My 87 cherokee runs at very high RPMs like 4000 after 30 mph. Then i have floor it to 6500(red line) to go into overdrive(4th)....

Any ideas?

 

Check all your emission hoses, those will make it run at a higher rpm. It should be very noticeable bc you can hear a hose that came off.

 

Ok thanks i will check

 

adjust your kickdown cable
test your throttle position sensor for proper functionality

 

I adjusted the kickdown cable and it helped under 35mph. Still got other problem. Going to get multimeter today and check sensor tonight....thanks for the help

 

I've got the same issue with my 87, but I've got a manual so its slightly different.

To solve my issue I tap on my TB and it typically goes away. Leads me to believe my issue is TPS or IAC.

 

Put new TPS on and got a lot better response from motor. I am still having issue adjusting it. Do i probe the.back of the 4 prong with 3 wires coming out or the 3 prong conactor? Also what should i set meter to....like ac or dc or ohms to check output for adjustment?

 

I got it adjusted to 4.7 (a) white wire, 3.9 (b) blue wire. Overall .8297 v. Still need to drive it and see.

 

Tested jeep today.....ran at 5000 rpms about half the time the other times 3000-4000. I am thinking transmission. It will not shoft gears when it is supposed to. Going to change trans fluid and drive to see if that helps. Still looking for the answer to my problem stated before.....

 

Specs

87 cherokee 214000 miles
In line 6 motor
auto transmission

 

Idle shouldn't be bumped that high because of the trans.

Did you try anything with the IAC (idle air control valve)?

 

It idls at 1400 and no havenot messed IAC yet

 

I'd look there.

I mean, its called the IDLE air control valve.

Probably has something to do with idle.

 

I have kinda checked idle sensor by unplugging it and the engine raced. I pulled it out to inspecr no visable damage. There is a special tool to check it which i cant find the tool. Just waiting on the transmission selniods to come in the mail to fix shifting issue.

 

http://www.lunghd.com/Tech_Articles/...iagnostics.htm