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Ok so after thorough researching on this forum, I have finally fixed my "service soon light". There were a lot of information all scattered around, so I decided to compile them all together to help make it simpler for other fanatics out there. I am in no way of a professional mechanic, so this was all done through reading from these forums, so handle everything with caution.

My Situation -2001 BMW 330xi-m54 engine

One day I was driving my car the "service soon engine light" went off. My car is a 01' 330xi with about 64,000 miles. I did notice a slight change of my car before the light went off such as when I'm at a stop light my car would shudder/shake/ hesitant/rough idle. It would make like popcorn shakes only when I stop my car with the engine on. The first thing I did was to take it to an autopart store, which in my case was O'Riley and the codes read p0174 and p0171, which meant my system were too lean on bank 1 and 2. That also means that one of my oxygen detected a wrong fuel/air ratio.

Assumptions

1. Maf Sensor

2. Idle Control Valve

3. Vacuum Leak

4. Adjuster Unit

1. The MAF-mass air flow, what this does is it detects how much air is getting through, so it effects the fuel/air ratio. Therefore if it gets dirty it could throw off the system. The first thing I did was to clean the MAF sensor with some "CRC" cleaner, which can be found at most autopart store. Cleaning this was simple, it took a matters of minutes, but you have to be careful not to damage the sensor as it is very sensitive and the replace cost for this sensor is a whopping 400 some dollars. The first step you would have to do is to unclip the air filter box. Next you would take out the black plastic housing from the air filter by removing the o-ring. Now when you look through that black plastic housing you should see a metal pin and that would be the sensor, whatever you do, do not touch that, all you need to do is to spray it with your sensor cleanser about 10 times. That's it your done, now just put everything back together. However after I did this nothing changed as my car still shudders and my check engine light stayed on. On to the next step.



My next step was to check the adjuster unit: I will get back on this as I'm showing everything I did step by step, but when I first saw it, it seemed normal to me, so I put it back. (possibly could of save me a lot of time)
Rough Idle Fixed! Adjuster Unit Culprit - E46Fanatics

3. What I did next was to clean my Idle control valve, and here's the link on how I got that done: http://forums.bimmerforums.com/forum...d.php?t=900798

^^^The dude in here took out like half of the things in here that wasn't really necessary though. Some tools that you'll need would be a flat head and a T40 torx scewdriver. It was a lil' bit hard to find that size (t40), but I recommend on getting a small sized (length) torx screwdriver as it will be tight in that area. I also recommend a short flat head as my o-ring on the intake boot was a pain in the but to twist. There's also a sensor that connects to the idle control valve that was bit challenging to get out, I used to screwdrivers to ply it out. What you mainly have to take out would be the air intake box and the intake boot. It's located right under the adjuster unit. Heres some photos of what I took out for clearance of getting that control valve out.


M54 ENGINES (325 & 330)
07 ADJUSTER UNIT -- 11 61 7 544 805
08 T-SHAPE IDLE REGULATING VALVE BOSCH -- 13 41 1 744 713

I took out the entire boot since I also wanted to lightly clean the throttle butterfly. This picture was when I trying to take that last intake boot out, which took forever.



4. Finally as I was putting everything back together, I took a second look at my adjuster unit as I conscious about something I've read about on these forums about this one guy had a leak from here. At first glance everything seemed normal, until I really looked close that the outside rubber ring seemed a little thin. However they all seemed to be smooth all around and it seemed like nothing was wrong. My uncle suggested that over time and wear the rubber could of "thinned out", so we tested this hypothesis by spraying Carb spray to check for leaks and sure enough when we sprayed the vacuum would suck up the carb spray and the engine would start to shudder and the idle got rough every time we sprayed by the adjuster unit. I figure that this was the culprit of my problems. I went to the dealer to see if they sold the rubber ring around the adjuster unit, but they only sell the whole adjuster unit, which was about 250 dollars, yikes. So I went to an autopart store and I found a silicone for sealing gaskets under high temperature, surprisingly they were the same color as the rubber gasket, maybe even the same substance? After I applied the silicone over the ring and let sit while intact to the car for about 12 hours, the shudders and everything went away. I'm leaning towards that this was the main problem, but it could of been a combination, so I can't say for sure. My engine light did turn off after I clean my idle control valve and that was before I sealed my adjuster unit, however the shudders and the rough idles was still present but at a much less constant. So far I've been driving about 50 miles and everything seems fine and the check engine light stayed off, it's like a brand new car again finally, YES. I'll keep you updated how everything turns out. :excited:




This is my adjuster unit right before I put it back on my intake manifold.



I did notice a small crack on one of my intake elbow, right now it's temporarily taped up.



Notes

-patience is the key

-I spent about half an hour trying to look for my dropped screwdriver

-Spent another half an hour after a dropped a screw :slap:

Source
http://forum.e46fanatics.com/showthread.php?t=342081

http://forum.e46fanatics.com/showthread.php?t=572563&highlight=p0174

http://www.obd-codes.com/p0174
http://www.obd-codes.com/p0171

Everything under this search engine titled:
"p0714" and "rough idle"
 

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nice...let us know how it goes!
 

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I was the guy with the leak in the same spot. I'm starting to wonder how common this is.
 

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is this problem that common. i'm having the same issue. i just got the disa valve also. there is a few good post on this topic but none that i read as detailed as your. good job and good luck
 

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Cool, how did you fix the problem?

Exactly the same way you did. I used some RTV around the adjusting valve. As for how common....my guess is that if that valve has been removed in the past it's probably leaking. My leak was audible at idle. You could really hear it going SHHHHHHHHHHHH at idle. Now....the only problem will be getting the adjusting valve off in the future since it's basically "glued" in place now :eek:. I also discovered the source of the leak just like you did only I used some "starting fluid". Fixing that leak made a world of difference in my idle and cured some random misfires I was having.

Todd
 

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Hey Dan, what is the High Temp thing you use to seal the Adjuster Unit back to make sure it doesn't leak? I have to do that
 

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Exactly the same way you did. I used some RTV around the adjusting valve. As for how common....my guess is that if that valve has been removed in the past it's probably leaking. My leak was audible at idle. You could really hear it going SHHHHHHHHHHHH at idle. Now....the only problem will be getting the adjusting valve off in the future since it's basically "glued" in place now :eek:. I also discovered the source of the leak just like you did only I used some "starting fluid". Fixing that leak made a world of difference in my idle and cured some random misfires I was having.

Todd
I believe this is my problem, too I am getting random misfire and faulty o2 sensor codes. The adjuster unit was remove when my CCV was replace with the hose I think (shop did it, wasn't sure) and I removed it when I change my lower intake boot, to see what the hell it was.. I guess I can put the RTV to seal it properly.

Which one do you guys use, and how long did you wait for it to dry?

Thanks.
 

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Discussion Starter #12
Hey Dan, what is the High Temp thing you use to seal the Adjuster Unit back to make sure it doesn't leak? I have to do that
I used Versa Hem- High Temp RED-RTV Silocone-type 650. You can find this at any autopart store.



It takes about 12-24 hours to dry.
 

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Just be careful not to get the RTV near the moving parts of the unit. I used a product called "ultra-grey" or something like that. I had a tube of it at home because it's specified by many OEMs for things like oil pan gaskets etc. . It's easy to test if you have a leak in that location. Just spray some starting fluid (or carb cleaner) around the manifold to DISA valve junction with the engine idling. If the idle changes, you have a leak. If there is no change, either you don't have a leak or you just did not hit the leak.
 

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I didn't find either. I picket up the High-Temp Silicone RTV 650 Degrees, it's says it's for making gaskets, and can be use in high temp area like oil pan, etc... I've use that before on my valve cover gasket for my mustang I had and it work great. I'm sure this will work, I'll try to spray Starter fluid and see if it changes.
 

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Just be careful not to get the RTV near the moving parts of the unit. I used a product called "ultra-grey" or something like that. I had a tube of it at home because it's specified by many OEMs for things like oil pan gaskets etc. . It's easy to test if you have a leak in that location. Just spray some starting fluid (or carb cleaner) around the manifold to DISA valve junction with the engine idling. If the idle changes, you have a leak. If there is no change, either you don't have a leak or you just did not hit the leak.

any brand in particular, never bought this stuff before...
 

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any brand in particular, never bought this stuff before...
No. Pretty much any RTV sealant you can buy for automotive use is going to work. The intake manifold does not get overly hot and there should not be MUCH chemical exposure (there's some due to the CCV but not much). Anything specified for oil exposure will work great.
 

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^^^^thanks but I was asking about the spray/starting fluid/carb cleaner that's used to check if there's a leak...
 

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Ahhh...well...does not matter, you can use anything flammable really. Starting fluid is designed to be burned in an engine so there's not much danger in using that stuff (well....danger to the engine anyway). Just be careful and don't spray it on any ignition sources. Carb. cleaner usually works well too. The brand does not matter.
 

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Great compilation of scattered info on this!!

A question to the OP and the group. Instead of starting to tear down anything related to intake and manifold, wouldn't be better to just smoke or pressure test?

For example, (if you don't want to spend the money to smoke it) take the MAF sensor off, use an adapter that fits in the intake opening with a schrouder valve and build some pressure, spray soap solution and look for bubbles..

Would that have revealed the leaks you are describing?

Also, to add to the list of potential culprits, there are two rubber plugs at the very back of the manifold that will dry out and leak eventually...
 
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