95 Range Rover

[dukemanpilot]

Please, can anybody give me any idea of what is happening to my vehicle? Original owner, 60,000 miles on it. Basically when I'm out driving on a paved road at 35 MPH, the RPM needle starts bouncing down and up, down and up and the vehicle jerks with every dive of the needle. If I step on the accelerator the gear drops down and I have plenty of power but as soon as I get settled back to the 35 MPH range it starts learching again. RR service and my own mechanic can not seem to diagnose the problem. Anybody else run into this problem?

 

[joey]

First, what kind of service has been done to the vehicle?

Plugs, wires, distributor cap, fuel filter....

I would say the VSS is going bad, but would like more info first.

 

[dukemanpilot]

Fuel filter was changed, old one looked good. Plugs changed, injectors cleaned, pick-up coil checked. Fuel pump is functioning properly. What is the VSS?

 

[joey]

Vehicle speed sensor
The vehicle speed sensor is located on the side of the
Transfer box adjacent to the parking brake. The
sensor provides road speed data to the ECM. The
ECM in turn detects vehicle movement from the road
speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in
service the ECM idle air control would become erratic.
The sensor also provides road speed data to the
electric speedometer and cruise control ECU.

 

[dukemanpilot]

All Fixed! Throttle position sensor!