Weak Idle Control Valve

[bmtrblu]

One more existing problem, now that I have the last one fixed. My ICV seems very weak. I have changed it out, and both are very slow to respond. Both are squeaky clean, move freely with the touch of a finger. I am wondering if the signal itself is weak. Any ideas?

[Brianmoooore]

WHAT CAR! What, exactly, is the problem you are having that makes you think the idle signal is 'weak'?

[bmtrblu]

Problem started about two months before the DME breakdown. Acceleration lags at cold startup. If you remove the ICV from the intake and turn the key, the valve is very slow to close. I thought initially the ICV was bad. Bought refurbished, same response. I also had one here for some unknown reason, and it to responds the same. Also, it is very quiet. It used to be I could hear it as soon as I turned the key to on. Now, nothing, I can feel it has a "vibration" to it, but not like before.

This is an 1988 325i Convertible.

[jimbom30cab]

It should buzz quite obviously when the ignition is on so that sounds odd.

It might be worth checking for voltage at the connector, middle pin 2 should have 12v to ground and the other 2 should have 10v potential difference to the middle pin.

The middle pin is a direct 12v supply

The outer pins are a feedback loop from the ECU in some sort of balanced bridge set up and there is not much you can do to adjust the voltage i believe

Worth checking the pins on the ECU that the voltage is the same as the connector also - i think it is pins 4 and 22

If the voltage is not right then something in the ECU is bad or a bad signal into the ECU

Limit of my knowledge i'm afriad but hope it helps

[bmtrblu]

Cool, thanks. That's more than I knew...