Rover SD1 Efi Archive - Throttle Potentiometer

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Here is a definitive description of the Rover SD1 Efi throttle potentiometer. Of all the components in the Rover SD1 Efi system this is the one that will certainly fail within the lifetime of the car.

Indeed its normal lifespan is only 60K to 80K miles and because original spares are no longer available, their failure causes considerable grief in the Rover SD1 Efi community and during the past few years a number of "Owner DIY Solutions" have been developed.

One of the answers even spawned a cottage industry which briefly provided substitute units.

There have been many questions asked and answered in magazines, web sites and forums about this problem and because there is general confusion regarding its use, purpose, failure mode, repair and substitution I have covered all those subjects in this definitive explanation.

Briefly, the Rover SD1 Efi throttle potentiometer is connected to the spindle of the throttle butterfly. Its purpose is to advise the ECU of the driver's accelerator pedal position and its rate of change.

When the throttle is operated, the potentiometer rotates to vary a voltage and send an appropriate signal to the ECU. In this way throttle movement is sensed.

The ECU detects the rate of change of the voltage across the potentiometer connections and when appropriate, triggers the acceleration enrichment circuits.

Also, at full throttle the ECU detects a maximum voltage signal to provide full load fuel enrichment.

Now read or download the whole nine page document in PDF format here (294kb)

Please advise of errors and omissions.

More Efi Components here

Description and Purpose

Adjustment

Testing

System Response

Repair

Conclusions

Substitution - Implications and Fitting