I put a 92 engine into my 90 XJ. It currently will not shift gears without running the rpms up to around 5500. I did some research and found that the 3 wires I didn't use from the 90 throttle body go to the transmission control box.

Problem: the 92 intake only has a single tps sensor and not a double like the 90 had. Can I run both outputs off of the single TPS sensor? Is there an aftermarket TPS sensor I can use that would make it a dual TPS output?

Problem 2: My temp gage is showing it pegged to over heating when the engine is cold. I have tried changing the sensor itself. Does anybody have any other suggestions or things to try? It was working before the engine swap.

 

Well how much of the 92 engine did you use like was it just the short block or did you use everything from the 92.

Your 1990 came with renix fuel injection compared to the 92 which came with the chrysler fuel injection so i would imagine that alot of the sensor and connection are going to be different.

 

you should have used your 90 intake manifold to retain your renix system setup but have the HO engine.

 

5500? How has your 4.0 not blown up yet?

 

The head off of the 90 was bad and the 90 intake manifold will not bolt onto a 92 head (port openings vary). The bolt patterns are the same though.

I did find out that the 92 TPS sensor output goes to both the transmission control module and the engine control module. The 90 has 2 TPS sensors back to back and has one that goes from low voltage to high voltage and the other TPS goes from high voltage to low voltage.

Is it possible to swap out the transmission control module with a 91 or newer control module? I looked up inputs and outputs for the 93 (I have a schematic for that year) and they all look the same except for the 90 module having 2 extra wires for the TPS sensor.

Are their any differences in the transmissions from 90-93 electrical wise?

I have also rewired almost the entire engine to make the harness fit correctly.

 

I don't know exactly, but I'd assume that the transmission electronics stayed the same between years as far as wiring goes. they probably updated software or the TCU at least a couple times but everything else would make sense to stay the same. Just look in the wiring diagrams and compare, if they look the same go for the post 91 conversion.

 

I have no input for the first problem, but the second problem I have a suggestion. You said you changed your engine temp sensor right? If so, your gauge in your dash isnt connected to that sensor. It is connected to the temp SWITCH that is located near the (left or right, I cant remember which side) rear corner of the valve cover. I have a feeling that your 92 motor just has a jacked up temp switch.