Borgli

Hi, I am having trouble with high idle. It happens at random times, sometimes it goes up to 2500 for 5 seconds. Other times it goes up to 3000 - 3200 and can stay there for 10 minutes, which makes driving stupidly dangerous as it goes up to almost 30 mph without touching the gas pedal. Sometimes I can fix it by stepping on the gas really hard a couple of times. Other times nothing helps. I cleaned the entire throttle body area a few months ago. This issue started about two weeks ago.
What is causing this?

cruiser54

Did you remove and clean the IAC at the same time?

bryant01

un plug the idel sencer and c wat it dose

Kalali

luv yur inglish language skeels. Yu must b an inglish major....harvard or yale?

Borgli

Do i unplug it, then start and see what the thing does? Wont that cause it to rev like crazy?

cruiser54

That's a hokey test. Did you clean the IAC when you cleaned the throttle body? Did you remove the TB? If so, did you replace the mounting gasket?

VTJeep

There's a way to adjust the TPS on these right?
Idk if this helps..

cruiser54

Here's the proper way to test. Remember: flat connector for driveability like you've got, and square connector for trans problems.


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: With the Key OFF, and using the positive (red) 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 black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, 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 flat 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 square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. 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.
FOR AUTOMATIC TRANSMISSION RELATED 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.
Revised 08-27-2012

Borgli

I did remove and clean tne iAC, I did not remove the throttle body. I will remove it this saturday and clean it out good. If that doesn't work I'll get my hands on a voltmeter and test the tps.

Is there a trick to getting the throttle cable off the throttle body?

NorCalJeep

just unplug it. Don't get the chinese TPS(if you need to replace), my brother got one and it still runs like ****.

cruiser54

Really not necessary to remove the throttle body. I was more concerned whether the IAC had been cleaned.


Spend the time checking the TPS at the flat connector per my instructions.

Borgli

OK, so I haven't had the time to check out the connections yet. But I discovered something the other night;
I got out to start the car, it revved up to 2250 rpm so I shut it off. Then I shifted through all the gears with the key in the on position before starting up again, this seemed to cure it. (usually I have to start and shut it of 3-4 times before it calms down.) Haven't had any problems since, I have been shifting through the gears every now and then just to be sure it wont rev again.

Anyways, just thought I'd put it up here.