ICV Cleaning DIY

[nightdevils]

Originally Posted by jybute

clapton never cease to amaze.

I concur.

[Racer X]

any word on that s52 ICV write up?

[215BIMMER535]

great DIY i have an M52 motor but i plan to do this next time im home from school and have a heated garage to work in.. my house up here is in "the hood" and i hate workin on shit in the street

[Dudesky]

Just a note, or rather, a correction:

In the 2nd photo of this writeup, the part depicted is incorrectly identified as the intake air temperature sensor. It is actually known as the airbox thermostat, and is connected to coolant lines which warm the throttle body. It helps to prevent air condensation at the throttle body. Sorry for any confusion

[kyleabaker]

I just completed this DIY on my 1995 325is and I'm not sure if it helped or hurt my cars idle problem. I got to the control valve out fine and cleaned it up with a tooth brush and q-tips and rubbing alcohol, and it did clean up great. However, after letting it dry for about 15 minutes or so I put the hoses back on and placed the icv back in place, then after starting up my car the idling seemed to be more extreme than it was before. I thought it mgiht straighten itself out if I took it for a short drive so I drove down the road and came back and it still has alittle trouble. It almost makes the car tremble a little. Before I cleaned it, my car would bounce around between 250-1000 rpms when idling and slightly rolling, like upto a stop light or something..but when the car would stop rolling the rpms would stablize. now it seems like the rpms are unstable both while rolling and while sitting still. Has anyone had this problem before..and if so what do I need to do to fix it up?

Thanks for any help.

[3050rpm]

Just a hunch, but in your case the results may not be instantaneous, try taking the car out on the highway for a few miles, at highway speeds (obviously), then do some around town driving, it just may be that all the electronics have to reset themselves after having operated for such a long time with the ICV being as it was, it may take a bit.

[kyleabaker]

@3050rpm
I did as you suggested and it still seems a bit weird. Here is what it is doing..

When idling and the car is still: The rpm's stick around 700 or so, but bounce between 700-720 rpms. So it almost sounds like an american muscle car, lol. Almost sounds cool, but it just doesn't feel stable.

When rolling out of gear and idling: The rpms start at 1000 and slowly increase (like I'm giving it gas or something) to 1500 rpms the drop back down to 1000 and start over. Each time it probably takes ~5 seconds as it goes from 1000 to 1500 rpms then restarts. My check engine light is on now, so I'm gonna read the codes and see what they are saying. I'll post the error codes here as soon as I get them.

EDIT:
So I'm getting the following code: 1221 ..which is apparently..
1221 Oxygen Sensor (primary) The O2 sensor measures the mixture of the car. This code is generated if the sensor is unplugged or broken. Sensor values are read when the engine warmer than 70°C, and should be within 0.02 and 0.85 volts. Negative values indicate that the sensor needs to be replaced, and slow fluctuation indicate that the sensor is clogged with soot. Cars with catalytic converters that have been removed may push this code.

I don't recall seeing this check engine light before I cleaned the icv, so I'm hoping that it is just unplugged, but I'm unsure where this sensor is located. I will try resetting/clearing the errors and see what happens.

[3050rpm]

Hmmm, I don't know of any direct association between the ICV and the O2 sensor, unless the cleaning of the valve somehow led to readings that pushed the O2 sensor over the (approaching) edge (how's that for a technical explanation?). I recently had to have my sensor replaced when the car failed emissions inspection, and really hadn't been running all that smoothly either, e.g. hesitation upon moving from start, other stuff. For some reason, no check light came on telling me that the thing had failed. Replacing the sensor took care of that, as well as getting me past a re-inspection no sweat.

I also have a '95, and the sensor is located in a bear of a position, atop the converter, at a weird angle making access practically impossible. There is a special ratchet attachment that you can borrow from Auto Zone that'll do the trick (or you can buy), but even at that it certainly helps to have the added leverage of putting the car up on a lift.

O2 sensors last about 80,000-100,000 miles I think, if things haven't been abused (overly rich mixture being one culprit), so if yours is in that range it seems like time for replacement.

Have you checked hoses for vacuum leaks? Something like that may have something to do with the vacillating idle, and in getting at the ICV you may have wrestled with a few hoses that were on the brink.

Wish I could help more, but as they say, a little knowledge...

[Dudesky]

Before you replace the O2 sensor, pull your spark plugs to see what kind of combustion is going on. If they're fouled or wet with fuel or oil, you'l need to address the cause of that first, or your new O2 sensor will again be damaged. Sometimes the sensor just goes bad, but more often something else has caused it to fail.

The harness for the sensor twist locks together, so it's nearly impossible for it to get unplugged. Plus, if it were, you'd also get a code 1264: O2 sensor heater circuit failure.

[kyleabaker]

@3050rpm
Thanks for your help. I pin pointed the problem. It wasn't an actual hose that was leaking, but it was leaking air. The plastic piece that the shorter hose hooks into that connects it to the intake manifold was not pushed in all the way..

The short curved hose hooks into it and then that plastic piece hooks into the manifold, so I ended up pulling it back out and putting that piece in straight and put the hose back on it and it runs fine now! Thanks for the help. Now anyone else with the same problems will know where to look, hehe. I disconnected the battery cable to reset the check engine light and now all is well. Not sure why the o2 sensor was showing up faulty, but it is fairly new so maybe it was a false reading due to the air leak.

@Dudesky
Thanks for the excellent write up DIY. It helped a lot, it's just that the plastic piece came out of the manifold just a bit when I took the hose off. You might mention to twist the hose a bit to avoid pulling that plastic piece out. Other than that, this has been the most useful DIY I've seen!

[troyvelius]

I cleaned the ICV on our e34 1991 525i, so I'll mention that all I needed to remove was the big air intake hose, and a small hose that was in the way (very obvious to un-plug and replug). I spent quite some time yanking at the hose connected to the ICV, but I was able to stick a flathead screwdriver through one of the holes in the intake manifold to give me extra leverage. It was a pretty tight squeeze and I'm quite thin, so this isn't a job for someone with large arms.

The big hose from the ICV was incredibly hard to get off, but easy to get back on.
Too bad my ICV was clean... I think the rough idle must be a vacuum leak then.

Thanks for the write-up.

[edward]

excellent all the way around: diy as well as experience. my finding was the intake bellows had cracked between the first and second folds, inside and difficult to see. had to pull slightly apart to see light... suspect flexing at different engine vibes caused and, coupled with dirty icv and a hose crack right at that unique hose clamp, was causing all sorts of havoc. peace, ed

[Radix325i]

It was incredibly helpful.
Certainly in my M20B25 is much easier to access all parts of admission without having to remove the intake manifold.
Anyway they took me almost a month to do all the work of cleaning and maintenance.
I work for an activity a week to test the difference between a repair and another.
I went outside to the inside.
First change of air filter and clean the intake pipe and filter box
The following week I did the cleaning and change of thermistor flowmeter that goes into the basket in the pipeline.
A week later, i made a rejuvenation of the flowmeter, another DYI thanks tp Fede318i a friend from Argentina troght bme30.org.
3 days after, i clean the idle control valve (ICV), as described here, in this DIY.
In this part, use isopropyl alcohol, SONAX contact cleaner and 3M lubricant.

I must say that the changes were significantly positive for my old M20.
I am very happy now.
greetings and thank you very much Dudesky

[jay]

Can anyone tell me what happened to the photo's for this DIY ??
This photo links point to http://files.unitedbimmer.com/ub.c/Dudesky_E36, but this location doesn't appear to exist

[intactgalactics]

Anybody have pics for location of icv on 1991 e31 850i? My car is running rough and i have cleaned maf's and car still runs lumpy on cold start. However when either maf is unplugged, the car idles cold fine. I have replaced sparkplugs, o2 sensors, inductive pickup, fuel filters, air filters, thermostat, the list goes on and on... Hopefully someone can get me a pic of icv location for my car, as it is next on my list...
Thanks!