cowboy450 Posted March 9, 2009 Share Posted March 9, 2009 Howdy all. I'm a noob here from Lyman, SC. I just bought a 88 4.0, Pukego BA10 tranny, 2 wd. I'm not new to jeeps as I also have a 88 YJ, 89, XJ, and 95 ZJ. The MJ runs great but above maybe 60 MPH when you let off the gas and cruise it seems to miss. Touch the gas the tiniest bit and it smooths right out. I have some RENIX experience from my XJ so I have a few sensors, etc laying around. I think maybe starting by cleaning the throttle body and IAC, replace the TPS with a known good one. All vacuum lines look to be in place but I'm going to go a little more in depth with them. It feels like a lean condition but I know that can be misleading. I'm fairly sure it's not electrical because if you hit the gas it smooths completely out until you back off again. Another thing I noticed a few hours ago was that my idiot lights had gone out. I whacked the fuse box and the blinked back on. After further checking I found the dreaded clutch master cylinder leak. What is the best way to clean this up? Carb cleaner and compressed air and check all connections? Thanks. Link to comment Share on other sites More sharing options...
Geonovast Posted March 9, 2009 Share Posted March 9, 2009 The carb cleaner would be your best bet, but if it's already started to corrode I don't think there's any way to reverse it. You may need to located a new box. I agree the TPS could be to blame. I'd also dump some injector cleaner through it. Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 9, 2009 Share Posted March 9, 2009 HERE is the test procedure for the TPS. You will need this to adjust a replacement properly as well if you do replace it. I would get some electrical parts cleaner instead of using the carb cleaner in the fuse box, but agree that if it's being affected like that it probably will need to be replaced. Link to comment Share on other sites More sharing options...
TNT Posted March 9, 2009 Share Posted March 9, 2009 The O2 sensor could also be the cause of a lean condition. It is what tells the engine if it is running lean or rich. Link to comment Share on other sites More sharing options...
maddzz1 Posted March 9, 2009 Share Posted March 9, 2009 When you clean the TB and IAC be sure to use TB cleaner and not carb cleaner Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 9, 2009 Share Posted March 9, 2009 When you clean the TB and IAC be sure to use TB cleaner and not carb cleaner...and DON'T get either on the TPS or you will be replacing it for sure. Link to comment Share on other sites More sharing options...
cowboy450 Posted March 9, 2009 Author Share Posted March 9, 2009 As I said I do have quite a bit of Renix experience. I pull the TB when I clean it so no problem with sensors. I have a spare TPS and do know how to adjust them. I think I will go get some different cleaner for the fuse box. I don't want to do anymore damage. Hopefully I have a spare O2 sensor. I'll do all that and see what happens. The truck has 225s on it and 5th gear really surprised me. It pulled really well. It crossed my mind that the rear end has been changed. I'll check and post what I find. Thanks everyone. Link to comment Share on other sites More sharing options...
Pete M Posted March 9, 2009 Share Posted March 9, 2009 I would use an electrical contact cleaner on the fuse box. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 9, 2009 Share Posted March 9, 2009 I would use an electrical contact cleaner on the fuse box. acually- thats where I`d start, because he already said it leaked..and the connections are loose- why chase obscurity when the problems are easy to find? running throttle up to 60, then coasting with eratic engine response- but evens out with minimal throttle input? TPS w/vac problem- recheck it at idle, + a hair- see if the throttle response wanders- if it wanders AT ALL, do a quicky check of the EGR valve- because if its leaking a hair of vacuum- or stuck- it will do exactly what your seeing- all day long. Too much air into the intake/lean condition. If the EGR chacks out as good- ohms check the TPS- look for the dead spot low on the scale- adjust as needed- reset. verfiy your holding vacuum- check the lines behind the battery box and down at the tank...you know this if your a renix head-its just another fun renix day. if you STILL have problems- time to check the electricals and start bypassing. :D hope the bulkhead connector is not trashed...if the juice is down there, it needs to come apart, and get cleaned....or it will self destruct later. Link to comment Share on other sites More sharing options...
cowboy450 Posted March 9, 2009 Author Share Posted March 9, 2009 Ok, fuse box is fine just needed a little cleaning. The bulkhead connector was full of something that resembled tar. I cleaned it out (by the way contact cleaner won't touch this stuff) with carb cleaner, packed with dielectric grease and reassembled everything. It may be a few days before I can tackle the motor. I dug up my spare TPS and O2 sensor so I will let everyone know. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 10, 2009 Share Posted March 10, 2009 Ok, fuse box is fine just needed a little cleaning. The bulkhead connector was full of something that resembled tar. I cleaned it out (by the way contact cleaner won't touch this stuff) with carb cleaner, packed with dielectric grease and reassembled everything. It may be a few days before I can tackle the motor. I dug up my spare TPS and O2 sensor so I will let everyone know. that "tar" could be a good thing...or very bad. If it looked like it was slathered on, was sticky, AND the plastic was not gooey OR brittle, then the previous owner had a neat idea and sealed it up- probably with urethane sealent- but...if the plastic was iffy...gooey...or the least bit brittle...you know the problem. The fluid has been in there awhile, and it loves to weaken plastic- it "can" cause a fire, or the problems you listed simply because of weak contacts. Some of the bone stock XJ/MJs Ive played with and worked on came from the factory with "goo"- but it was visible on the clamshell itself- stock sealent. usually hard as a rock- but with a little brake fluid/clutch juice, it turns to goo... Link to comment Share on other sites More sharing options...
tugalo Posted March 12, 2009 Share Posted March 12, 2009 My 88 does exactly the same thing, misses/skips badly at around 1800-2000 RPM with no load on the engine. Give it a little gas and it smooths right out.... I cleaned all the grounds, added some extra heavy-duty grounds and swapped in various sensors. the only thing that seemed to help it was the grounds and the Manifold Air Temp sensor. its better now but not perfect. Link to comment Share on other sites More sharing options...
cowboy450 Posted March 14, 2009 Author Share Posted March 14, 2009 Ok, TPS is ok but was out of adjustment. Throttle body and IAC weren't too bad. I found one very small vacuam leak. EGR seems to be working as intended. I hope to drive it some tomorrow and see how it does. I was wrong about my fuse box, it does have damage on several connectors. Anyone have one laying around they want to sell? If not I hope to find one next weekend at the Knoxville Pull a Part. I'm thinking just clip the wires about a foot from the box to give myself plenty of wire to work with. Link to comment Share on other sites More sharing options...
cowboy450 Posted March 25, 2009 Author Share Posted March 25, 2009 Ok, still haven't gotten to drive it, hopefully soon. New fuse box is in most of the way. I picked up a dash with gauges instead of lights. My head doesn't have a place for the new temp sender. There is just a undrilled smooth round spot there. No problem with that, I can drill and tap it but I have no wire. I thought Jeep used one harness, would the wire be tucked in the loom or something? If not how do I wire it? Thanks. Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 There has to be a spot for it, because that's where the sender for the light would be. Where are you looking? Should be on the back of the head on the driver's side. Is that where you're looking? Link to comment Share on other sites More sharing options...
cowboy450 Posted March 25, 2009 Author Share Posted March 25, 2009 Yep, back of the head, same place as my 89 XJ. There is a cast in boss there but it isn't drilled and tapped. Every one I have worked on has had a temp sender there. Got me puzzled. This motor is supposedly rebuilt, aftermarket head? Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 I wasn't aware of any aftermarket heads. I have heard that the newer heads (99+ I think?) didn't have it, everything ran off of the temp sender in the thermostat housing. The rebuilders may have not know what it was for and filled it in... I've seen crap like that from rebuilding companies. I wouldn't suggest drilling it out unless you're doing it with the head out of the vehicle, and it will be completely cleaned out before reinstallation. You don't want any metal shavings in your cooling system. Link to comment Share on other sites More sharing options...
cowboy450 Posted March 25, 2009 Author Share Posted March 25, 2009 It hasn't been filled, still a rough casting like the rest of the head. This is an 88 so I'm sure it's not a late model head. As for drilling, grease on the bit and the start the motor to let water pressure shoot out should take care of that. My biggest worry is wiring if I don't have one. I hope it is hanging around somewhere. Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 Hmm. I am baffled. :hmm: Link to comment Share on other sites More sharing options...
cowboy450 Posted March 25, 2009 Author Share Posted March 25, 2009 Ok, this bothered me enough that I just went and checked. My wire was hanging behind the valve cover so all is good. I don't think I will have a problem drilling the hole but it is still a mystery. Link to comment Share on other sites More sharing options...
500 MJ Posted March 25, 2009 Share Posted March 25, 2009 Newer HO head? Does your coolant hookup on the front of the engine have the sensor in it there? Link to comment Share on other sites More sharing options...
cowboy450 Posted March 25, 2009 Author Share Posted March 25, 2009 If you mean the thermostat housing sending unit, no but they would probably have put the old housing on it. I'm thinking HO head after doing some research. Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 If it is an HO head, it would have to be a later model one, my 91 HO has the temp sender there. Link to comment Share on other sites More sharing options...
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