ENGINE REVS AT 4000 RPM AT START UP , DOES NOT CHANGE EVEN WHEN WARMED UP. FOUND THAT DICONNECTING THE IDLE CONTROL VALVE BRINGS THE REVS DOWN TO APPROX 800 RPM.
DOES THIS MEAN THE ECU IS AT FAULT ?
FROM WHAT I UNDERSTAND THE IDLE CONTROL VALVE WORKS BY PULSES ON THE NEGATIVE LINE FROM THE ECU. IF THIS IS JUST NEGATIVE, THE VALVE WOULD JUST OPEN AND NO CONTROL OF THE IDLE SPEED WOULD BE THE RESULT IS THIS CORRECT?