unplugged ICV... Runs Better?

[thebutcher37]

So car has been through 3 different Idle Control Valves and still has a hiccupy idle... Ive cleaned with brakleen and oiled with wd40 lately its been feeling like its going to cut out....

I recently went with a light weight m20 flywheel clutch combo, and it feels like its going to cut out once in a while if I let off the clutch pedal abruptly.

So today on a drive, it cut out, after a rough feeling idle. So adding to the problem my car wont start sometimes (need a new starter because when i hit the starter while turning the key car will start) So after few minutes car decides to start and has rough idle almost gonna die.. so i unplugged the ICV and car idles fine.

QUESTION IM ASKING IS:
What would cause my car to idle better with the ICV unplugged? Is driving with the ICV unplugged bad? Any insight or info?

Thanks for lookin.

[bmwm42]

i driven with mine unplugged made it a biaotch staying on when cold though other than that i didnt notice much of a difference though i did this with my m10 not my m42 shouldnt be any differerence though

[Ryann]

I'd guess you've got a nasty vacuum leak somewhere. Someone correct me if I'm wrong but I think the ICV controls idle speed by allowing controlled amounts of air to bypass the throttle plates.

[bmwm42]

Yup make sure you fix the mess under the intake pretty sure now you have a nasty vac leak check m42club.com lots of good info over there about this

[E30m42cab]

My 318is did this for a while until I found a bad wire on the Throttle Position sensor... I unplugged the ICV and it got me around for a while until I could fix the TPS wire. The wires in the TPS are very thin, and because I had taken my intake manifold off several times, the wire got stressed where it's crimped onto the TPS connector. Pulled back the sheathing on the wire and found the break. Might not be your ICV at all.

[slammin.e28]

WD40 isn't an oil. It's a penetrant.

Now that that is cleared up....get some ether (brake/carb cleaner/ starter fluid) and spray it around the vacuum hoses/connections. If the engine revvs up, you have a leak there. If you've done 3 ICV's my assumption would be that is not the problem. Correct me if I'm wrong here. After the 1st replacement, I would be looking elsewhere. Actually, I would test the original one, clean it, and visually verify it was working. If so, I would move on to searching for vacuum leaks. Don't throw parts at a problem. It only wastes money and time, and it's a bad habit to get into. Diag it and find the cause.

[jlevie]

As suggested above, intake leaks could easily explain why the engine idles better with the ICV unplugged. While you might be able to find some leaks by visual inspection or by spraying carb cleaner around, the best way is to have a shop run a smoke test on the intake.

[3bvert]

plug in the icv and unplug the tps see if a difference. I thought I had an icv probloem, replaced, still had, but I only had a miss at speeds between 2 and 3k rpm and a bad idle. unpluged the tps, all problems gone. replaced with aqnother, problem still gone. It will run fine and idle ok with out the tps.

however you could have a intake vacum leak. get rid of all that throttle body heater hose crap. only put on in america for smog reasons when cold. euro cars dont have em and they deal just fine with cold weather. I dont have one, but I dont see temps below 20 very often

also if you are going to spray junk around looking for leaks, dont forget to spray the big bellos that goes from the throttle body to the aircleaner and mass meter. not uncommon for those to have a crack

[thebutcher37]

Sounds good.. thanks for the heads up....

have been considering the mess under the intake!

TPS shall be checked.

[Ruskii]

Bumping this thread.

OP, did you resolve your problem? Because I am having somewhat same problem.

[thebutcher37]

Bumping this thread.

OP, did you resolve your problem? Because I am having somewhat same problem.

Hey Ruskii

It's hard to say honestly I feel it was a little bit of them both, the ICV and the mess under the intake as well... I found out that the ICV was bad, and I actually had someone who had a good working one on their car to diagnose this... But when I replaced my ICV it was discovered that I had some cracked hoses in the clutter under the heater plate, and those were replaced at the same time I had some work done on the car.

Bad thing is I only had my car back for about 3 days before my motor seized up. But I didn't feel any of the previous problems stated after doing the mess and replacing the ICV...


Hope this helped.

[Ruskii]

Thank you and sorry about your engine.
Yes I have done the "mess under the intake" and re-routed the vacuum lines with new hoses... so it only leaves the ICV.

Cheers!