The V8 Owners Forum -

I've noticed that when I turn on the ignition, the stepper motor activates / sets itself up as normal but there is a high pitched wine sounding like a typical electrical component wine. It is constant and only stops when the ignition is off (obviously). Is this normal?

Seems it is normal. Surprised but fine if it is normal.

I am no expert but surely there should be nothing once the car is warmed up, maybe its trying to "step" but is against a hard stop ie fully closed, you could try changing the settings in MS, or do a test to see where it actually shuts off the airflow and then re-enter values in the MS.

Needs someone with a whole load more knowledge than me to confirm though

richardpope50 wrote:I've noticed that when I turn on the ignition, the stepper motor activates / sets itself up as normal but there is a high pitched wine sounding like a typical electrical component wine. It is constant and only stops when the ignition is off (obviously). Is this normal?

A whine suggests something spinning quite fast? Stepper motors tend to move quite slowly (in electric motor terms) and once they reach the end of their travel stop. Unless reversed. Even if you sent a series of forward and reverse commands to one I'd not expect it to whine. No chance it's the fuel pump? Probably a silly question.

It's definitely a high pitched wine from the stepper and sounds just like a wine one gets from electronic circuits / components (probably in the olden days). The stepper motor seems to work fine and whirs whilst it opens / closes and then stops as it should (on ignition on).

There are two setting in megasquirt for a 4 wire IAC valve; moving only or always on. You can leave it to always on as long as the valve doesn't get hot when powered up on a bench test. My valve is set to always on and it doesn't get hot and works fine. Did have a problem with my wiring, would only move one way but that was just two of the wires were the wrong way around.

Would you call the noise yours makes a hum?
Does the valve get hot? (obviously not when the engine is hot)

Tom.

Does it whine when the engine is off/ ignition on or engine running?

Could it be an air leak? Obviously wouldn't make a noise when the engine is off!

Tom.

Tom,

Did a test last night ...

No, it does not get hot.
It's a very high pitched wine / whistle and definitely not a hum.
Interestingly, if try and pinch it with my fingers it reduces to almost nil in a certain position. I'm not sure if this is because my fingers are absorbing the sound or not.
It's not loose at all.
I tried undoing the stepper a bit but that made no difference.

Still none the wiser!

Ah, that's the sound of the air rushing through the valve.

When the engine is up to operating temps the valve should be shut - so no noise - are you sure the valve is closing completely? Either MS isn't telling the valve to fully shut or it can't because it's gunked up/seized. (DON'T try and turn the pintle with pliers... Don't ask me how I know! You'll break the valve) You should be able to push the valve in by hand when the ignition is off.

There is a setting in MS when powering on the ignition the IAC valve moves out a certain number of steps to find where zero/closed is then moves back to cranking position. Maybe you don't have a large enough number of steps to fully close and re-set the valve?

Does the valve fully extend? try taking out out and putting it in a bag to contain the bits! Turn ignition on and the valve should move out and the pintle + spring should pop of into the bag - can be re-assembled. Did mine with out a bag and had to search the garage for the spring and pintle!

Tom.

Surely MS will control the actual idle speed, so the valve may not be fully closed under all conditions?

Can do but depends on the settings you have selected, either warmup or closed loop.

Warmup slowly closed up to a temp where it should be fully closed.
Closed loop will try to adjust to a maintain a defined idle speed, although I think it is more geared towards helping maintain your idle speed when something like the aircon kicks in rather than saving your engine from stalling by using the wrong gear!

Tom.

Tom,

Ah, that's the sound of the air rushing through the valve.
>But engine is not running. Just ignition on.

When the engine is up to operating temps ....
>All seems fine. Whole lot cleaned some time ago and open / close all seems fine. I followed some cleaning instructions to the letter.

There is a setting in MS when powering on the ignition the IAC valve ...
>Yep, all seems fine.

Does the valve fully extend?
>Yes.

The engine starts then within a few (less than about 5) seconds drops back from about 1,500 to a nice 900 rpm idle. It all seems to work fine.