Looks like I may have bad ICV...

[Warren N.CA]

'89 325is (The 535i working really good these days.)

Bentley has mucho info on bad idle problems. And what formerly was an intermittent condition has progressed to a very solid "won't idle worth a crap" situation. This is gratifying, because now I can have a good shot at fixing it.

Bentley says somewhere to remove the harness connector from the ICV while it's idling, and the idle speed should increase to 2K. Mine doesn't change much at all, and I have to keep my hand on the throttle to keep it running reliably. They also say I should hear humming and clicking from the ICV, but I can't discern any sound or feel any vibration.

So, as soon as I have time, I will perform the electrical checks of the idle/full throttle switch and the ICV, and the coolant temp sensor (If I can get the harness connector off- the fuel rail is in the way).

[ryan roopnarine]

this may not help you worth a damn, but when one side of my ICV hose fell off, the car would idle in the 50-100 rpm range. i know this isn't the same as an electrical fault in that unit, buuuuttt being disconnected like this threw off a 1222 code. my uncle the mechanic was able to drive the car home at 3-4000 rpm (floor it, run through stopsigns) on the one cylinder at a time operation. its a big vac hose, so it could be just that having that large of a leak would disable any engine. i've also noticed that ANY restriction (crimp, not ID) on the icv hoses make the car idle so low that it shakes and one must feather the accelerator to prevent the ever-present feeling that the car is going to die.

ps...have you inspected it/tried to clean it to see if its possibly "stuck"?

'89 325is (The 535i working really good these days.)

Bentley has mucho info on bad idle problems. And what formerly was an intermittent condition has progressed to a very solid "won't idle worth a crap" situation. This is gratifying, because now I can have a good shot at fixing it.

Bentley says somewhere to remove the harness connector from the ICV while it's idling, and the idle speed should increase to 2K. Mine doesn't change much at all, and I have to keep my hand on the throttle to keep it running reliably. They also say I should hear humming and clicking from the ICV, but I can't discern any sound or feel any vibration.

So, as soon as I have time, I will perform the electrical checks of the idle/full throttle switch and the ICV, and the coolant temp sensor (If I can get the harness connector off- the fuel rail is in the way).

[ryan roopnarine]

OH, i don't know if this has any bearing on your particular situation.....was trying to test a spare ICV that i have for my car. as you deal with electrics in your business, might one assume that you have an osciloscope? I specifically remember a specification from somewhere as to a 160 Hz square wave when operating (i guess by probing combinations until you found one that worked?).

ps...i have a different motor than you, so my osciliscope suggestion carries no fitness warranty with it, but if you can determine the a/c voltage on it, i doubt that its enough to blow an osciloscope up :D

[Warren N.CA]

my experiences. Now I need to determine if the problem is the ICV itself or its input signal. And if it's the input signal, what is causing the problem- probably one of three inputs to the DME or the DME itself (I only say the DME because I have a no-name chip from ebay in there.) It works great, but whenever I change from stock to performance chip, or vice versa, the engine has a dying idle for about a half hour while the DME adapts to the different chip (Go figure.).




this may not help you worth a damn, but when one side of my ICV hose fell off, the car would idle in the 50-100 rpm range. i know this isn't the same as an electrical fault in that unit, buuuuttt being disconnected like this threw off a 1222 code. my uncle the mechanic was able to drive the car home at 3-4000 rpm (floor it, run through stopsigns) on the one cylinder at a time operation. its a big vac hose, so it could be just that having that large of a leak would disable any engine. i've also noticed that ANY restriction (crimp, not ID) on the icv hoses make the car idle so low that it shakes and one must feather the accelerator to prevent the ever-present feeling that the car is going to die.

[Bill R.]

number of them where it made no change. Your best bet is to remove the valve and clean it with throttle body spray cleaner and then check it like so.http://www.bimmernut.com/%7Ebillr/images/idlecontrol%20valve.jpg






my experiences. Now I need to determine if the problem is the ICV itself or its input signal. And if it's the input signal, what is causing the problem- probably one of three inputs to the DME or the DME itself (I only say the DME because I have a no-name chip from ebay in there.) It works great, but whenever I change from stock to performance chip, or vice versa, the engine has a dying idle for about a half hour while the DME adapts to the different chip (Go figure.).

[Warren N.CA]

test procedure that requires only a DVM, making voltage and continuity checks. Worst problem I can see now is figuring out how to get the connector off the coolant temp sensor (without removing the fuel rail) , so I can measure its electrical resistance.




OH, i don't know if this has any bearing on your particular situation.....was trying to test a spare ICV that i have for my car. as you deal with electrics in your business, might one assume that you have an osciloscope? I specifically remember a specification from somewhere as to a 160 Hz square wave when operating (i guess by probing combinations until you found one that worked?).

ps...i have a different motor than you, so my osciliscope suggestion carries no fitness warranty with it, but if you can determine the a/c voltage on it, i doubt that its enough to blow an osciloscope up :D

[Unregistered]

Have you tried removing the idle control valve and cleaning it? Some WD40 and a toothbrush might do a lot to help fix or at least alleviate the problem.

While you're at it, triple-check the vacuum hoses, fittings, and clamps.

This helped my car a LOT.

[ryan roopnarine]

forgive me if i'm making a stupid comment, buuuuuttt.....

in pissing away the time before my math test at 7:30 today, i decided on a lark to run a 11/88 production 325i coupe and a 11/88 production 535i through the etk......it seems that you folks with the soviet-style intake manifold (i belittle to make myself feel better inside :p ) m20 and m30 MAY have the same p/n idle control valve on the cars, which if you are so inclined to check the numbers on each, means you could possibly take the icv off the 535i and put it on the 325i to check it. you'd just have to make sure the part is the same :D

[Warren N.CA]

BMWs that don't run, and I live over a mile from the nearest bus line, and they don't run after 8PM.) I think I'll just stick with Bentley's very clearly explained (for a change) testing procedure. This is the first time the Bentley manual has seemed really helpful.





forgive me if i'm making a stupid comment, buuuuuttt.....

in pissing away the time before my math test at 7:30 today, i decided on a lark to run a 11/88 production 325i coupe and a 11/88 production 535i through the etk......it seems that you folks with the soviet-style intake manifold (i belittle to make myself feel better inside :p ) m20 and m30 MAY have the same p/n idle control valve on the cars, which if you are so inclined to check the numbers on each, means you could possibly take the icv off the 535i and put it on the 325i to check it. you'd just have to make sure the part is the same :D

[Warren N.CA]

body has no clamps on either end. Do I just pull them off, and then push them back? Is any adhesive sealer used?

[Warren N.CA]

electrical checks indicate that the input signal to the ICV is correct, then that will be the next step.



Have you tried removing the idle control valve and cleaning it? Some WD40 and a toothbrush might do a lot to help fix or at least alleviate the problem.

While you're at it, triple-check the vacuum hoses, fittings, and clamps.

This helped my car a LOT.

[ryan roopnarine]

it seems like you're under the impression that simply removing/installing this item will impart radical ramifications onto the operation of your vehicle....that's why i suggested you swap, as if it doesn't work, you just swap back and drive the e34 to the e30 store. the only way its likely to damage something working is if by removing the hose you crack the end from the stresses. my icv hoses/unit has been on/off with no changes in vehicle operation so long as one does not try to start the car. it is prudent, if you feel that way, to leave the 535 alone until you've tried all the other steps, i guess. i have hose clamps on the end of mine for extra sealing, but it doesn't come that way. pull on/off, spray some o2 safe cleaner, rinse, repeat until it isn't gucky any more, and try. removing this component isn't as drastic as, say doing something like removing an intake manifold, IE you don't have to worry about surface sealing affecting operation in that drastic a manner.


body has no clamps on either end. Do I just pull them off, and then push them back? Is any adhesive sealer used?

[JonE]

I would also advocate a good cleaning with throttle body cleaner, take ICV out and soak it good. also take the large hose off and clean the throttle body. This cleaning cured my poor cold starting situation with my '89 325ic. Good luck.

[Warren N.CA]

least one car for transportation. Whenever an inexperienced technician tears into a car, unanticipated bad things can occur. No way I will even cast a covetous glance in the direction of the 535's ICV, unless and until the other car is running, and then it won't be needed. That's because I KNOW what I don't know.



it seems like you're under the impression that simply removing/installing this item will impart radical ramifications onto the operation of your vehicle....that's why i suggested you swap, as if it doesn't work, you just swap back and drive the e34 to the e30 store. the only way its likely to damage something working is if by removing the hose you crack the end from the stresses. my icv hoses/unit has been on/off with no changes in vehicle operation so long as one does not try to start the car. it is prudent, if you feel that way, to leave the 535 alone until you've tried all the other steps, i guess. i have hose clamps on the end of mine for extra sealing, but it doesn't come that way. pull on/off, spray some o2 safe cleaner, rinse, repeat until it isn't gucky any more, and try. removing this component isn't as drastic as, say doing something like removing an intake manifold, IE you don't have to worry about surface sealing affecting operation in that drastic a manner.

[ryan roopnarine]

i was acquiescing with you in that (post)....it just seemed like you were worried about removing the icv from the 325....ie, no special provisions are needed wrt hose sealing for disconnecting the hoses from the e30 to clean it. if it was a t-shaped icv like mine, was gonna suggest that you reverse the hoses and see if it made a difference. the l-shaped one doesn't provide for that option though.


least one car for transportation. Whenever an inexperienced technician tears into a car, unanticipated bad things can occur. No way I will even cast a covetous glance in the direction of the 535's ICV, unless and until the other car is running, and then it won't be needed. That's because I KNOW what I don't know.

[Warren N.CA]

electrical checks first. If they reveal no problems with the electrical input to the ICV, then I'll remove it, clean, inspect, test, and replace, if needed. I'm kinda busy now, so it may be a few days before I have time. (When you work for yourself, you discover that you a have a more demanding boss than ever before, insisting that you work overtime for free, etc.)




i was acquiescing with you in that (post)....it just seemed like you were worried about removing the icv from the 325....ie, no special provisions are needed wrt hose sealing for disconnecting the hoses from the e30 to clean it. if it was a t-shaped icv like mine, was gonna suggest that you reverse the hoses and see if it made a difference. the l-shaped one doesn't provide for that option though.

[Warren N.CA]

I would also advocate a good cleaning with throttle body cleaner, take ICV out and soak it good. also take the large hose off and clean the throttle body. This cleaning cured my poor cold starting situation with my '89 325ic. Good luck.