Okay so an update I've sprayed all along the intake and the lines with carb cleaner and nothing changed with the revs at all so I unplugged the idle control valve sensor and the engine then started running normally with the idle revs steady so I then plugged it back In to find that the car then carried on running normal. Does that mean the idle control valve is faulty or the fault is after that? I've already changed the idle control valve admittedly it was a ebay part I brought but I have tried 2 being as the seller offered to send me a other free of charge.

Thanks for your thoughts

Edited by Ryan Clements on 18/09/2021 at 18:34

Remove the idle speed stepper motor but don't unplug it. Using brake or carburettor cleaner spray into the manifold to clean the seat, and onto the valve making sure you remove all the carbon. Use a cloth to wipe it clean too. Then lightly hold the stepper motor between your finger and thumb to prevent the valve coming all the way out, switch the ignition on and then off. The motor will turn and find its correct position. Make sure you allow it to move, but don't allow it to come apart. Switch the ignition on and off a couple of times, waiting a few seconds between each operation. Then refit the stepper motor making sure the O ring is properly seated. Switch the ignition on and then off. Finally start the engine. Hopefully now the correct idle position is found and the engine should idle as it should.

Hi Railroad when you say hold it between your finger and thumb do you mean the spring side and the back?

Yes, that. When you switch the ignition on and off the plunger will move in and out. The ECM counts its steps between 1 and 255. The motor will turn until the correct position is reached. Once this position is correctly established switch off the ignition and wait a couple of seconds for the motor to set itself for the start position and then re-fit the stepper motor. Sounds complicated to explain, but it I could demonstrate it to you you'll see it's very straightforward and easy.

Okay I'll give it a go I wasn't sure it would start with the stepper motor out though it might just die but I guess not because I can unplug it and it sorts it's self out. I'll given it a go thanks RailRoad

Don't start the engine with the stepper motor removed. Just switch the ignition on and off.

There shouldn't be any clicks. By the sounds of it you've allowed the plunger to come out of the body. Switch off the ignition and push it back in so it does click a few times. Then switch on the ignition whilst preventing the plunger coming right out. Then switch off the ignition and wait a couple of seconds. It should move to find its position. When it has refit the stepper motor.

Okay so an update folowing on from Rail roads Advice I haven't noticed any difference in the idle however I have tried a few things and noticed that if I rev the car to around 2k revs and then let go of the throttle the revs drop right down to around 500 almost stalling before going back to around 900 and then the surging happens. I've also noticed no matter what revs you get the engine up to if you hold the throttle at the point you can hear a slight bump kind of noise and the engine seems to bring the revs slightly down before going back up again I don't notice this driving however I'm not sure I would. it's almost like a misfire every 5 seconds when the throttle is down a bit... not sure if this could maybe bring some new advice? I've changed the spark plugs recently. And checked the exhaust for leaks

thanks again

Ryan

Once again it's raining here! Haha so no chance of checking any voltage just yet but could not be the sensor itself or the wiring?