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Discussion Starter #1 (Edited)
Last week while sitting in rush-hour traffic I noticed my car was idling terribly. The problem was traced down to an adjuster unit in the intake manifold that had broken. $206 in parts later the problem seems to be fixed. I can't say this is causing everybody's problem, but based on the part and the problem I believe it is prudent for all fanatics to check this part on a regular basis. Details follow...


Car
2004 330Ci, 04/2003 Build, 86,660 Miles
Manual Transmission
New Bosch Coils installed around 50k Miles
New Spark Plugs installed around 80k Miles

Symptoms
Initially the car was idling roughly and the MIL (aka CEL/SES) light was off.
Car idled roughly regardless of cold or hot.
When the MIL did trip the codes were as follows
Misfire - Cylinder 1
Misfire - Cylinder 2
Misfire - Cylinder 3
Misfire - Cylinder 4
Misfire - Cylinder 5
Misfire - Cylinder 6
Misfire - Multiple Cylinders
System Too Lean (Bank 1)
System Too Lean (Bank 2)
MAF Sensor (can't remember the exact code)

Diagnosis
* Since the MIL originally wasn't on when the problem started, I took the car to a shop to have all fault codes read.
* The mechanic at the shop found the adjuster unit was broken, but was convinced the problem was vacuum-related.
* Mechanic tried other diagnostics, such as moving plugs and coils around, with no luck.
* It was getting late so the mechanic pulled the broken adjuster unit flap out of the intake manifold and put the adjuster unit back in.
* While driving home the "System Too Lean" codes were set. These did not happen while the car was in the shop.

Commentary & Lessons Learned
I still don't have a definitive understanding of what the adjuster unit does. However, based on the location of the part (the flap portion goes inside the intake manifold), I'm guessing the relative position of the flap determines how much air the engine gets. When the mechanic pulled out the broken flap, the unit was left wide "open", which I'm guessing caused the "System Too Lean" condition.

After inspecting the broken flap and the unit more closely, I noticed there was significant dirt build-up on the parts (see picture). I'm guessing over time this build-up eventually started restricting the flap's movement. Since the flap is connected by a plastic connecting piece, the excess build-up ultimately caused the plastic connecting piece to break and the part to fail.

I drove the car for several miles today after repair and noticed that the idle was smoother and also the throttle response was quicker. I believe prior to the part's failure the adjuster unit flap's operation was still restricted which caused incorrect air/fuel mixtures to be running through the engine when engine speed was changing. For example, RPMs tended to drop more slowly before the rough idle problem appeared.

Based on the amount of dirt that was on my adjuster unit, I believe this part may be responsible for more than just rough idle problems (and possibly stalling on steptronic cars). Since the adjuster unit is a physically moving part, there is no easy way for the computer to know that it's gone bad, other than throwing other errors. The adjuster unit is a fairly expensive part ($200), so it would probably be a good idea to pull it out every Inspection to inspect and clean. Also, it appears there is a small metal pin holding the far end of the flap, if the adjuster unit fails it's possible this small metal pin will end up somewhere in your engine. Preventative maintenance of this part is key.

EDIT: Looking closely at the second picture, it looks like the adjuster unit is made to be able to close 100%. With all the dirt deposits on the second picture, it looks like the adjuster hasn't been fully closed for a while. This might be causing some of the intermittent idle problems. Just an afterthought...

DIY Notes
Removing the adjuster unit requires two T40 Torx screws to be removed and then the unit can be pulled straight out. However, due to space constraints I recommend removing the airbox to allow you to push the intake hose down to give more room to remove the valve. When you pull the unit out you will have to angle it slightly upwards to remove. Installation is the opposite of installation, you will need to insert at an angle to get it to fit, it helps to hold down the intake hose.

The DIY Disclaimer
It wouldn't be a DIY without one! I make no warranties to the accuracy of this information or my commentary/beliefs nor do I take any responsibility to update this information should additional details arise. I take no responsibility for any problems you run into for following any of this information. If you are uncomfortable with working with your own car please seek advice from a professional mechanic.
 

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wow nice write up.. yeah I have a steptronic and sometimes the idle will go below 500 just for a second when I initiate manual mode... or come to a quick stop.... one time I rev'd it up in N (friend wanted to hear new dinan mods) then the idle was all messed up like it was giong to die or something, and was shaking, but when I took off it was fine.... I know you have a manual but does this sound similar to your problem.... I love new findings like this thanks!!!
 

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I'm guessing that's an idle control valve. If so all it really does is control idle by adjusting the amount of air that comes into the engine when you're not on the gas, sitting at a stop light etc...
 

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can you post the part number of that and a gasket if any... you have 330 so it might differ from a 2.5 but I can get an idea


thanks
 

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Discussion Starter #5 (Edited)
Part number for the new part is 11617544805, part number for the old part is 11617502275. RealOEM shows that a similar part exists for the 325, but it's a different number.

Commander... there is a separate part called "T-Shape Idle Regulating Valve", part number 13411744713. Like I said, I don't quite understand fully how this adjuster unit works. You could be right, it's possible it's used only to regulate idle vs. non-idle air intake. But it seems to me that it takes at least some time for the unit to go from an open-state to a closed-state... so maybe it has a function between the two states as well? Also, if the adjuster unit gets gummed up enough it seems it wouldn't be able to fully close OR open, so not only will idle be affected but regular running could be affected too. :dunno:

I think it's worthwhile to check if you have the time. The part's relatively easy to get out, easy to diagnose, expensive to replace, and with all these 330s having weird idle problems it might help.

Please keep us posted!

EDIT: There is also a two-pin electrical connector on the adjuster unit. To remove there is a metal clip you have to press "down"... really to the right if you're looking in from the front of the car. Also, there is no gasket, the orange stuff you see in the pictures is a rubbery built-in gasket sort of deal.
 

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WOW! I have to say that I had the same problems code p0171 and misfire in 1 and 5. I cleaned out the TB, adjuster valve, sprayed down the manifold and presto! It's like a night and day difference. Throttle response is a lot better and more power down in the low rpm range.:thumbup:
 

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That pictured unit has nothing to do with idle control. It is the manifold runner length switchover valve (DISA). The ICV is much smaller and behind the throttle body.
 

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MarvelPhx said:
That pictured unit has nothing to do with idle control. It is the manifold runner length switchover valve (DISA). The ICV is much smaller and behind the throttle body.

word. nevertheless, the post was very informative
 

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The original post was very well written and interesting, but as MarvelPhx mentioned, it was also technically incorrect. The DISA valve doesn't have anything to do with air/fuel mixture or idle speed. If it were to not switch correctly it could cause reduced throttle response in certain speed ranges, but the only way it could cause lean misfires is if it was the source of a vacuum leak, in the same way any gasket, seal or cracked plastic part can cause a vacuum leak. The DISA valve is not a common source of such leaks, so if anybody goes out and replaces this part because of a rough idle or misifres, they are likely to be disapointed at the results.
 

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I know this is a very old post. But I wanted to add some additional info to this topic.
After experiencing jumpy idle and SES light with code P0171 and P0173 for several weeks. I checked the intake houses for a vaccum leak and found nothing. Since I didn't want to spend the money on a new MAF until the last resort. I decided to take the adjuster unit out to have a peak and sure enough, the flap was broken. After a visit to my local dealer and $240 lighter (I know it was a but pricey, but I just didn't have the patience to get it online), I installed the new adjuster unit and reset the SES light. Took the car out for a drive and immediately noticed the smooth idle and better engine response. After a day of driving, the SES light hasn't come back (before the new adjuster, the SES would go off withing 30 mins of driving) The car drives like new now.
The original part # for the adjuster was superceeded by a newer part#. I suspect that the original part was know to be weak and it had to be redesigned. Th moral of the story is, if you have jumpy idle problem with p0171 and P0173 codes, take a look at the adjuster unit first. It will save you a lot of money in trying to swap other parts. In fact, if your car has over 50k miles, i'd recommend that you take the adjuster unit out and clean it up with some carb cleaner to prevent it from getting sticky and eventually breaking.
 

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+1

Lots of us on here have had these issues and it costs nothing to remove the adjuster unit and check it out for damage or even just to clean it out. It just eliminates one thing that may be wrong (and ultimately could be the culprit of rough idle) without costing a dime. It may not be everyone's issue, but it's sure an easy thing to check out.
 

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WOW! I have to say that I had the same problems code p0171 and misfire in 1 and 5. I cleaned out the TB, adjuster valve, sprayed down the manifold and presto! It's like a night and day difference. Throttle response is a lot better and more power down in the low rpm range.:thumbup:

What did you use to clean the DISA valve?

ChevyGuy: Would CRC MF cleaner work? :str8pimpi
 

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For Future Reference



M52TU ENGINES - (323 & 328)
06 ADJUSTER UNIT -- 11 61 1 440 049
07 T-SHAPE IDLE REGULATING VALVE BOSCH -- 13 41 1 744 713



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

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+100 imho.

Just changed mine out, was too the culprit of rough idle, boggy responsiveness, poor gas mileage/performance. Be careful when replacing though as if the unit is broken, there is a small silver peice/screw/insert that can (and probably will) fall out inside your intake manifold so be sure to grab it. Also, check your old adjuster unit to make sure it is in there...if it's not, then time to look inside.

luckily, mine was just sitting on the tray.

anyways, thanks for the help, now ive gotta go get my 13 codes reset. (yes, 13)

hope this helps and thanks again to the op.
 

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unexpected improvement

I cleaned up the adjuster unit on my 2001 330i this weekend. The valve, though till in one piece, was stuck open. Not knowing if it still works, I gunked it and placed it back, and the improvement in low rpm range was significant. There's much more torque, and when the engine is cold it makes a lot less noise.

Before the valve was cleaned up, there used to be a whine coming from somewhere inside center console whenever the AC is on. The pitch of the whine changes with the rpm, and I thought my compressor or belt tensioner was dying. Now the whine is gone after the adjuster unit was cleaned up! Though it really doen't make much sense to me.
 

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hmm, not so fast...

yeah I know I just gave +100 to this post, but I have recently been getting more codes and it is still slugghish, has a stutter, and rough idle when at stop lights. Here are the codes:

P0300
P1351
P1345
P0171 bank1 x2
P0174 bank2 x2

I've searched the forums already and found other people with the same issues and codes, but no real fixes...yet. What do you guys recommend, coils next or o2 sensors? This is aggravating and I don't want to take it to the dealer to get ripped off.

please help!

Signed,

Rough idler/stutterererer
 

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emg2919, im having that same problem except i havnt cleaned this vavle thing on this thread, im going to this weekend. how do i clean it, where exactly is the valve located ?
 

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emg2919, im having that same problem except i havnt cleaned this vavle thing on this thread, im going to this weekend. how do i clean it, where exactly is the valve located ?
Item number 7 in the picture above.

In your engine it is on the driver side, connected to the intake manifold (right next to that pesky tube elbow).
 
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