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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 06-18-2014, 09:33 PM   #1
ebiz
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My Ride: 2001 330xi
engine sometimes stalling when returning to idle... vacuum hose issue?

So like two years ago when I replaced my valve cover gasket, I remember the end of the vacuum hose you have to move being all hard and cracked but I didn't have a spare, so I kind of glued it back together and let it ride. Things seemed fine so I figured no big deal.


http://bmwfans.info/parts-catalog/E4...vacuum_control

part 4

Fast forward and for the past two summers, when the A/C has been on and there's been a greater load on my engine... I'll be driving and take my foot off the clutch to come to a stop and my car won't always catch the idle RPM before it drops too low and it'll stall. If I'm rolling, I pop the clutch back out and it fires right back up... and when actually idling it's fine but I couldn't figure out what it was.

Well something tickled my brain the other day and made me think back to the vacuum hose... is that most likely the culprit here? I'm decent at working on my car but there are definitely gaps in my knowledge that keep me from being able to answer questions like that myself.

Thanks!
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Old 06-19-2014, 11:28 AM   #2
Zerohm
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I don't think it's very likely that these two things are related. Once the engine is warm, the Secondary Air System has very little effect on the engine. I also broke that very same hose while replacing my head gasket. I replaced it with a 98 cent section of hose from auto zone and have had zero issues.

I also get some inconsistent idle, but I don't think it's ever stalled. Sometimes my idle dips while stopped at a red light, sometimes it doesn't. The behavior has been off and on for years. I figure it's build-up related.

Last edited by Zerohm; 06-19-2014 at 11:30 AM.
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Old 06-19-2014, 12:40 PM   #3
ebiz
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Damn, that's disappointing to hear. To be clear, my idle itself is fine... it's just when the engine returns to idle that it's too slow to catch itself on the way down at times. It happens occasionally when the A/C isn't on, but very frequently when it *is* on.

I'm getting so tired of it, it's definitely gonna give me bad habits for my next stick car because when the RPMs are dropping, I'll blip the throttle just a tiny bit before it gets to idle to slow down the fall and kind of "catch" it in time to idle correctly on its own.
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Old 06-19-2014, 04:20 PM   #4
Tangent_
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Dunno for sure it'll help, but you might consider removing and thoroughly cleaning the idle control valve. If it's sticking it stands to reason it could cause those symptoms...
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Old 06-20-2014, 08:06 AM   #5
markusmarkus
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Did you have the ECU scanned for pending codes? That's always the first step!


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Old 06-20-2014, 10:46 AM   #6
ebiz
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Ah crap, I always forget that one... I just kind of wrongly assume that if there are ANY codes, that there'd be a check engine light.

I think I'll zip by auto zone saturday while I'm replacing my window regulator

edit: back from autozone, no codes but I got a can of carb cleaner and I might tackle the idle control valve this weekend... that doesn't look too involved

Last edited by ebiz; 06-20-2014 at 03:57 PM.
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Old 06-22-2014, 02:35 PM   #7
ebiz
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Okay, cleaned out the idle control valve yesterday. It was actually super straight forward and it looked pretty dirty. Squirted a ton of carb cleaner in there and did a little scraping and some paper towel use. By the end, it sounded like it was moving a bit freer in there, but I'm not 100% because I didn't shake it that much until after the cleaning was fairly done.

I'm not convinced this fixed it. I did idle differently after I cleaned it but when I was driving around town, there were a couple of times that the rpms dropped down to like 400ish before catching. I didn't stall at all yet, but that's pretty close to that range, so I'm not counting it out.

Either way, window regulator is replaced and my idle control valve is a LOT cleaner than when I started, so it was hardly a wasted afternoon. 160k miles on that thing at this point, it's nice turning back the clock on some items when I get the chance.
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Old 06-23-2014, 09:49 AM   #8
thailam515
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I am having the same trouble with my vehicle. I do not have a CEL and have not scanned it yet. I guess I could do that when I get home. Listed below are all the failed troubleshooting:

-Spark plugs; they were shot and full of oil. I replaced the valve cover gasket yesterday along with cleaning the EGR valve. I thought it ran fine, but once it got a little hotter outside, the idle kept dropping.
-Brake Booster vacuum line; dry rotted and disintegrated in my hand.
-Fuel regulator vacuum line; dry rotted and cracked.
-Checked the intake box to throttle body hoses; perfectly fine.
-Cleaned ICV thoroughly; it was stuck, but once cleaning it was free by shaking.
-Cleaned MAF with MAF cleaner from AutoZone.
-Cleaned DISA valve and replaced the o-ring.

I have ordered a fuel filter with a new fuel pressure regulator. I would love to know how you fix these idle issues. It is very annoying, but if I figure my problem out, I will post a reply.
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Old 06-23-2014, 02:25 PM   #9
ebiz
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Excellent, I wish you much luck! If I find a solution on my end, I'll send it along as well! Oh, and to confirm, I definitely got it to stall last night. It happens most when I'm in stop and go traffic... that kind of sharp acceleration and immediately getting off the gas seems to be the condition that it happens most in. If I just sit at idle and blip the throttle to 2k and let off, it doesn't happen as frequently as if I'm getting going to 5 or 10mph and then letting right off.

Last edited by ebiz; 06-23-2014 at 02:26 PM.
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Old 06-23-2014, 10:48 PM   #10
thailam515
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I just replaced the fuel filter and fuel pressure regulator. After test driving I noticed that I did not resolve my problem. It seems as if the idle can drop inconsistently and it is a little tough to predict when it will drop idle. The list below describes a couple of patterns that I have noticed:

-Idle drops more severely when it is hotter outside (>90F)
-It may be because the A/C is on
-Drops more severely whenever I am recirculating the air conditioning
-Sometimes drops when RPMs are from 1k down to idle, but more chances of idle drop when RPM is near 3k.

Overall, it is very unpredictable and I cannot find a solution. I know I have heard about so many different solutions and I have found 3 year old threads that may have been resolved, but the resolution was never included in the thread. I guess whoever is experienced with this please help us out. If it helps any, I have a list of the services done to my vehicle below.

-Oil Filter Housing Gasket, VANOS line (182k)
-Spark Plugs (<50 mi ago)
-Oil Separation Lines (170k)
-Clutch (169k)
-HVAC filter (160k)
-Fuel Pump (120k in 01/2009)
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Old 06-24-2014, 10:19 PM   #11
drew56
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Did u replace the hose to the secondary air pump or no? I broke mine changing my head cover gasket as well. Haha, but I stalled all the time too, I'm haven't been home in awhile to fix it, but it would stall on me whenever is start her, or shifting, I'd have to get out parking spots like a retard, flooring it as soon as it was in gear. Once I got moving tho, everything was fine, I'd pull up on a red light and sure I'd idle low but not stall.


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Old 06-25-2014, 03:13 PM   #12
thailam515
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I did not break the secondary air pump hose, but I did break the little plastic vacuum hose from the EGR valve. I was lucky enough not to break so much that I could just replace a longer rubber hose to it. I am going to check the DISA valve tonight. I have another E46 and I will trade just to test the DISA. Hopefully it will be solved tonight.
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Old 06-25-2014, 10:31 PM   #13
dakkon
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Look at the below link. See if it sounds the same as what your experiencing.

http://forum.e46fanatics.com/showthr...ighlight=stall
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Old 06-26-2014, 10:05 PM   #14
ebiz
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Quote:
Originally Posted by dakkon View Post
Look at the below link. See if it sounds the same as what your experiencing.

http://forum.e46fanatics.com/showthr...ighlight=stall
Very interesting information, thanks for linking it! When I get a chance to give it a shot, I'll report back with results!
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Old 07-09-2014, 04:12 PM   #15
thailam515
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ebiz, have you heard any good news? I am still having the same issues and I don't even know where to go from here....
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Old 07-09-2014, 04:34 PM   #16
tcphoto
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I would replace the vacuum hoses simply to eliminate the potential problem plus check the ICV grommet, throttle body gasket, Disa valve gasket and intake boots. Any air coming into the system past the MAF will cause a problem. How old is the CCV? The dipstick o ring in notorious for tearing and sucking in unwanted air. I'm surprised that you haven't had P0171 and P0174 codes along with a CEL light.
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Old 07-10-2014, 09:22 AM   #17
thailam515
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I have checked all of the intake hoses and they are actually very sturdy and not even flimsy one bit; they have been bent extremely to reveal any imperfections (during my visual inspection), but could not find any damage. To be honest I do see a small layer of oil on the CCV. I did throw out a P0171/P0174 at one point but cleaned the MAF because I ran a K&N (oiled filter). I cleaned the MAF and replaced the filter with a regular paper filter a while back and over 1500 miles later I still haven't thrown a code. DISA Valve was been sealed, checked and even replaced with another E46's DISA Valve. I guess I could check out the dipstick O-Ring and CCV this weekend. Also, sometimes when I am stopped at a light, the idle starts a very steady rise and drop in idle for at least 10 seconds. (the range is within 200rpms). I will post updates.
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Old 07-27-2014, 01:22 AM   #18
shaq858
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My 02' 325i with 120k miles stalled a few times this year at low speeds (usually when making u-turns). Idle sometimes felt weak in the morning.

Fix: Replacing the exhaust camshaft sensor (12147518628). Engine is definitely more responsive too.

DIY

http://forum.e46fanatics.com/showthread.php?t=492544
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Old 08-26-2014, 02:31 PM   #19
ebiz
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I have no good news to report yet. Other than the idle control valve, I talked to my bmw shop when I was just in there for an unexpected fuel pump replacement and they mentioned doctor VANOS. Well... it seemed really intimidating when I did my VCG a couple of years ago but I figured what the hey and ordered a rebuilt VANOS unit from drvanos and crossed my fingers.

The install itself was time consuming, although not too difficult and at the end, I was cautiously optimistic as the rpms seemed a tad higher generally on idle and I couldn't get it to stall in my casual non city driving.

Fast forward to today when I was heading out to the burbs for a client and ran into some heavy traffic. 5 or 10 minutes of stop and go traffic later and I had my first stall. After that, it was back to giving the throttle a little blip as the rpms were falling back down to idle, just to be sure there'd be no other stalls.

So, short answer is that the only thing I've tried since my last post was a new VANOS unit and that didn't do anything to help it.

I'm a little reticent to try the new DME flash because I forgot that my ECU is sharked from waaaaaay back and I kind of like that lack of a top end limiter and higher redline. Not that I've gone north of 120mph in a lot of years... but still, it's nice know that it's there.

Anyone know if the DME flash overwrite the shark?
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Old 08-26-2014, 07:03 PM   #20
Tangent_
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Quote:
Originally Posted by ebiz View Post
...
Anyone know if the DME flash overwrite the shark?
If it does I don't see why you shouldn't be able to just re-Shark it... Unless you lost the programmer.
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