Thread: Setting the TPS on a 3.9Efi

The 14CUX learns the idle point of the TPS as long as it is between

Throttle closed: 0.085-0.545 volts

This is from the test procedure in the manual for 1989 RRC eg same as all 14CUX.

It has to under 0.545V or the override injection cutoff will not activate.
Regards Philip A

Thanks Philip...but (and there's always a but)...the three RRC wires going into the TPS are different colour to those on my 1998 Discovery.
Yesterday I found a TPS with round holes...my current TPS holes are slotted which makes it adjustable?

Today I swapped it over and found the idle rough as ever so I swapped the old back again and all is fine.

The broken wire is right up against the body of the pot so soldering is impossible.

Thx.

The wires may be different colours but the functions are the same.
One wire will be 5V -it is the power from the ECU. One should be zero-it is the earth.
The third will vary with opening the throttle.This is the one you measure. I do it by sticking a pin in each wire for the pos multimeter probe and have the neg probe of the multimeter to the engine. if a purist you then seal the wire with a bit of liquid tape.

The Flapper TPS had slots as the idle had to be a certain value, and many people slot the later ones to set it to a midpoint value which I now forget, but you could do a search for. ( 0.27V?)

However I have checked several values as I have a "Heath Robinson " setup involving a nylon block adaptor, and a slot cut in my TPS to adapt it to my Thor manifold where I struggle to get to full throttle enrichment. So I tried all sorts of idle up to and over .545V and found the only difference was that the override injector cutoff did not work over .545V.
Regards Philip A