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E46 Xi Forum
The E46 XI was produced from 01-05 in sedan and touring body styles. Powered by either a 2.5L inline 6 in the 325xi or a 3.0L inline 6 330xi. Discuss all thing about BMW AWD E46 'Xi' here.

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Old 03-22-2014, 02:00 PM   #1
MontyVH
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Vacuum leak intake side, hard fix?

So I've had my 02 325xi for about 10 months, with 150XXX miles on it I don't expect her to win any races. Recently after a harsh winter it started to have a rough idle and miss in the morning. After the car gets up to temp it's not as bad but pretty bad when it first starts up. So I pop the hood and start looking around and grow what it sounds like is a vacuum leak on the intake side. I'm assuming at this point it's either the rubber pipe coming off the back of the air filter box, since it looks like it's been there from the beginning of time and is dry and not very flexible. Or maybe the gaskets between the intake and the head are bad.
Any suggestions on how to diagnose it further or how great of a mechanic I need to be to fix something like this myself. I'm by no means a mechanic, just pretty mechanically inclined. Any suggestions or recommendations are appreciated. 1st NEW POST!!! Ok GO!

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Old 03-22-2014, 06:13 PM   #2
YaSureYouBetcha
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Do a search on DISA and MAF, these are typical culprits when experiencing rough idle. Based on your mileage a DISA cleaning is certainly in order. If both are solid, then I'd recommend a smoke test to determine any vacuum leaks. Here again search, there are several procedures posted within the forum and on YouTube.



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Old 03-22-2014, 07:27 PM   #3
tomoyer
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You probably want to remove the air box, then remove the upper Intake Hose and inspect it for cracks on the bottom side, if no cracks there, then remove the lower Intake Hose from the Throttle Body and again, inspect it for cracks. Be careful removing the Upper Intake Hose as the "F" connector is easily broken. THe Lower Intake Hose is the one that usually gets the cracks more so than the Upper Intake Hose, but if they are both hard and not flexible, then I'd consider replacing them both (and just in case I'd also get a new "F" connector).
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Old 03-22-2014, 07:30 PM   #4
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Now if neither Intake Hose has cracks in them, then its time to remove the DISA Valve, the rectangular box attached to the side of the Intake Manifold. It is held on by 2 torqex screws. Inspect it to see that the plastic flap isn't broken and that it springs back. The DISA flaps break and depending on where the flap is stuck, you will either have rough/poor idle or poor performance along with throwing random Mis-fire Codes.
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Old 03-23-2014, 12:01 AM   #5
MontyVH
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Thanks guys for the advise, I'll be checking them out tomorrow and keep you posted. Thanks again.

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Old 03-23-2014, 05:40 PM   #6
MontyVH
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well i ordered both the upper and lower hoses, i figured it cant hurt to replace them even if they are still intact. I also ordered a new "F" connector. I've watched several video's pertaining to the DISA and how to diagnose if its failing and what causes it to fail. Im hoping its in good working condition because its going to be a little over $200 to replace if needed. Again I appreciate all the information you guys have supplied, its going to be a couple of weeks before i can get to it since I'll be going on vacation on Friday and I have to work this week. As soon as I have all the new pieces back in I'll let you guys know how it went.
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Old 03-24-2014, 07:58 PM   #7
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If you do happen to need a new DISA, check Amazon as well as eBay. I got a new DISA in BMW packaging off of Amazon a while back for like $75.00.
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Old 03-24-2014, 09:23 PM   #8
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Sweet, I looked at some rebuild kits but at that price might as well replace it if needed. Thanks again.

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Old 03-29-2014, 07:00 PM   #9
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Ok so I replaced the upper and lower hoses and checked the DISA it works fine. Car is still running rough. I've yet to get the codes reset but should ot really run this rough still?

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Old 03-30-2014, 10:33 AM   #10
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Have you inspected the SAP vacuum hose and plastic pipe? The Secondary Air Pump has a short piece of hose at the control valve and also at the rear of the intake and the plastic pipe runs around the rear of the head and down the lower side of the hear under the 02 sensor wires to the SAP Control Valve. Even though the SAP only operates for up to 5 minutes each time the car is started, if the hoses or pipe have a crack in them, it is a direct vacuum leak. Also, as silly as it sounds, are both o-rings on your oil dip stick? Does the oil filler cap fit snug? You really should have the codes read, written down and then cleared and after driving it a day or so, re-read to see what codes come out again.
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Old 03-30-2014, 12:36 PM   #11
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I checked everything coming from the SAP and it all looks in tact, the oil filler cap seems to be in order and the dip stick checks out. Prior to this i had the codes cleared with no relief, still runs extremely rough when it is cold but when it warmed up it seems to run just fine. I'll let it run a couple days and have the new codes rechecked and let you know what i find.
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Old 03-31-2014, 10:39 AM   #12
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same issue

Hey all,

My 2001 325xi is having the same exact issue. I started a thread here:

http://forum.e46fanatics.com/showthread.php?t=1028277

...but I'll follow this one as it seems more relevant.

In my case so far I have done the following:

- DISA check - flap springs back fine (swapped with another used one, no improvement.
- MAF - swap with another used but known to work well - no improvement
- Ignition Coils - unplugged 1 by 1. First three made no difference when unplugging. when I unplugged the 4th car ran much worse. swapped the first three coils with good used ones. no improvement.
- Sparkplugs -swapped the first three spark plugs with the coils - no improvement, however by looking at the spark plugs you could see that the car had been running rich (no wonder it's sucking up fuel).
-SAP - Runs extremely loud - that's my next stop.


On a side note while all this was happening I had to replace the water pump as it snapped my drive belt due to a worn out shaft. Replaced the T-stat as well while at it.
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Old 03-31-2014, 11:09 AM   #13
phildobaggins
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My upper intake hose was rotted through but you would only notice it when flexing it at the ridged bend point. Simple replacement and only like an $18 part.

All my vacuum lines look like crap after 129k miles. For now to get a good vacuum i'm just using black duct tape to seal them. After my current maintenance nightmare is complete I will replace ALL lines, DISA, etc... If you dedicate and replacement an entire system at a time it makes it easy.
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Old 04-01-2014, 07:21 PM   #14
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albokid SAP fill not have any bearing on the car running poorly unless the vacuum hoses and/or line are cracked, creating a vacuum leak. The SAP only runs when you start the car up and runs for 1 to 5 minutes injecting extra air to burn off excess fuel from starting. If removing/moving the coils on cylinders 1, 2 and 3 made no difference in the way the car was running, that would indicate either a problem with those 3 coils and or those 3 spark plugs. Since you also moved the plugs with no change (though rich/blackened/fouled plugs may not work right unless cleaned), now you have a few other things to consider and check. When you pulled the coils and plugs, was there oil in the spark plug wells? Were the coil boots oily? If so, this indicates that the valve cover seals for the spark plug holes are leaking and prolonged oil on the coils will shorten their life. Since you said the plugs were black/blackened, that would indicate a rich mixture or incomplete burning. Are the spark plugs all the same type? With a rich mixture, unless too much gas is being pumped into the cylinders by the injectors, means there isn't much chance of a fuel delivery problem. You know for sure that the "good used coils" you tried were in fact good coils? Are all the ground wires properly attached? Your 2001 has different coils and grounding than a 2003, so double check that. It might be coming down to you to perform a complete compression test to see if cylinders 1, 2 and 3 are lower than 4, 5 and 6. But before going that far, have you confirmed that both upper and lower air intake hoses are crack free? The lower one usually cracks the most and you can not see it/find the cracks without removing it and closely inspecting it. With crack(s) in either or both intake hoses, you will have unmetered air entering the intake and engine, but this usually results in a lean condition, not a rich condition.
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Old 04-02-2014, 11:18 AM   #15
albokid
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Quote:
Originally Posted by tomoyer View Post
albokid SAP fill not have any bearing on the car running poorly unless the vacuum hoses and/or line are cracked, creating a vacuum leak. The SAP only runs when you start the car up and runs for 1 to 5 minutes injecting extra air to burn off excess fuel from starting. If removing/moving the coils on cylinders 1, 2 and 3 made no difference in the way the car was running, that would indicate either a problem with those 3 coils and or those 3 spark plugs. Since you also moved the plugs with no change (though rich/blackened/fouled plugs may not work right unless cleaned), now you have a few other things to consider and check. When you pulled the coils and plugs, was there oil in the spark plug wells? Were the coil boots oily? If so, this indicates that the valve cover seals for the spark plug holes are leaking and prolonged oil on the coils will shorten their life. Since you said the plugs were black/blackened, that would indicate a rich mixture or incomplete burning. Are the spark plugs all the same type? With a rich mixture, unless too much gas is being pumped into the cylinders by the injectors, means there isn't much chance of a fuel delivery problem. You know for sure that the "good used coils" you tried were in fact good coils? Are all the ground wires properly attached? Your 2001 has different coils and grounding than a 2003, so double check that. It might be coming down to you to perform a complete compression test to see if cylinders 1, 2 and 3 are lower than 4, 5 and 6. But before going that far, have you confirmed that both upper and lower air intake hoses are crack free? The lower one usually cracks the most and you can not see it/find the cracks without removing it and closely inspecting it. With crack(s) in either or both intake hoses, you will have unmetered air entering the intake and engine, but this usually results in a lean condition, not a rich condition.
tomoyer, thanks for the reply. My valve cover will need to be changed, but the sparkplug wells were pretty clean, and the coils were dry. The other coils came from a 1999 328i, not sure if they are different, but I know that the 328i idles fine with the 2001 325xi coils and the 325xi still idles rough...so not sure if the coils are the culprit here. Same story with the plugs. Not sure on the type of the sparkplugs, now they must be different since I changed three of them.

This weekend I'll try to do a full vacuum system check. I know the upper intake hose is fine, but last time I looked at it, I didn't have time to go any further, especially since the bolts on the clamps were upside down and hard to get to.

I'm still extremely puzzled as to why the car idles fine after it's been running for a while If the car is hot (turn off and on immediately) it will idle fine after revving it up to 3-4K a couple of times..starting it in the AM idles like crap for a good 15-20 min, sometimes it even shuts off at a full stop.

As dumb as this might sound, could this be caused by a faulty o2 sensor heater? Maybe it's sending funny signals back to the ECU? Also can I test that there is juice going to the coils...do I just use a volt meter? ...and if so what voltage should I be looking for?


Thanks,

Al
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Old 04-06-2014, 04:24 PM   #16
scottyfix
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Al...did you ever come to a conclusion on your car? Reason I asking is? I have an issue on mine also ...almost exact. Best I can tell on mine is the intake is leaking air.

Thanks\ Scotty
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Old 04-07-2014, 10:28 AM   #17
albokid
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Quote:
Originally Posted by scottyfix View Post
Al...did you ever come to a conclusion on your car? Reason I asking is? I have an issue on mine also ...almost exact. Best I can tell on mine is the intake is leaking air.

Thanks\ Scotty

Hey Scotty,

Still not sure where the leak is...It's not the exhaust valve that hooks up to the SAP, changed that b/c the SAP was making a wierd whistling sound with the old one.

Whenever I resolve this I will update the thread...


Best,

Al
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Old 04-13-2014, 08:34 PM   #18
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More of "what's not" in my case:

ICV - cleaned it out today. Didn't make a difference.
VCG - It was leaking on to the headers so it needed replacement anyway.

What I noticed:
- No cracks in the upper and lower intake boots.
- The top of the engine/vc was pretty caked (difficult to tell from pic). I tried to clean as much of it as I could (not that it matters at this point). Also, the hose to the CCV valve major build up.




I know the next suggestion is going to be to replace the CCV valve, but that's no fun, and I would hate to do it just to find out it wasn't the problem.


Any progress on this issue from anybody else? Again the car idles fine once it runs for a while. If I re-start right after it's been running, starts rough but once I rev it to apprx. 3000rpm goes idles fine. Mornings are difficult.

Last edited by albokid; 04-13-2014 at 08:35 PM.
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Old 04-14-2014, 11:29 AM   #19
MontyVH
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I ended up taking my to an Indy mechanic who tracked it down to a vacuum house running between the engine and firewall. Cost about $180 to diagnose and replace. Car runs fine now.

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Old 04-25-2014, 01:59 PM   #20
albokid
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Talking

Just to update everyone for me replacing the CCV and the hoses fixed it. The hose that goes from the CCV to the dip stick was deteriorated. I would recommend cleaning the ICV and throttle body in the process.
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