Revving Problem

I own a 98 Freelander and roughly 3 months ago its started to over rev in idle up to 2000rpm. The amber HDC light also came on and stayed on.
I replaced the plastic throttle body with an ali version but this did not cure the problem. No faults where found when it was hooked up. Therefore i decided to replace the ECU whilst waiting for this to be delivered i dis-connected the potentiometer, When it was re-connected the idle problem was no longer there and the HDC light was off. i took the decision not to replace the ECU........... Guesss what the problem came back yesterday


Any Suggestions

You need to set the base idle setting with the screw on the throttle body, you need T4 to do this as this reads the stepper position and you turn the screw to the right setting according to the stepper position. If the setting is wrong then the idle air control goes up the swanny giving you the problem you have.

HDC light coming on on 1.8's is normally down to throttle cable adjustment, there is a hall effect sensor on the throttle pedal and the throttle position sensor, if the ECU detects the throttle opening before the hall sensor says the pedal is being pressed (cable too tight) then the ABS ecu thinks the throttle is stuck therefore putting the light on and logging a "throttle stuck error" fault. (ABS and engine ECU talk to eack other on the CAN)

Adjust the throttle cable so there is about 1/2 to 1 inch movement on the pedal before the throttle opens.