Discussion
Hi all,
Couple of 'technical' questions on the idle control valve if anyone has the knowledge please?
1. What position is the ICV in when disconnected, open or closed?
2. When running the engine with it in place but unplugged does the ECU know and would it compensate or switch to a 'safe' running map or setting?
3. What are the risks or possible effects of running and driving the car with it unplugged?
4. Does the ICV wear out over time? Should I expect to replace it?
Thanks, Andrew.
Couple of 'technical' questions on the idle control valve if anyone has the knowledge please?
1. What position is the ICV in when disconnected, open or closed?
2. When running the engine with it in place but unplugged does the ECU know and would it compensate or switch to a 'safe' running map or setting?
3. What are the risks or possible effects of running and driving the car with it unplugged?
4. Does the ICV wear out over time? Should I expect to replace it?
Thanks, Andrew.
AJC77 said:
1. What position is the ICV in when disconnected, open or closed?
2. When running the engine with it in place but unplugged does the ECU know and would it compensate or switch to a 'safe' running map or setting?
3. What are the risks or possible effects of running and driving the car with it unplugged?
Does the ICV wear out over time? Should I expect to replace it?
1. Open2. When running the engine with it in place but unplugged does the ECU know and would it compensate or switch to a 'safe' running map or setting?
3. What are the risks or possible effects of running and driving the car with it unplugged?
Does the ICV wear out over time? Should I expect to replace it?
2. Probably no, but I'm not sure about this one.
3. You may have problems starting the engine as there will be no extra air bypassing the throttle. The idle speed may vary a lot and the engine will probably stall when decelerating.
4. I suppose the solenoid can become faulty and the plunger could become blocked or clogged. If you have the "Hitachi" type, this can be disassembled and cleaned.
That's interesting!
Reason I ask the questions, just had both the tappets and timing checked and adjusted (tappets first then timing), as the final tweaks to the distributor angle were done (with the strobe light in hand) with the ICV unplugged and the engine fully up to temp the engine sounded smoother and sweeter than ever both at idle and when revved up.
Plugged the ICV back in and the engine immediately lost its smooth sweet idle and sound. The opinion was that it was then running weak fuel/air mixture wise...
Based on the ICV being mostly closed when unplugged I assume once plugged in it opened up and more air was introduced, hence the diagnosis of it going weak?
The thought now is whether enough fuel is flowing (dirty injectors)? Or whether the petentiometers in the MAFs need adjusting?
Funny thing is the car generally smells rich at idle and I usually stink of petrol and oil after a 30 min drive in it (says the wife)
It isn't running quite right that's for sure. Not badly but feels like it's missing a little power so something is out somewhere???
Reason I ask the questions, just had both the tappets and timing checked and adjusted (tappets first then timing), as the final tweaks to the distributor angle were done (with the strobe light in hand) with the ICV unplugged and the engine fully up to temp the engine sounded smoother and sweeter than ever both at idle and when revved up.
Plugged the ICV back in and the engine immediately lost its smooth sweet idle and sound. The opinion was that it was then running weak fuel/air mixture wise...
Based on the ICV being mostly closed when unplugged I assume once plugged in it opened up and more air was introduced, hence the diagnosis of it going weak?
The thought now is whether enough fuel is flowing (dirty injectors)? Or whether the petentiometers in the MAFs need adjusting?
Funny thing is the car generally smells rich at idle and I usually stink of petrol and oil after a 30 min drive in it (says the wife)
It isn't running quite right that's for sure. Not badly but feels like it's missing a little power so something is out somewhere???
You may find that the throttle butterflies are set slightly open at tickover when they should in fact be fully closed as all the tickover air should be supplied by the ISV.
I also read somewhere that if you disconnect the battery for half an hour, then reconnect and start the engine and allow it to idle till the fan comes on without touching the throttle, the ECU re-learns the correct fuelling. Seemed to work on my S3 anyway.
I also read somewhere that if you disconnect the battery for half an hour, then reconnect and start the engine and allow it to idle till the fan comes on without touching the throttle, the ECU re-learns the correct fuelling. Seemed to work on my S3 anyway.
Griffinr said:
I also read somewhere that if you disconnect the battery for half an hour, then reconnect and start the engine and allow it to idle till the fan comes on without touching the throttle, the ECU re-learns the correct fuelling.
Yes, I think you're supposed to do this whenever you change a sensor or ISCV etc, so the ECU can learn the calibration of the new part.Gassing Station | S Series | Top of Page | What's New | My Stuff