YOUR M44 Idle Control Valve
 

Just wanted to contribute my 0.02 about the M44 ICV.

My car was laid up for a while, and while the intake tract was sitting in the barn, the ICV froze up, which resulted in a near-inability to idle when first started (tried to idle around 450 RPM), with no ability to deal with dropping back to idle after revving, or even after turning on the headlights or the A/C. The observant would have noticed that the usual under-hood quiet buzzing was missing. Also, the OBDII threw a P1550 code, which was sort of a giveaway. Interestingly, because of the adaptive nature of the OBDII system, after five or ten minutes, it "learned" that the ICV was stuck, and how far open, and compensated by setting a steady idle of 1500 RPM.

I looked up what I could find out about the ICV, which was essentially nothing, other than the fact that it can be cleaned, so I went out and took it off and checked it out.

The ICV is the way that the computer controls the engine idle, and keeps it steady regardless of temperature, accessory load, etc. It allows varying amounts of air to bypass the closed throttle valves, depending on the signals it receives, so the computer can control the air entering the system, which, along with its control over the amount of fuel injected, allows it to control the idle quite tightly.

All the ICV is, is a tube, with each end connected to a passage in the intake manifold, with a sort of a rotating "flapper valve" that can interrupt the flow of air through the tube, controlled by an electrical solenoid, which cycles it open-closed at an appropriate duty cycle to admit the desired amount of air.

Nothing to it, really, bit if you want a new one, it'll cost you $150 to $200.

Removing it is easy - it's held on by two T-30 Torx screws, and has a flat gasket between it and the manifold.

Once it's off, you can look into it and see the valve that bounces back and forth. It should be movable, with a bit of resistance and bounciness because it sits in a strong magnetic field, which will make it want to sit in one or another position.

If it doesn't move freely, or if it is obviously blocked up, it can be cleaned.
Others have suggested carb. cleaner, but be advised that this thing has one internal O-ring, which could be damaged by carb cleaner, and may swell and make it impossible to reassemble the unit if you disassemble it further.
There's no rocket science here - try to avoid scratching the thing up too much or bending it, but you don't need to remove every last scrap of crud that you find in there - it's just letting air in so the motor can idle, it's not a high-flow, high-performance part.

If it's really stuck like mine was, you may need to take it apart.
The unit consists of two halves, held together with little cams, like the bolt of a rifle. The cams are parallel, not angled, so it doesn't tighten, and it has no "on" or "off" direction - it will come apart and go back together either clockwise or counterclockwise. It is prevented from rotating open by a thin brass roll pin, which you may be able to pull or pick out, but which is probably easiest to drill out. The hole can probably be threaded to accept a small screw, or you could just force or glue any solid bit in there - it's just to keep it from rotating, which it would be very unlikely to do anyway (I left mine without anything in it because it was tight enough to feel secure).

Once the roll pin is out, just rotate the halves in either direction about a quarter to a third of a turn and it should pop open. It will be a bit hard to pull the two halves apart because of the powerful permanent magnet in the valve half - you're not going to break anything, just pull them apart.

Inside, you will find an O-ring sealing the two halves and a spring washer that puts pressure between them so it's hard for them to rotate apart or rattle.

You can now grab the magnetic end of the valve half, which used to be inside the other half, and rotate it back and forth to loosen the valve. Some carb cleaner or penetrating oil may help loosen things up. Play with it until it's floppy and loose.

The whole thing just slips back together. If you got carb cleaner on the O-ring, it will be swelled up, and you may not be able to fit all of the parts together. Any hardware store should have a replacement. Just push it back together, line up the cams, twist, and align the roll pin holes, and you're all set. As mentioned above, use your own ingenuity to stick something in that hole to keep it from opening up later on.

Reattach with the two screws. Use a small amount of any innocuous sealant on the gasket. Tighten to about 5 foot pounds (like you would for screws, not like you would for bolts).

That's all there is to it, an easy way to save $200 and God knows what a shop would charge for the labor.

Enjoy the photos.

- Eric

Thanks - could be useful to me down the road.:smile:

Nice write up. I've been trying to find something on this the past few days!

Many thanks saved me ££££
 

Great write up, I had the same problem for a while with loss of power and poor idle speed.
My trusty 318ti guided me to the fault when the Idle Speed Control valve started buzzing loudly, then armed with your great guide it only took an hour to sort.
Just been for a test drive and she is back on form.

Cheers
Jim:smile:

Glad you liked it, Jim.

Since writing it, I have a few additions:

If you put the valve together without using something for the roll pin to keep the two halves from moving with respect to one another, they will move.

You will find that rotating them very slightly one way or the other will make the idle go up or down. This is pretty cool.

You want the idle to be in the right place, though, so that everything works right, no matter the load (lights, wipers, A/C, etc.). With the engine warmed up, try different positions under different load conditions until you seem to have a good compromise - tiny movements can make a fair amount of difference.

When you think you've got the setting right, drive around for a while to be sure, then lock it in. I coated the appropriate surfaces of the outside of my valve with RTV silicone to glue it together.

The engine may take a while to fully settle into its new idle settings.
By a while, I mean months.
Mine hunted and generally had no idle home for at least six months before it settled down. That's a long time.
Sometimes, I'd stop at a light, and it would idle at 800.
Sometimes it'd bumble along at 450.
Sometimes it seemed to like 1500.
There was no predicting it from one moment to another, but it never stalled.
Then, over a period of a month or so, it stabilized.
One day I noticed that it seemed to idle at about 750 all the time, and, looking back, I realized it had been that way for over a week.
It has behaved itself well since then, even with the A/C on.
I assume that the OBD finally learned how the ICV worked, but I really have no idea why it finally calmed down.

All I know is that I was getting ready to fork over cold cash (that I should be spending on tires), and now it looks like I won't have to...

Good luck!

I think I'm having ICV troubles. My car idles pretty low at start up and then about 1100 - 1200 when the car is warm.

I'm getting a code on my Peake code checker that says the value is "mechanically stuck". I keep clearing the code and it keeps comig back.

Any thoughts??

I'd take it off and check to see whether it moves freely.

If it does, the computer may be wrong, and the problem's somewhere else.

If it's stuck, you can either replace it or try to free it up, which may work, saving you about $200, or may wreck the valve, which is no good anyway, and you're back to spending $200.

I was wondering if cleaning this all out, like you have show, will correct a "short" fault code pointing to the ICV. It seems that this is all on the mechanical side of the unit not on the electrical side. Any ideas or experiences? I am trying to fix this cheaply before spending a couple hundred bucks.

No experience with this, but if the computer is throwing a code that says there's a short in the ICV coil, then there's nothing you can do, and you need a new one. Presumably, it's measuring the resistance of the coil an throwing the code if there's too little.

If you knew the specified resistance, you could check it. There are three terminals (RH, Middle, and LH). Mine shows 38Ω between the RH and Middle terminals, and 20.7Ω between the RH and LH terminals.

Good luck!

I guess this is what i have to do. Clean this valve.
The problems started after i disconnected the battery for installing the cruise control and changed the old spark plugs with NGK recommended by BMW.
The first time i was starting the car after putting all back together i didn't have a steady idle. The next day it seemed to be everything OK.
But now i have problems when the A/C is turned on. When i stop the car the idle goes down and up for a few times. I will try to clean the ICV an i will post back the results.

I did a search for 318ti Idle Speed Control Valve and found this, I'm still looking through the results so here goes:

My 318ti ECU got wet with heavy rains, fuel pump wouldnt turn on, checked it was still good, worked, replaced the ECU, fed fuel to fuel lines, but doesnt turn over, rain shorted things out, something buzzing in the engine bay, I found it was the Idle Speed Control Valve - its buzzing after I try starting the car and taking the key out. So, will replacing this start my ti up?

I'm about to buy a valve and Im seriously trying to avoid a shop right now. Thanks guys.

Sorry, I can't tell you what IS wrong with your ti, but I can tell you that what you describe is normal behavior for the ICV - it buzzes constantly while the car is idling, to regulate the airflow, and continues buzzing for a few seconds after you switch the car off.

- Eric

FWIW, this post just helped me solve my P0505 code. When I would start the car up after it had sat for 1.5 weeks, the idle was sporadic and the car stalled out if I didn't give it gas. It drove just fine once I was rolling, so the problem for me was just at idle, mostly when the engine was cold.

So, I did this cleaning, reset the code, pulled the battery (both leads) and let it sit for 10 minutes (I did this as an extra step), and voila! Problem solved.

Many thanks!

You're welcome!

Glad I could help.

- Eric

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