Ok folks replaced the 2 relays for Transmission located over pass.rear wheel arch and still have limp home mode appear............what is further up the food-chain I should check next..............The transmission is in good working order, it I turn the car off then start again the limp home mode goes away and stays off...........the one replay would get hot but a replacement from Welsh Ent. did not fix the issue

Steve Q

1994 XJS 4.0 engine convertible 2+2

 

4.0 straight six, so drill two small holes on the bottom of your TPS and insert the straw end of an electronic cleaner can, and spray. Crud will come out the other hole. The crud that is tripping your TPS, is what is causing it to go into limp mode. The two drilled holes should allow oil that leaks inside to drip out, instead of pooling. Ive had this happen with every 4.0L that Ive owned. Once drilled it wont happen again.

 

Interesting...the TPS is mounted inverted on the throttle body, correct? How does oil get in? Just vapor oil that drips down into the TPS from the TB throat?

 

Its the location which allows oil to seep in and pool inside. Drilling holes has been a trick I learned from owning XJ40s. Bunch of good info documented there, since the majority of the cars were inline 6. V12s are well documented here as well.

 

Check the voltage on the throttle potentiometer. This should be 0.6V when the throttle is closed.
Incorrect information for your car

Opps. Do you have AJ16?

 

Its a 1994 so its an AJ6. I have the same year car. Cleaning the TPS is easy.