Very high idle on 90 jeep cherokee?

Question

As some of you may know I recently picked up a beat up old jeep cherokee.The night I bought it it hesitated to start but I figured it was just because it sat for so long.I got it home went in had a sandwich went back outside to go to my brothers place and the mother$%^#@$% thing was DEAD.I snapped lol.Finally I realized no juice left,so I boosted it and it started right up.Now the $#%@ starts .Suddenly it's revving at 1400 in park,but when I shift into drive it drops to 1000.I've read thats the cherokee with the inline 6 is supposed to idle at about 600 to 650.Is that true ?What could be the problem ?I do have quite a bit of mechanical ability and access to a wrecking yard in the family?

As big a piece of crap it is I still love it lol.

1 more sorry.Where should my battery guage and oil guage at?

Answer 1

Hi Gerry,
You asked me in another post about your ABS. If the previous owner did not remove anything when he disconnected the system and you do not have anything wrong with the wheel sensors, the ABS master cylinder and pump,,under the overflow bottle.( Kind of an over flow) is under warranty FOREVER! The ABS computer is under the back seat, drivers side. Good Luck on this.
Hi idle, some other answers are good. I have also had this show up. Yes vacuum leak at intake or throttle body could do this. You said that the ABS was disconnected, how do you have power brakes? If a vacuum booster was added, it could be leaking. You did not have Vacuum assist with this Bendix ABS system.
No leaks..ok, I had several problems with the stepping motor sticking and it will cause this. One person said "Hook to a scanner"..obviously never been around a pre 1991 Cherokee. No connection. You need to find a manual to check the throttle position sensor with a DIGITAL volt ohm meter. You check the voltage across two of the wires and subtract to get a value. Don't remember exact right now, but the manual will go into it.Son has the manual off at school. Note, the throttle position sensor also controls your transmission.
My vote, the idle stepping motor is the problem. You can clean it, but I would not disassemble it.
Good Luck

Answer 2

test don't guess first inspect computer ground [right side of engine rear of distributor on cyl head [over the years i have found more than just a few broken or loose]
next have alternator output checked and battery load tested and be sure the alternator diodes are doing their job [no stray alternating current getting into your direct current system] remedy as needed.[renault/bendix jeeps were very susceptible to this]
next clean out the throttle body and air bypass passage with carb cleaner and a brass "toothbrush" then using a scan tool, test the throttle position sensor. adjust or replace as required.
scan tools that work on this model are MS 1700 [factory tool] drb 2 up and all snap on scanners from the brick up [this system uses a live data stream without long term storage], if you cut the key off the computer resets until another "event" happens. so watch for "fixed" values and implausable readings. the diagnostic connectors are under the two yellow plastic covers on the right inner fender midway up these same connectors were used on all jeep and renault models from 1983 up [except grand wagoneer and J trucks with V8 engines] on both fuel feed back systems and fuel injected systems such as yours and yes the fuel feed back systems can be read with a scanner too.

Answer 3

Replace the head gasket now!!!!!!! before you kill the engine. Is the fan working ? The more work you ask the engine to do the more heat it makes. That leaky head gasket may be leaking compression into the cooling system. Open cooling system ??? you mean you have no overflow tank?.Does the performance rad have enough capacity, the correct flow ? is it designed for a cherokee? I've seen trick aluminum rads that didn't cool worth a damn. Make sure the electric fan is coming on .

Answer 4

Not much here. '90 I will guess is injected. If so the fact of sitting may have messed up the throttle position sensor (tps) located on the throttle body. If the throttle plate does not close to idle it will tell the computer there is a lot of air entering and the computer will give it too much fuel. thus high revs. A bit of cleaning might solve your @$#%&* problem.

Answer 5

this website might have some answers for your problem.
http://autorepair.about.com/library/faqs/bl051i.htm
one more thing if these dont work and you have a service manual for your ride look at the throttle valve linkage adjuster
in the tranny section of your manual. my father in law said his jeep did the same thing and that fixed his problem.

Answer 6

You might also check the idle control valve on your throttle body, it could be stuck.

Answer 7

such language ! : ) check for a vaccum leak or weird stuff in the egr or pcv systems . good luck .