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Discussion Starter · #1 ·
OK guys, first of all I am new to this forum and look forward to being with you all for along time. Now; I just picked up a 95 YJ 2.5L and upon start up it idles rough, around 500 RPM. After a few seconds it smooths out but the RPM keeps climbing and stops at about 1800 RPM. I started with checking for vacuum leaks and cleaning the IAC. When I pulled the IAC it looked clean but I cleaned it anyway just for good measure and scrubbed the throttle body. That did not help so I replaced the TPC. After replacing the TPC it seemed to help some but the RPM would still climb to about 1600. Next I replaced the MAP sensor. When I did that it still had a rough start but it did only climb to about 1200 RPM, but the kicker is now it has a dead spot and stalls when i step on the gas. Oh, I also replaced the o2 sensor. Any ideas would be greatly appreciated. I am considering going ahead and replacing the IAC even though it's clean. Sorry to write a book but i wanted as much detail as possible for you guys.
 

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Discussion Starter · #2 ·
OK. No parts stores open close by today so i can't pick up a new IAC. Just for giggles I unplugged the new MAP sensor that I installed and everything smooths out as far as the stall but still has a high idle. Could it be the computer?
 

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sounds like maybe an air leak where the exhaust manifold attaches to the engine. That will give you the higher rpms, but the stalling sounds like one of the vacuum hoses that attaches to the manifold
 

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Double check on vacuum leak, especially the rubber fittings at the manifold. i had one cracked on the bottom of the fitting and overlooked it several times. It wasn't until I removed each one and carefully checked them that I found it..
 

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Discussion Starter · #6 ·
Thanks guys. I will go back over and check the manifold and the lines for leaks again. I just keep thinking that if it was a vacuum leak that it would idle high on start up but it doesn't. It will slowly creep up as it warms up. I did notice that the temp gage is not acting right. Do you think by that not working correctly that it is sending the computer/sensors false information?
@DMCG the odd thing is that i can unplug the new map sensor and the stall disappears, it just still idles high. I put the old one back on and no stall just high idle. Wierd huh.
@airborne*yj I already replaced the TPS and just found out today that the guy i bought it from also replaced it about a month ago along with the IAC.
I will be back at it tomorrow. I am pretty certain that i am over thinking this. When i finally fix it i will probably kick myself because it will be something simple.
I appreciate the help guys!
 

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Discussion Starter · #8 ·
Yeah i actually did that a few times. Every time i messed with one of the sensors i disconnected to reset.
 

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with what you described with the map sensor, it sounds like new one might be faulty, but I still think its a vacuum leak somewhere
 

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Discussion Starter · #10 ·
dmcg you were exactly right. It ended up being a vacuum leak but not the typical leak i was thinking of. I was going back over all the lines again this morning when by pure accident i noticed the manifold bolt closest to the fire wall was actually backed out and i could turn it with my fingers. Ended up being that all of the bolts needed to be snugged alittle bit. I guess as the engine warmed the manifold expanded and created the vacuum leak hence the creeping of the idle. Tightened em all down and now it is purring like a kitten. I told you that it would end up being something simple and yes i am now kicking myself. Anyway got that done and now it's on to the fun stuff. Lift is next!!!!
Thank you guys i really do appreciate the help.
 

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Discussion Starter · #13 ·
oldmuddy this forum is the best! And yes JEEP people are great. Not often do I see people offer help like I see here.
 
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