M30 ICV Problem

[WVe28]

Okay my car has the common erratic idle where it revs itslef to about 1500 RPM and then cuts off and repeats. I have used the search feature and found several informative articles on the ICV and ICM, however when trying to find it on my car to diagnose, it seems nonexistent. When following these directions, "The ICV is a dark plastic or silver-colored metal cylinder 3.5" long and 1.5" in diameter mounted on top of a two-legged support bolted to the valve cover near the firewall," I find absolutely nothing mounted to the valve cover except for maybe the airbox, and I don't remember that for certain. There are two holes about an inch apart toward the back of the valve cover. Could my problem be that I don't have an ICV, or am I just a dumbass who can't follow directions? Please advise. Does anyone have pics of exactly where it should be?


Car is 1982 528i - unsure if it has original engine or not. I have found several parts on the engine that when googled (Part numbers), I find are specific to 1980-83 745i, so ????

[Rich in Tupelo]

ICV on the M30 is connected to the rubber tube that runs form the AFM to the TB. It is on the side toward the firewall.

[Alpine34e28]

Try unplugging the cruise control cable, I had the same problem in my e34. I replaced the throttle switch and ICV, neither solved my problem, so I disconnected the cable and could have saved myself about $300 if I did that first. Good luck.

Edit:Sorry just read it again, you know what the problem is, I was suggesting another alternative. Good luck.

[WVe28]

Okay, I still can't find it. I've posted some pics. Maybe somebody can tell me exactly where it is from them, or even edit a pic and circle the part if it's there.






Edit: man my engine still looks so freakin dirty! I spent at least 4 hours on it the other day.

[Rich Euro M5]

In the last pic that nylon Tee is where the ICV would be in a Montronic equipped engine. It appears someone pulled the ICV and installed a Tee which is normally used in the heater hose running under the intake manifold. What I think is happening is the Montronic thinks you should be at idle due to the TPS. It is sensing the high RPM at idle and shutsdown the injector at 1500 RPM. It then senses the lower RPM and fires the injectors giving you this oscillating RPM symptom you're describing

I also didn't notice a loose connector laying about for the ICV. It's a fairly large connector which has three connections in a single row.

Since this is a Euro car, I suspect you have a kluge of parts that have been coobled together to get it running. A '82 528i could have been a L-Jet car or a Motronic equipped car that didn't have the ICV. Many Euro cars with dirty engines had a Auxillary AIr Valve (AAV) mounted in a different location. on the head and plumbed into the ICV ports to control cold/hot idle. The valve has a bi-metallic strip which allows controls the opening of a disk within the AAV as the engine warms up.

Rich

[DCB535is]

That plastic tee is right, that's whats shown in the ETK. I couldn't find a ICV in the ETK. It seems it just uses the air valve under the intake manifold. I'd follow those hoses and see where they go. There should be a cast engine size number on the block near the oil filter. This is probably a 2.8 with a 3.2/3.4 intake for the emissions b.s.
Where are the vac. lines running for the distributor? I noticed the port on top of the throttle body is capped. In the ETK it shows this port going to a electric solnoid valve, then to the rear port on the dist. The front port on the dist. goes directly to a vac. port on the bottom of the throttle body.
So many modifications have been done to the engine control systems it's going to be difficult to troubleshoot. If you had the info. on what the factory euro set up was, I'd take out all the added on junk and set it up the way BMW intended.

[Rich in Tupelo]

Rich is correct. The plastic T is where the ICV should be.

[DCB535is]

Check out #13-51-1-267-745

This isn't a Motronic car, it doesn't have a ICV like we're used to.

[Mike W.]

This isn't a Motronic car, it doesn't have a ICV like we're used to.

I think you're right, does it have a conventional distributor, with a vacuum box and adjustable timing? If so, it's not Motronic.

It seems like I saw an Motronic 82 732 in a yard one time with an Aux air valve on it, instead of an idle control valve. They used those in E21's and the last couple of years in US spec L-jet cars. They are just a warm up device, they have a little heater in them that acts on a bimetal spring to close an air bypass port. Actually worked pretty well, except you needed A/C compensation with them. I forget where it bolted on, might have been the side of the head, might have been the valve cover

And none of this covers what might have been done federalizing the car to sell in the US. Some changed very little, some lots. Some were hack jobs, some did a good job.

And here I completely forgot about your original problem, the high idle!

I bet it should have the aux air valve somewhere around the plastic Tee that goes into the intake boot. It's getting too much air, so high idle. And the reason it's cutting out is the throttle position switch is telling it that it should be idling, and it won't let it idle past 1300-1500 RPM, so it cuts off fuel. Try unplugging the TPS and the cutting out should stop. And maybe check out RealOEM for what should be there. I doubt you even have the wiring let alone the electronics to run a idle control valve, I bet it needs an aux air valve, that would cut off that air bypassing the throttle plate.

[Mike W.]

OK, I finally found it. Here's the link to RealOEM,
http://www.realoem.com/bmw/showparts.do ... g=11&fg=35

It's part number 8, though I'm not sure how it all is plumbed in there. It says cooling system, but it's air, it's the intake. It might be mounted on top of the valve cover, just to the right of the oil filler cap in your first picture, or on the side of the head, on the intake side, in the same general neighborhood. With hoses running from it to the intake boot, and down by the cold start valve probably.

[WVe28]

Okay, so say when I look this evening, I find that my car doesn't have this part, either, for whatever reason. I guess I would need to buy one and figure out how to hook up. Do you know how it hooks up electrically and what controls it? I haven't seen any loose electrical connectors near it.

I will follow the vaccum lines later and see if I find anything else interesting. The car only idles like this about 88% of the time. Sometimes it will idle okay, but still a little on the high side --around 11-1200 rpm. I will try unpluging the tps later to see what it does, too.

[Mike W.]

Okay, so say when I look this evening, I find that my car doesn't have this part, either, for whatever reason. I guess I would need to buy one and figure out how to hook up. Do you know how it hooks up electrically and what controls it? I haven't seen any loose electrical connectors near it.

I've been playing with BMW's since the early 80's and Bav's, so I know pretty well how they work, but I can't say exactly on euros. But electrically, I would guess it is switched with the fuel pump, just straight 12 volts. It's just a basic 12V dumb heater device, nothing fancy that sometimes gets this voltage or that. Could be ignition too, but I'd guess fuel pump. The connector is just a standard 2 contact fuel injection connector, the same as the injectors themselves use. It might be black, but don't quote me on that. If you're missing it entirely, I'd kludge it with one off an E21 or better yet a 80-81 5/6/7 series car, they aren't all the same inside, but they're close, and the same on the outside.

[Rich Euro M5]

Okay, so say when I look this evening, I find that my car doesn't have this part, either, for whatever reason. I guess I would need to buy one and figure out how to hook up. Do you know how it hooks up electrically and what controls it? I haven't seen any loose electrical connectors near it.

I've been playing with BMW's since the early 80's and Bav's, so I know pretty well how they work, but I can't say exactly on euros. But electrically, I would guess it is switched with the fuel pump, just straight 12 volts. It's just a basic 12V dumb heater device, nothing fancy that sometimes gets this voltage or that. Could be ignition too, but I'd guess fuel pump. The connector is just a standard 2 contact fuel injection connector, the same as the injectors themselves use. It might be black, but don't quote me on that. If you're missing it entirely, I'd kludge it with one off an E21 or better yet a 80-81 5/6/7 series car, they aren't all the same inside, but they're close, and the same on the outside.

My Euro M5 has a Auxillary Air Valve vs the ICV, it's also a Motronic controlled engine without an O2 sensor input. It's my understanding certain Euro M30s were also offered with this type of Motronic /AAV configuration.

Like Mike as stated the AAV is supplied with 12VDC when the engine is running. Interanally the AAV has a disk which is mechanically adjustable to control idle speed. There's also a bi-metallic spring interconnected with the disk. When the engine is cold the disk is open further to bypass more air and cause a higher cold idle. The 12 VDC connection provides power for a heating element. The heating element slowly heats the bi-metallic spring which then lowers the idle speed to the specified warm idle value as the engine warms up.

Rich

[crispy]

DCB - awesome avatar! I've been watching it over and over for like 2 minutes now... gotta get back to work.

[WVe28]

Excellent info guys. Thanks a lot, and I will check it out. If anybody has an extra AAV laying around for some reason I'll buy it, as they're like $80 new.