Thursday, April 18, 2013

Jaguar TPS X300/XJ6 Tips

The throttle position (Jaguar Part No. JLM12074) sensor (a potentiometer or variable resistor) sends information via voltage to various other components in the car. One key thing being how much gasoline to inject into the engine. A general side of a problem is increased rpm's, problems with O2 sensors and shifting issues. This sensor is easily damaged during cleaning of the throttle body by carburetor cleaner entering the unit.
Back of  original TPS

The correct output voltage is .6 volts. You will need a digital volt meter to check with. It is possible for a small amount of adjustment due to some play in the size of the bolt holes which can be carefully enlarged to allow more adjustment.
A small file or a drill bit might be used to make the holes oval/slotted. This unit can be replaced without removal of the throttle body from under the car.  It maybe necessary to remove the oil filter to have room.

It should be noted that a dirty or sticky throttle body or weal throttle spring can also effect incorrect idle speeds.

A possible replacement part that can be adopted for the 12cyl. with minimal work is Ford part number 90TF9B989 or AC Delco part number 213-848 for a 4-cly 1993 Ford Mustang. More details HERE.

Adapted Ford TPS
See also Standard Motor Products Part No. TH417.

To test it, you’ll need to hook your voltmeter up to the TPS without disconnecting the harness.

Have the ignition on, with the Throttle Pulley at the idle position.  The voltage should measure between 0.58 and 0.62VDC. If not, remove the Throttle Pulley and loosen the three small mounting screws holding the TPS and rotate the TPS until the voltage reading is within range.

Now, rotate the Throttle Pulley and watch your voltmeter – make sure the voltage increases smoothly – any drops would indicate a break or other problem in the TPS or a jumping reading indicates a dirty wiper arm inside the unit indicating it needs replacement.  Do this at least a few times.





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