Originally Posted by richm
no, you're right, there IS evidently something forcing the iscv drive, or making the system think it needs a fast idle..
OR - as you say there is a fault.. I'm just trying to clarify the position with the TPS to avoid you chasing problems that aren't there unneccesarily.
Simon SECS is probably best placed to understand the conditions that would make the system think it needed a fast idle.
The other possibility is that the iscv drive output stage in the ECU is broken, forcing a permanent earth on pin 34 and driving the iscv on all the time - hard to know without looking at the signal with an oscilloscope to see if it's permanently low or switching (as it should be). Try briefly shorting pin34 to chassis with a length of wire whilst it's running and see if the idle raises even further - this would indicate if the valve is being driven hard on or only part on..
well as far as i was aware, when checking before, i plugged in the iscv, when it was removed from the engine and it just popped open, looked like full displacement.
in theory, if i put a voltmeter on it, as the car warms up the output voltage to it (measure the plug that goes on it) should drop as the valve is required to close????
this may give some suggestion?
will try fitting a new tps sensor, but dont see what this will achieve, as it will be set to the same voltage @ idle.
will try and skip off work early and get to the bottom of this tonight
will try all of the advice given here, and the help from simon@secs
