Sidewinder69

This is my first post here and I would like some help Please. I have an 89 XJ Wagoneer 4.0 With the AW4 transmission. The problem I am having is, I will be driving and at different times and speeds the RPMs will increase as if the transmission is slipping. It mostly happens on the highway around 55 MPH and the RPMs will go from 2000 to 3000. I will let off the gas and repress the pedal and the RPMs return to normal. When it does this I do not loose any speed it just seems like the transmission goes into a lower gear. Has anyone had similar issues or can somebody direct me in the right direction.

Thanks

freegdr

search adjusting the kick down cable would be the first thing to check

tjwalker

1. How many miles on this transmission?

2. What is the history of routine fluid changes on this transmission?

3. What is the level of fluid on the dipstick with a hot engine?

4. What is the color of the fluid? (red is good)

5. Does the fluid smell burnt? (NOT GOOD if it does)

6. Adjusting kickdown cable is never a bad idea@

7. As well as testing AND adjusting your throttle position sensor@ The TPS is directly involved with transmission shifting characteristics

Sidewinder69

1. How many miles on this transmission?

277,000

2. What is the history of routine fluid changes on this transmission?

I am not sure as I have only had the Jeep for about a year. I want to do a filter/fluid change but I am afraid it will do more harm than good. I have heard on high mileage transmissions if you put in new fluid it might cause the transmission to fail.

3. What is the level of fluid on the dipstick with a hot engine?

Full


4. What is the color of the fluid? (red is good)

Red

5. Does the fluid smell burnt? (NOT GOOD if it does)

No

6. Adjusting kickdown cable is never a bad idea@

I will attempt to adjust, I have not done one before

7. As well as testing AND adjusting your throttle position sensor@ The TPS is directly involved with transmission shifting characteristics

I will try that because at times my idle will jump up and will be at 2000-2500 RPMs and will not kick down. I have to shut the Jeep off for a minute or two then it is fine once I restart.

tjwalker

277k is plenty of miles. If this is the original tranny, it might be on its way out.

That being said, new fluid is worth a try. You have absolutely nothing to lose here, do you? The myth of new fluid hurting an old transmission is exactly that. A myth. You may not want at power flush and fill, but gently replacing fluid is ALWAYS better than leaving old fluid in the tranny.

Drop the fluid in the pan and replace with the 3-4 quarts it takes to refill. See if that helps.

And test and adjust that TPS!

Simple stuff first before you start shopping for a salvage yard tranny for your XJ!


RENIX TPS
(Thanks to Joe Peters from NAXJA for this information)

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. Wire "A" is positive. Wire "D" is ground. Remove the three-wire connector from the TPS. Key ON, measure voltage from "A" positive to "D" ground. Note the voltage reading--this is your REFERENCE voltage. Now, reconnect the three-wire connector to the TPS. Key ON, back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. 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. For the automatic transmission equipped vehicles the four-wire connector provides data to the TCU. Disconnect the four-wire connector. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Now, reconnect the four-wire connector to the TPS. 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. 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.

tjwalker

double post. Sorry. Computer eligible for the Smithsonian!

Sidewinder69

Adjusted the Kick down and so far after 20 miles to work it shifted fine.

Thanks for the input