98 JeepJeep

Finally got to drive my new (old) jeep (98) Cherokee 4.0.. When in gear the RPM stays at 1,200 RPM'S and when switched to N it hangs at 2k. I know I need to try to clean the IAC?? Do you just remove it and spray some gum cutter in it ?? my check engine light is on so im gonna have autozone pull the codes. Is there a write up for cleaning it? Any help/suggestions would be helpful.

SeriousOffroad

A thorough cleaning with carb and choke cleaner is easy to do. Pull the IAC (2 torx heads) and use a little scotchbrite on the pintle.

XJ Stryker

I would suggest adjusting the TPS also seems like it may be out of whack also.

okcjeeper

here's how you adjust the tps...looks like a real pain...

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

BlueXJ

Gentlemen the '98 does not have an adjustable TPS only Renix era Jeeps. I think that the TPS can be checked and replaced if found to be defective.

XJ Stryker

OOPs overlooked the year again I am so used to Renix.

So does this mean that if the HO TPS goes out you have to replace it you can't just adjust it. That sucks. hmmmmm Go to JY and pick up one and install it see if it fixes it. That would be a Cheap swap since JY onlly charge a few bucks for sensors rather than the 50+ auto parts stores charge for them.

98 JeepJeep

I will have autozone pull the codes..I know on my 88 mustang GT the TPS is NOT adjustabe and if the voltage reading with the key on engine off is out or range the TPS must be replaced. So is the link that okcjeep sent correct on the voltage reading and what wires to hook into to get the reading?? I dont understand why i would have to jump all 3 wires together to get a reading??? Now if i remove the IAC is there any gaskets that have to be replace?? or is it a straight forward removal.?

SeriousOffroad

Forget about the TPS untill you've cleaned the TB.

There is no way to adjust a TPS on an ODBII motor.

98 JeepJeep

The TB was cleaned when i had the intake off..the throttle will eventually come back down at idle when not in gear. So i think the IAC is dirty or faulty..i will try to remove and clean and post up the codes that i find.

SeriousOffroad

Have you tried pulling the codes using the key trick. ON-OFF 5 times, stopping on the 5th ON, and then watch the CEL and odometer.

okcjeeper

Hmm I didn't know you couldn't adjust the tps doh..I read that article at autozone's site and thought it was a bit odd you had to drill out the hole where the adjusting screw was...thanks for the correction...always good to learn new things..

BlueXJ

If you read the very first line of the operations it says the TPS is located inside the "Carburetor" which should give you a clue hat AZ doesn't know what the heck they are talking about.

98 JeepJeep

Advance auto let me use there scan tool and this is what i found

P0123
Tps/ pedal position sensor a Circuit high input
P0122
Tps/Pedal position A Circuit Low input.
P0700
Trans Control SYS Malfunction.

Now im going to replace my TPS with one in the JY and pull the battery cable and see if the CEL comes back. The TPS is the Sensor right across from the Firewall on the TB?? what years will fit my 98? What does the P0700 code mean?

BlueXJ

All 3 are related to the TPS so if you correct the first 2 the third will also go away.

98 JeepJeep

awesome!! i will try my best to get the correct TPS from the JY tommorow and hope that it to isnt FUBAR.