m42 ICV too quiet?

[Boris3]

So the ICV in my 325i has an audible hum/vibration when you turn the key, but the ICV in the 318is is so quiet the only way I can hear it is with a stethoscope and even then just barely. Is the m42 ICV supposed to be so quiet?

The ICV ohms out correctly and I've cleaned it but no change, still quiet. Could be two different things but I've got a slight stumble at idle and I'm wondering if the ICV might be part of the issue.

[kwill22]

I've had an ICV test fine and not work correctly though. Usually the ICV sticks when it's bad so if you tap it with a wrench or something while you're cars runnin it'll return to normal. Checked for vacuum leaks?

[Boris3]

Took it off, cleaned and shook it. No change if I tap it. The quietness just makes me wonder esp since the 325i has a really noticeable hum.

Idle symptoms are just the slight stumble. When the ICV went on the 325i it was more of wide swings in the idle. Not on the 318is though.

Vacuum leak check? No smoke test or carb cleaner spraying yet. I've replaced all hoses since they were shot anyway. oil filter housing since it was leaking. Could be intake manifold gaskets.

[kwill22]

My ICV is quiet also but I know I need a new one. When I start it sticks open. Idles about 1500. Then once I've hit second gear it'll start to work normally whenever I idle after that. It's annoying but I don't feel like spending the 150+ for a new one. Lol

[Boris3]

Funny that the 2nd gear hit gets you back to normal. Warms up enough to loosen the buildup?

My idle stays around 850 but with slight dips when it stumbles. So I guess it's working but the fact that it's quiet is still a puzzle. Saw a thread somewhere that said the Bosch ICVs hum but the VDO are quiet?

[Delta]

When my ICV on my M42 was going bad I got wide rpm fluctuations, 500-2000 or so. Replaced it with a new bosch unit and it works great.

You are right though, they are very quiet on the 4 cyl for some reason.

Mine doesn't idle perfect either but I don't think you'll find an m42 that does. My tach doesn't flutter really but you can feel it in the seat. Also, when stopping after deceleration my idle sometimes dips and then goes back up to normal. I've learned to just accept it and move on.

[///M42 sport]

My idle is pretty steady

[Delta]

My idle is pretty steady

Yeah? Mines not bad but it's not inline six smooth either.

[ck_taft325is]

Mine's ridiculously steady. Dead steady.

Then randomly the engine will stutter and start to cough and try and die. It's amazing. Like watching a train wreck in progress. Throttle keeps it barely alive but it's almost like there's not enough to keep it moving. Then, it straightens out and it's fine. Go figure, 'eh?

[roguetoaster]

Then, it straightens out and it's fine. Go figure, 'eh?

Sounds like the M42 mantra.

[DER E30]

Mine's ridiculously steady. Dead steady.

Then randomly the engine will stutter and start to cough and try and die. It's amazing. Like watching a train wreck in progress. Throttle keeps it barely alive but it's almost like there's not enough to keep it moving. Then, it straightens out and it's fine. Go figure, 'eh?

This describes mine also
Runs much better when warm than cold...

[DER E30]

I should also mention that I'm pretty sure my FPR wasn't hooked up from the last time I had the intake off and it runs much better now