Cabz Posted February 24, 2006 Share Posted February 24, 2006 One of the only issues I have with my MJ is getting worse. Ever since I have owned it ( and put the new engine in ) the engine breathes, The idle will go up and down about 250 rpm's up and down up and down lately it has taken to stalling when I push in the clutch at higher speeds ( in the process of slowing down ) any Ideas what it could be? I have had it on a scanner and everything shows normal. most every sensor is new Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2006 Share Posted February 24, 2006 "Most every"? throttle position sensor? MAP sensor? Did you adjust the TPS? Small vacuum leak somewhere? Scanners are really only useful on 91+ MJ/XJs. The old Renix Jeeps are easier (and at the same time, harder) to work on. Jeep on! --Pete Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 Tps is new, map sensor swapped out several times ( for giggles ) vac leaks no :? I was a little nuts checking for vac leaks when I Modifyed the intake to work on the H.O head so I know I don't have any of those . I have a 91 HO engine running the Renix FI system with ford 19LB injectors just to clarify a bit more. I just unhooked the EGR solinoid and vac sensor on the air cleaner to see if I had an issue with one of them , I will drive it tommorrow and see the MJ also has a new O2 sensor CPS idle speed control solinoid. Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2006 Share Posted February 24, 2006 I seem to remember someone saying that a new TPS needs to be "set". Jeep on! --Pete Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2006 Share Posted February 24, 2006 What about a leak in the manifold gasket? Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 I seem to remember someone saying that a new TPS needs to be "set".Jeep on! --Pete They do :D , I set it with a friends snap on MT2500 scanner . Thats when I checked everything else and found everything to be working to spec :? Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 What about a leak in the manifold gasket? Nope :D after I had the intake modified I checked that area thuroghly no vac leaks anywhere. The breathing has been an issue as lokng as I have owned the ole girl, and to this point it has not been an issue. it seems like ever since I had to change the CPS it has been a little squirlier than normal. It might just be time to reset the PCM Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2006 Share Posted February 24, 2006 What procedure are you using for leak detection? Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 wd-40- carb cleaner- and a rather fun way :shock: by useing acetelene gas with a hose it works the same as wd without the mess . I alos had amanifold vac gauge hooked up the whole time to eyeball and changes in vac I have also read the plugs a dozen times and they show a perfect tan tip on all 6 no white/gray from being lean . Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2006 Share Posted February 24, 2006 I'd heard of that same technique using propane, but I guess you've covered all the bases. Seems you've got a real head-scratcher there. :? Jeep on! --Pete Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 Yup :-D I think I am going to try and adjust the idle speed up a hair and see what that gives me . Link to comment Share on other sites More sharing options...
87manche Posted February 24, 2006 Share Posted February 24, 2006 Have you checked the IAC is operating properly? My MJ would die after a downshift and engine braking when I pushed the clutch back in. The IAC was all gummed up and not moving quick enough. I took it out and cleaned it up real nice and it hasn't stalled since. Something too look at before you go messing with the idle screw. Link to comment Share on other sites More sharing options...
Cabz Posted February 24, 2006 Author Share Posted February 24, 2006 Have you checked the IAC is operating properly?My MJ would die after a downshift and engine braking when I pushed the clutch back in. The IAC was all gummed up and not moving quick enough. I took it out and cleaned it up real nice and it hasn't stalled since. Something too look at before you go messing with the idle screw. I tried replaceing that as well, I actualy pulled the TB and scrubbed the snot out of it :D Link to comment Share on other sites More sharing options...
Cabz Posted February 28, 2006 Author Share Posted February 28, 2006 I think I may have this one solved . Pete you where right about the vac leak :-D Just not on the engine , The vac booster for my brakes has a nasty leak ( can you say 96 XJ brake booster/MC upgrade time :D ) this is causeing a high idle sometimes. Also when I got the MJ the old owner had adjusted the alllen screw to adjust the idle ( engine on the way out ) . I think what is happening to make the MJ breath is that the allen screw is still not set right , but the TPS want to keeps the jeep at stock idle rpm . what the TPS is doing is adjusting the idle speed and when it gets to idle speed it slacks off ( PCM wise that is ) then the idle drops a hair and it starts all over . thats where I am so far Link to comment Share on other sites More sharing options...
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