1987 xj throttle position issue

keeps acting like the throttle is stuck on my 87 xj 4.o auto...its not the cable or any of the linkage...guess its a sensor...any ideas which one???

i got this truck in trade for a carb...its got 250k on it...runs great other than this issue...

thanks

Could be a worn or glitchy throttle position sensor (number one suspect I think), or idle air controller (little solenoid in throttle body) sticking. Could also be a wiring issue that would be helped by cleaning connectors and plugs. Try cleaning all the connectors first, since it's essentially free. Finally, don't discount the linkages. There are two places where my old 87's linkages went wrong with this result. First, make sure that the pivot on the accelerator pedal itself isn't sticking. Second, make sure that the bell crank on the side of the engine, which carries the linkages to the throttle body, isn't worn and sticking. ON mine, the pivot was so badly worn that it would bind, even when lubricated. I couldn't get the stupid rusted torx bolts off (and my daughter was about to sell it anyway) so I just added a spring to the linkage to pull it back harder.

I had similar thottle sticking problems on my 87xj. The bellcrank assembly was worn out but the big culprit was the throttle cable. The cable had cut a track in the plastic sheeth and occationally would stick. After I replaced both, the car ran much better and throttle responce was improved. I suspect that the throttle position sensor was not getting it's full range of movement.

While your at it, you might as well clean the throttle body and intake to the air box.

thanks...guess i'll get a new cable to start...

before you spend money on a cable, disconnect it and see if it idles down. cleaning the throttle body and iac motor ports is cheap and easy. if that doesnt help. then probably has a bad tps. thats when it would be a wise investment to have someone with the scan tool to properly install and adjust it if you dont have the scanner. if you do adjust it to 12-14%

well...the jeep is gone...some girl pulled out in front of me on a back road and killed it...so fixing this issue just ceased to be a concern...unless i can find another that needs an engine for free or something...

thanks

Well, I have an 87, and I think I have the same problem. When ever I start up, the revs jump up to 2300 and then go down to normal idle, about 500-700 rpm. I'll have to check some of those causes mentioned above. If any one else has anything to say, it could help me out alot. Also, I have a screaming serpentine belt, it used to be only when it was cold, but now it screems just about every time you start it, what ever the temp is.