jeephack Posted November 9, 2007 Share Posted November 9, 2007 I know that this has been discussed numerous times before, and I have tried to read all of the posts on this that I could find. I have a '87, 4 litre, 5 speed. I cannot get it to idle properly. I have checked all of the vacuum lines for leaks. Everything seems sound. I have changed the map sensor, cleaned the throttle body, even changed throttle bodies. Have checked the TPS. 4.98 volts at the harness connector. TPS is set at .82 volts at closed throttle. Will increase in voltage to 4.96 volts at WOT. When I start the vehicle...3000 rpm. Occacionally it will idle properly when it is cold. Once it warms up... 2500 -3000 rpm. Sometimes, I can punch the accelerator and the rpm's will drop. Any ideas?? Jeephack Link to comment Share on other sites More sharing options...
87mjdriver Posted November 9, 2007 Share Posted November 9, 2007 coolant temp sensor, in the side of the block under the headers, thats what it was for me and I replaced the same sensors you did Link to comment Share on other sites More sharing options...
Eagle Posted November 10, 2007 Share Posted November 10, 2007 Try cleaning the idle air controller. Also, consider the throttle linkage. Yeah, I know -- it's a cable. Well, actually it's a cable that connects to a linkage. Stand on the driver's side of the engine bay and look down between the block and the inner fender. Below the exhaust manifold there's a bellcrank. Twice with my '88 XJ I have had to liberally spritz that bit of linkage with penetrating oil to free it up and cure a sticking throttle. Link to comment Share on other sites More sharing options...
Oizarod115 Posted November 10, 2007 Share Posted November 10, 2007 check the adjustment screw at the throttle linkage, it'll change things a little bit, somoene might have cranked it way up because something else was ill-adjusted Link to comment Share on other sites More sharing options...
jeephack Posted November 19, 2007 Author Share Posted November 19, 2007 Just a quick update and many thanks to Eagle for pointing an old dog back to simple basics. Though the throttle cable in the engine compartment was fine, once I traced it back into the cab and under the dashboard, I found that one of the electrical harnesses had migrated south and was lying across the cable preventing it from fully retracting. Once the wayward harness was relocated, the truck idles just fine. :D Thanks again, Jeephack Link to comment Share on other sites More sharing options...
jeephack Posted December 3, 2007 Author Share Posted December 3, 2007 Well---not being one to let well enough alone for very long, I have created another problem that maybe you guys can help me with. Been reading about bored out throttle bodies, and since I had a spare one lying around, I thought I'd give it a try. Bored it out to 60mm. Cut a new throttle plate. (16 ga. polished stainless!) Everything went back together fine. Bolted it on the 'Manche and now it idles at around 3000 rpm. Are there adjustments that have to be made for the larger throttle body opening? I must make this thing work!! It sounds and feels awesome when you punch the throttle!!! Jeephack Link to comment Share on other sites More sharing options...
Twisty Posted December 3, 2007 Share Posted December 3, 2007 Still sounds like an IAC problem. My MJ will rev to 3000rmp from time to time...and doesnt appear to want to come down! Link to comment Share on other sites More sharing options...
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