Hey lately my trannys been actin weird. If I'm going down the freeway and hit a bump or uneven lanes itll down shift and shift right back. But then when the slightest lift off of the gas pedal will make it downshift. I have to come to a complete stop for it to like " reset" it so it'll work properly. Could it be the s1 solenoid? Tps? Thanks guys

 

1990 xj, 4.0 automatic l6

 

i was just going to make a thread about this! happened to me today too.

 

im getting the exact same problem with my 96 and its getting so bad that the tranny is burning the oil in atleast a week its verry annoying i kick it into neutral and just restart the car while its rolloing down the road and that does fix it for a while

 

This might not help too much....I just did some stuff with my TCU wiring. While I had the panel off I realized I was lucky that I hadn't run a screw into the TCU mounting a cup holder years ago. It's right behind the panel below the glove compartment. Also, if jostling causes it I might check the wires down under....

 

Job #1 for erratic shifting performance for the 87-90 is listed below. Try it. Note: This is for 87-90, 91-01 TPS is different and is non-adjustable, although it can be TESTED.
---------------------------

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.

 

Thanks the advice, tomorrow I'll have try that and see if the tps Is bad.
And for the other people having this problem, I found if you drive with the tranny on " power " instead of comfort it doesn't do it as much. I don't know if the comfort switch is bad?