit now. It does that on all vehicles that dont have a locking tc. The difference is those vehicles were designed to keep the tranny fluid cooler. You will notice a difference in mileage! I would say about a couple miles to the gallon on a stock xj. Whether or not it's going to handle the added heat probably depends on how you drive. Some guys say theirs burned up and other say it wont hurt anything. There are mods you can do in fact to control it manually. Another thing to try is the throttle position sensor and the adjustment on the downshift cable at the throttle body. You can find how to do those by searching here.
Good Luck

 

Alright thanks. I tried the brake pedal thing I seen and that wasnt it. Also, the trans shifts fine and the check engine light isnt on. Would the TPS or the lock-up solenoid cause the cel to come on? Off to try some more searching I guess.

 

I was going to test the tps but i'm running into an issue. I'm thinking the tps is the plug on the northwestern corner of the throttle body. Its the only four wired plug I seen going into it. But, you cant stick the probes of the multimeter into the back of the plug like the instructions I found. Do I have the wrong plug? I was loosing light fast but I think tomorrow I will try getting the rubber out of the weatherpack connector and maybe I can do it that way.

Where do I test the resistance of the tcc soleniod at? I found instructions for that that say what wires are which but where do I find them? Or do I just crawl under the Jeep and find the plug and test there?

 

Bump. For some reason it worked again on the way to work. But didnt work when I left. I didnt get a chance to try adjusting the tps. My buddy said I was looking at the wrong plug anyway.

 

I know on mine the tps isn't adjustable, but on yours it may be. I don't remember what year they changed them. It should only have 3 wires, not 4. I don't want to give you wrong info because I've only dealt with 99's and 00's. As far as the solenoids, you can get to the wires at the transmission control module to test resistance or by removing the pan and filter. Again, on mine the tcm is right above the foot feed, on the older ones I think it is under the glovebox. Sorry I can't be of more help! A Haynes manual would give you the location of both. For $15 it's worth having. Not as good as the factory service manual but still worth having.

 

I bought a Haynes today. But the lock-up also worked today again. All day. I talked to my buddy that I bought the Jeep from and he knew it had been doing it every once and awhile but never thought anything bad of it. He also said, he's a certified mechanic, that he has never heard of a tps going in and out. When they go they just go. I determined which sensor on the throttle body is the tps. I was thinking it was something else just because it was a 4-wireed plug marked with a ABCD like the instructions I found online had said. As long as the Haynes covers the HO we're good. I havent looked through it yet. I know from looking at another thread what I should expect for resistances, just have to look in the manual to see if the tps is adjustable on my particular year and the location of the tcm.

I miss the simple holley and hei dizzy on my other car already. It might not have been effiecient but it was too simple to have issues.

 

I know one thing for sure, they can develop dead spots in them. When you test the voltage while opening the throttle, sometimes at certain spots your meter will act like it's losing ground. I would have a hard time believing the h.o. would use a different tps. Just look up the part number online for the two different engines.

 

I couldnt find nothing about the tps or tcm in the Haynes. They pretty much say, for the automatic, to take it to a shop because its WAY to complicated for self-mechanics. What kinda crap is that? Also, if the tps on a 96 adjustable?

 

Actually it really could be related to the 165 degree T-stat. The PCM was not designed to run the engine at that temp, so its entirely possible that the computer thinks the engine is still cold, especially on the cold days, and may even keep the engine running in open loop mode. like if you go into work in the morning when its cold the engine may not get into the proper temp range with that T-stat, however after work it may be just warm enough to get things working right.

The lowest T-stat I would advise in any street driven rig is 180, and preferably the stock T-stat on a computer controlled rig. Lowering the engine operating temprature greatly impacts fuel efficiency and longevity, yes a T-stat that is lower temp that stock will lower the lifespan of the motor. A lower temp T-stat will not help a vehicles overheating problems (tho it may take a few degrees off the tranny through the water/oil heat exchanger).

Anyhew I'd advise installing a stock temp thermostat and then checking out the lock up.

 

It was working the opposite. It would work in the morning when it was cold but then not work in the afternoon. But I cleaned up the throttle body and readjusted the throttle valve cable going to the trans again and now its been working the past couple days. Whenever I get the chance i'm going to do the same thing I did in my SS. Install a factory rated t-stat and drill two 1/8" holes in it. And maybe add an axillary electric fan or run the factory elec fan so that it will also run with a toggle switch. It really helped any problem I had with the SS getting too warm while setting in traffic.