Need Help...Very high idle (Have searched)

[tda88]

So...I was driving home the other day and overheated the 'manche pretty good. I fixed the problem with the cooling system...but now I have an extremely high idle like 2,500-3,000 rpm. It is very intermittent it started only when it was cold then idled at about 2,500 for about 3 mins, then would kick down to normal. Now...it's fine when cold and seems to only rev when warm, but after I turn the engine off, let it sit, then fire it back up again it now revs at 3,000 (very annoying) and takes like 10 mins to kick down. After doing some searching and talking to other jeep buddies I think it is the TPS (throttle positioning sensor). My real question is... do I really need a volt meter to correctly adjust this thing? Can I do it without one? anything will be better than 3,000 rpm right? and...when I unplug the TPS the idle goes to pretty much where it needs to be. Can I just leave the thing unplugged? Anyone with any personal experience? Any long term issues with just leaving it unplugged? I picked up a TPS at my local junk yard its the exact same unit can I easily pull mine out and plug the "new" one in and try it or am I in for a big adjustment nightmare without a voltage tester? Any help would be greatly appreciated. I've read all about the adjustment in other posts I just do not have a tester or money to buy one right now. Pretty much wondering if it's doable by hand?

[1987Comanche]

I adjusted my TPS with a multimeter (I'm assuming you have the Renix 4.0) and I think that, in a pinch, you could set it without one. If you loosen the upper and lower adjuster screws, then start the truck, you should be able to twist the TPS left or right and see what effect it has on idle. Once you get it in the ballpark, shut the truck off, tighten the screws down and see how close you are. And definitely watch the serpentine belt when you are twisting the thing!!!!

[kyleag89]

You can try it by hand but I really don't think it will be right.. I would try borrowing a voltmeter/multi-meter from someone. Idk about everyone else but my TPS has to be perfect or my truck runs like crap and idles high.

[tda88]

Thank you guys for the quick responses...I have a long trip ahead of me and I need the truck dependable. What about leaving it disconected? anyone have any thoughts on that. And...yes, it is the original '87 4.0 in it the Renix

[Geonovast]

Clean the IAC before you start screwing with the TPS.

[tda88]

Is the IAC the one to the left of the TPS?

[kyleag89]

Yes, clean inside the throttle body where the IAC goes into also.

 

Look at this site it will show you all the sensors and explain what they do..

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

[tda88]

will do, thank you...i have been really reluctant to remove the TPS just baised on what i've read (sounds like it can turn into a big headache) I will do all of that first! good advise

[cluricaunne]

you may want to try swapping out your MAP sensor also, located on the firewall, to the left of the clutch master cylinder... helped mine out quite a bit.