I did a search with no results, so maybe someone can help me. I bought this 93 XJS 4.0 last fall, it had been sitting for several years and had a new head gasket installed before the PO stored it. He never really adjusted anything after the head gasket install and had moved or removed just about every electrical sensor. Anyways, it ran very poorly after I trailered it home, but the brakes were my first big undertaking. T
The brakes are now, all new and the car is drivable. By ear and trial and error, I was able to get it to run fairly well, but at idle it searches and misses. I've gotten it smoothed out somewhat by cleaning the intake and air bypass meter and adjusting the air bypass adjuster and the adjustment on the MAF, but it still is not right, I've been reading up on the TPS adjustments (since the PO removed it for some reason) and I think if I can set the TPS correctly the idle will be corrected. I already checked the the temp sensor with a meter and it is within specs, I removed and cleaned the air bypass and throttle body. I also installed a highflow air filter. It ran terrible with the original air filter on, so I don't think that is the problem.
What I really need is a, as detailed as possible description of how to set the TPS with a Volm meter. I've read that the reading should be 0.6 volts in closed position, but I have no idea of how to take this reading. I found the connection, but I don't know which wires to check, how to check them for volts when the plug is disconnected etc.
If anyone can direct me to a site that will describe this procedure in a step by step fashion (hopefully with pictures) I would love it or if anyone would be willing to write a description for me, I would greatly appreciate it. Help
93greenconv

 

I really have no idea about the 4.0L cars...

Here is a pictorial of how to adjust it on the V12s... not sure if your's is common. To test the voltage across the wires (red and yellow in this case) push a sewing needle into each wire and measure the voltage across them with the ignition on.

Throttle Position Sensor Testing

Cheers,

- Will

 

Thanks for the post, I've been able to figure out how to test the TPS, but I can not determine which color wires to use to test it. I have the rectangle plug and the wire colors appear to not be the same as the round plug.
Does anyone know which two wires I should use to test the TPS on a rectangle plug for a 4.0 engine.