Author Topic: Other Idle Issues (Read 4113 times)

LeeThompson · « **on:** August 01, 2011, 12:18:08 AM »

http://m42club.com/forums/showthread.php?t=7757

I am getting really ticked at my problem.
At a cold start (ie over night, or several hours) the car starts perfect and purrs like a kitten.
However if I cut the car off for a few minutes, (Like to fill up or run into a store), the car will start and then just shut off. I have to hold the gas pedal down and rev the engine to get it to stay. I then I have to ease the tack down to idle, then it become a bit rough then smoothes out. If I just shove the car into first and start rolling, but I let the revs drop, the car will turn off, even hundreds of yards down the road if I coast down a hill and the tack hits idle speed.

Any help will be greatly apreciated.

All the hoses have been replaced when I painted the valve cover and intake manifold crinkle red. And a suggestion to me was a vacuume leak, but how do you look or test for that?

bmwman91 · « **Reply #1 on:** August 01, 2011, 12:55:11 AM »

Take the idle control valve (ICV) off and clean it with some carb cleaner. A sticky ICV is often a culprit. It's the cylindrical thing between the intake manifold & firewall.

LeeThompson · « **Reply #2 on:** August 01, 2011, 02:25:47 AM »

Thank you for that. I have tried for the last hour to try and get that thing off. I do not want to cut the hose's or harm the ICV. Is there a secrete to getting the hose off? I have penitrating grease but I do not want to use that incase it harms the ICV... or is that ok?

DesktopDave · « **Reply #3 on:** August 01, 2011, 10:50:35 AM »

If it hasn't been off in a while it'll be pretty sticky. On my e30 I had to unplug it, unbolt it from the manifold, pull the entire hose out & clean it up that way. It's really tight in there, twisting it "broke" the alu free from the rubber hoses.

LeeThompson · « **Reply #4 on:** August 01, 2011, 07:18:45 PM »

I some how managed to pull the two hoses that connect to the thing out from there respectable places, but I could not pull them from the ICV. :-(. They twist around the connector peice with ease but will not pull out. can I just shoot carb cleaner down the tubes to help clean the ICV?

monty23psk · « **Reply #5 on:** August 01, 2011, 07:47:46 PM »

Maybe you have the brake check valve. Does one end of the hose go to a big black plate looking thing against the firewall next to the fuse box, if so, then you do not have the ICV.

LeeThompson · « **Reply #6 on:** August 01, 2011, 08:02:24 PM »

You are correct. It goes right into the black thing by the fusebox infront of the the brake fluid resuvour. The pictures i found on google look similar to that. Are we talking about that bigger about the size of a small cup right on the back side of the manifold thing? Like having to take the manifold out to get to it? Or am I missing something? That manifold is a pain in the Arse to take off. Sorry for the noob questions I have learned to drive the e30 exceptionaly well, just starting to learn how to work on them

monty23psk · « **Reply #7 on:** August 01, 2011, 08:26:31 PM »

Yes, that cup thing is the ICV. Has electrical plug and a hose going on top going into the valve cover and one on the bottom. You dont need to remove manifold. To get space, remove the plastic cover on the firewall that covers the wiring going from passenger to driver driver. Has 3 clips you just bend a little to loose it. 2 on closer to the driver side. Then use a 11mm socket to remove nut from upper intake at the bottom of the ICV where the bracket is that holds it. Then slid top hose and as you remove ICV you loosen. I just did it now in 5 mins to meausure openings on ICV as I am getting a silicone for this side. Already did the other side.

DesktopDave · « **Reply #8 on:** August 01, 2011, 08:26:46 PM »

Yeah, that's the brake booster line. It has a check valve in the middle. Put that back on.

The e30 ICV is about six inches long, on a thick hose. If you look at the picture in post #2 on this thread you'll see it at the rear of the motor. It has a small connector at the base and it connects to the very rear of the upper intake manifold.

LeeThompson · « **Reply #9 on:** August 01, 2011, 08:35:16 PM »

No wonder why my brakes today did not work

. When I read your post dave I just saw you standing over the engine saying... "Yeah...... that's the brake booster line, put that back on." I know not funny now but what I had pictured in my head was. Ok awsome. when I get home from my work tonight I will be doing that then. Getting sick of my car shutting off after it was already warmed up..... You should hear the honks I get from time to time... Thanks Dave, Monty, and bimmerman

DesktopDave · « **Reply #10 on:** August 01, 2011, 09:44:59 PM »

There's one other thing I heard about...I had a similar problem with my M20 E34. It was listed as a BMW TSB...occasionally the car would take forever to start after running perfectly. It would take like five solid minutes to start the car, barely catching. I'd have to feather the throttle to get it to catch & stay running. It only happened occasionally but it was really annoying. The cause is a check valve in the output fuel line in the E34. It tends to wear out, then fuel bleeds back into the pump. The result is that the car won't easily restart when it's warm. I'm not sure if the M42 has one, but (if so) it's a potential cause as well.

Fuel can also bleed out from a faulty fuel pressure regulator, cracked o-rings, a clogged injector, etc. A pressure tester is invaluable for this sort of thing.

Try to find a common cause (length of pause, warm or cold, wet weather, etc) and that will determine if it's a fuel pressure problem.

bmwman91 · « **Reply #11 on:** August 01, 2011, 11:21:27 PM »

The M42 does not employ a check valve on the fuel pump. A bunked pressure regulator could be the culprit, but it seems unlikely to be a hot-start issue.

DesktopDave · « **Reply #12 on:** August 02, 2011, 07:31:26 AM »

I'd seen a few threads about it, maybe owners are adding one? I'll update this if I find a link.

bmwman91 · « **Reply #13 on:** August 02, 2011, 11:18:33 AM »

Perhaps the valve is integral with the pump? I have replaced just about everything in the fuel supply system & never seen one.

LeeThompson · « **Reply #14 on:** August 02, 2011, 04:48:13 PM »

So far so good. I was able to take the ICV off and cleaned it with Carb cleaner. Let it dry for a bit then put it back on. So far my car has not shut off and cranks without a hitch even when warm. Thank you guys so much!