hi, i have a 98 jeep cherokee classic. it recently started acting up on me. at idle or while driving, the RPM's would drop off to below 1000rpms then shoot back up, then drop off, and so on and so forth and would continue that. i ran a scan on it, scan pulled up bad throttle position sensor, i just went and bought one. if anyone could please help guide me on how to correctly install it and make the adjustments to it i would greatly appreciate it. i love my jeep and its my ride to and from work so i would love to get it back up and in running order

 

No adjustments are necessary and the install in pretty straight forward. Just unplug the sensor, take out the two screws and it will come right off. What year is yours? The older renix motors tps's needs adjustment and the 91 and up doesn't.

 

ok. and once i do this, if it still runs the way it does, what do you think might be causing it? it called for an O2sensor, but i have been running without the 2nd O2sensor for like 2 months now and havent had any problems.

 

I agree, I don't think it would be the 02 sensor at all. From what you described, I'm betting it is the tps. If it still does it, report back but I bet the tps fixes your problem.

 

ok i will install new TPS tomorrow and if the problem persists i will let you know. thanks!

 

mine is a 98

 

No adjustment on yours. Plug and play. Install it and see if that resolves it.

 

Change the TPS - should resolve the idle issue.

If not remove and clean the IAC Motor or Valve, not sure what Jeep calls it.

Why did you remove the downstream O2 sensor? I don't think that is causing the problem you are referencing here but it might lead to other issues.

Check Engine light on?

 

What about the guys with the "brainy" renix 90 and down. how about the adjustment. not that mine needs it, but some day it will im sure

 

RENIX TPS ADJUSTMENT

Before attempting to adjust your TPS be sure the throttle body has been recently cleaned.
It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

IMPORTANT NOTE: Using one lead of your ohmmeter, probe the B terminal of the flat 3 wire connector
of the TPS . The letters are embossed on the connector itself.
Touch the other lead of your meter to the negative battery post.
If you see more than 1 ohm of resistance some modifications to the sensor ground harness will be
necessary. The harness repair must be performed before proceeding.
I can provide an instruction sheet for that if needed.

MANUAL TRANSMISSION:

RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C.

Wire "A" is positive.
Wire "B" is ground.

Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors..
Note the voltage reading--this is your REFERENCE voltage.

Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your
OUTPUT voltage.
Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For
example: 4.82 volts X .17=.82 volts. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.

AUTOMATIC TRANSMISSION:

RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a three-
wire connector, same as the manual transmission vehicles have, and it is tested the same as the
manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a four-wire connector clearly embossed with the letters
A,B,C, and D.. For the automatic transmission equipped vehicles the four-wire connector
provides data to the TCU.

Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your
REFERENCE voltage.

Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT
voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage.
For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage.
If you can't, replace the TPS and start over.

So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and
the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the three-wire connector side of
the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is
stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.

 

Hope it's ok to build on this post, I too have an issue with tps 1999 xj sport, 4.0 auto. I replaced the tps a month or so ago because of the same issue. The jeep ran great tell a week ago it got worse then I got code 1391 cam shaft position sensor or crank shaft position, being that mine does not have a cam shaft position sensor I replaced the crank shaft position sensor along with the pick up coil to be on the safe side. ( both genuine mopor parts ) now I still have a rough idle and still have code 122 tps. I replaced it again today and still rough idle, so I checked voltage at tps 5v, at idle 3.8v but.... When the throttle is opened the voltage drops to 1.2v please help I'm ripping my hair out!!!

 

You do have a cam sensor. It's in the distributor. It sounds like you are checking the tps voltage incorrectly. How are you testing the voltage.

 

Yes the pick up coil in the distributor (replaced) voltage meter back probed black to ground and red to throttle position 3.8v at start then slowly pressing the throttle its drops and ends at 1.2v once I let go it comes back up to 3.8v. Hot wire is at a constant 5v

 

Here's a method of checking a TPS.

 

That is how I tested it, hence the reason I'm so confused. According to the info above it says voltage must be less then 4.49v at wot mine is definitely less lol 1.2v which seems very low. Is that correct? If so what else would cause the miss I have and why do I constantly have a check engine light code 122 tps sensor?