Could a failed idle control valve prevent starting?

[navid41691]

That ^

For those who know i've been having starting issues, i checked out the icv because it was humming with the key in the acc position. Should I be able to see it spinning? because its not. Could this prevent the car from starting?

[monkeyodeath]

Pretty sure it's supposed to hum when the key is turned.

[jlevie]

The ICV should vibrate when the ignition is on. It is unlikely that a bad ICV would prevent the engine from starting.

[EThirty318i]

^x2 it would only cause an irratic idle when cold. take it off and shake it. If you hear something tapping inside it's good. as for your starting problem, what happens when you try to crank it?

[navid41691]

Yeah it does tap when I shake it. It just cranks and doesn't start. At first I thought it was the fuel pump so I changed it and still nothing. Checked all relays, fuses, even swapped out the dme.

[LJ851]

A bad icv can definitely cause a no start condition.

[nando]

The ICV should vibrate when the ignition is on. It is unlikely that a bad ICV would prevent the engine from starting.

it can, actually. Well, the engine would start, but it would die immediately. the ICV provides air for cranking, so other than what's already inside the cylinders the engine will be choked off if the ICV is stuck closed.

[nando]

^x2 it would only cause an irratic idle when cold. take it off and shake it. If you hear something tapping inside it's good. as for your starting problem, what happens when you try to crank it?

wrong. the valve can physically stop working. just because the solenoid moves when you shake it, doesn't mean the valve is working. you can check the resistance of the windings (I don't know the specs, but if it was bad the resistance would be very high or even very low), and see if it's humming with the ignition on.

[MaksV]

This is very easy to find out. Take it out and put 12V across it, there are 3 pins. the middle is ground I believe so as you apply 12V to the left then right pin it should open then close (or vis a vi) if it doesnt move quiuckly and easily, clean it out.


if it is stuck shut the car will generally start and die right away. But fi you put your foot on gas pedal, or hold TB open when starting itwill start fine.

[LJ851]

ICV's can be tricky to diagnose. Complete failure is easy to spot, but intermittent "failure" can happen. My experience was an intermittent no start when cold. The valve passed all the tests. The problem ended up being a tiny spot (as the valve rotates) where the circuit was open. By the time you touched the valve to test or remove it, it would have shifted and tested correctly.When the engine is hot it needs less air to idle and spends o lot of time there. When the engine tried to start after when cold, the icv would need to open more to allow the engine to start and idle but if it had landed on the dead spot the valve wouldn't move. It sounds simple writing this but was not easy to find!

Yes the car would start with application of throttle in that situation.

[nando]

yeah, I had one that worked half the time. at one point I had to physically smack it to get it to turn back on. I ended up replacing it with a new one.

[navid41691]

A bad icv can definitely cause a no start condition.

I really hope you're right despite what everyone else is saying because i can't think of what else it could be preventing my car from starting.

[nando]

try cracking open the throttle while cranking it over. if it still won't start, it's not your ICV.

[b*saint]

Nah, I unplugged mine, it started then didnt idle.

[EThirty318i]

okay, when i did my swap i ran into the same problem, put an adjustable wrench on the crank bolt, turn it just a little bit then try starting it. it might take a few tries. My starter was the problem... so i thought. the bendix was popping in and out like its suppose too but the gears weren't matching when it would engage and sat on the edge of the teeth. try that and let me know. Hope it helps!