E30 Zone

Is there a way to test the ICV opens and closes? I have soaked it in carb cleaner but idle is still lumpy.

I seem to recall the signal to the ICV is just 12v PWM (i.e. rapidly switched on and off), and with mine I just applied a constant 12v to check it worked. When doing so I think it would slam open with a bit of vigour, it's not something you could miss. You can also use your finger/screwdriver to manually move it and check for smoothness.

All that said, I bet the lumpy idle is something else. I forget if you changed all the vacuum hoses with your engine swap, but might be worth checking again. Mine had a leak on the pipe to the brake booster which seems to get overlooked by most on a leak hunt.

'Lumpy' idle is nothing to do with the ICV, unless it was simply not opened enough, and the idle was at far to low RPM. All the ICV does (in conjunction with the ECU) is set the RPM for the idle.

TheDutch wrote:I seem to recall the signal to the ICV is just 12v PWM (i.e. rapidly switched on and off), and with mine I just applied a constant 12v to check it worked. When doing so I think it would slam open with a bit of vigour, it's not something you could miss. You can also use your finger/screwdriver to manually move it and check for smoothness.

I have tried moving it with a screwdriver but it seems fixed.

It should definitely move with a screwdriver levered correctly, I can do it with with my finger easily enough. Previously I've popped it in the opening that appears closed and rotate it, albeit less than 1cm of movement.

Failing that I'd try powering it up.

I would ONLY try powering it up (with a 6 volt battery). Keep the screwdriver out of it; these things are fragile.

They are somewhat delicate but I think a screwdriver is fine if used appropriately, just don't be ham-fisted about it. As mentioned, I found it easy to move with a finger, it doesn't take huge force.

Also seem to recall it's pretty normal to test them by briefly applying 12v, just don't leave it on continuously.

Suddenly applying 12 volts is going to slam it hard against its stop, which can't be good for it.
A variable supply, increasing slowly from zero is ideal, since the main thing that goes wrong with them is that they stick at one point, but a 6 volt battery will prove that it works, without the violence of 12 volts.

This is what it looks like



I have tried gently moving the rotating part but it is stuck, I haven't connected a battery to it yet.