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Thread: 00' 528iT m52tu cold start rough idle and stall

  1. #1
    Join Date
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    94 325i , 00 528iT

    Update:fixed! 00' 528iT m52tu cold start rough idle and stall

    Hello all,
    Been chasing this problem a while. Car starts up with no issues and runs perfectly for a few minutes. Idle slowly/gradually drops down to around 800rpm and then begins to surge/drop down to about 100 and then quickly back up to normal at an interval of about every 15 to 20 seconds until it eventually stalls. Once I start it back up again it's fine till the next morning or cold start cycle. Once the car is warmed up to normal, it's fine. No noticeable issues while driving, idling in traffic, etc. It's literally only during the cold start cycle.

    Items I've sorted or replaced:

    Vanos seals (with the Vinton orings)
    Dual temp sensor
    Air intake sensor
    MAF sensor
    02 sensors
    Cleaned ICV
    Intake manifold gasket
    Upper/lower Intake bellows
    Disa valve oring
    Plugs around 20k miles ago
    CCV and all associated hoses
    Various vacuum lines

    My peake code reader shows no codes so I took to my indy shop to have them check it out. No codes. They conducted a smoke test and no leaks and checked for leaky injectors to no avail.

    I also conducted my own test with carb cleaner to double check for leaks...there are none.

    I've read dozens of threads on this problem and the only thing I've seen that peaks my interest is a potential DME update that a few members mentioned.

    Figured I'd post here just in case one of you fellas have a thought or an idea I haven't looked at yet.

    Thanks!
    Last edited by tk59194; 04-20-2021 at 08:37 PM.

  2. #2
    Join Date
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    94 325i , 00 528iT
    Hate to keep throwing parts at it, but these are the items I'll be replacing in the upcoming months to try and resolve:
    Secondary air pump valve
    SAP vacuum line & pressure hose
    SAP (pump itself)
    New spark plugs again
    New coils
    Vanos solenoid
    Fuel pump
    Fuel filter
    Injectors

    Even if these things don't remedy the problem, all these parts have 120K miles on them and I'll consider it preventative maintenance. (Except spark plugs)

  3. #3
    Join Date
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    03 525it/5, 1967 GTO
    I had same/similar problem albeit on an M54. After replacing the Vanos seals, replacing the ICV and replacing the vacuum line on the SAP, the problem seems to have been resolved. I have performed a lot of the same maintenance you mention including rebuilding the DISA with the GAS kit, replacing the CCV, upstream O2 sensors, etc., but it didn’t stop until finishing the Vanos seals and replacing SAP vacuum lines. I too had no codes and believe this symptom is likely caused by a vacuum leak, in my case it was a cracked hose at the SAP valve under the manifold.
    “She’s the last of the V8’s, she sucks nitro...phase 4 heads, twin overhead cams...600 horsepower through the wheels, she’s meanness put to music...”

  4. #4
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    94 325i , 00 528iT
    Very much appreciate your response/feedback. Yeah, I actually replaced the CCV with the G.A.S. CCV. It's a beautiful piece and works great, but still have this damn ghost idle/stall issue. And it's only in open loop mode. That's the crazy thing. Anyways, the SAP valve and hoses are in route. Hoping it will resolve the issue, but I'm skeptical. Thanks again for your thought. Giving me hope!

  5. #5
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    94 325i , 00 528iT
    Interesting thing happened today. Started it up and it did its normal idle surging/engine miss. I removed the oil cap and put back on and as soon as I did no more miss/surge. Gonna keep searching but that tells me vacuum.

  6. #6
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    As you seem to know that's classic Vanos seals. Which is just what my 00 did before I did the seals, which cured it. An initially intimidating, but not really a difficult job. I know you said you replaced them, you sound like you know what you're doing, but any chance you might have screwed it up? I'd be tempted to pull it apart at least and maybe even replace them again. I've heard of the reprogramming, but my understanding is that was to eliminate the condition without replacing the vanos seals, as M54s which are very, very similar except for drive by wire, don't exhibit the same surge/stall condition with bad seals, all of which point to a combo of bad seals with specific engine management.
    98 328is
    02 525ita
    80 528i
    81 528ia
    and decades of owning and driving BMWs

  7. #7
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    Mike, I meticulously followed step by step instructions when I replaced the vanos seals. If memory serves me correctly, it wasn't an overly complicated job. But, I'll not say that I'm incapable of error. I suppose I could have screwed something up. My only issue with considering vanos at this point is that I have no symptoms once the car is warm. This problem exists only between cold start and normal operating temperature. No loss of mpg or torque or power at any rpm. I may pull the vanos back apart and recheck everything for good measure. Thank you Sir. At this point, I'm open to any/all suggestions.

    Tomorrow I'm replacing the SAP valve as well as the vacuum control valve and a little "check valve" and all associated hoses for SAP system. Fingers crossed.
    I'll add vanos to the list. Replacing it again won't hurt anything.

  8. #8
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    Update: alright guys, just replaced all components of the SAP to include vacuum lines, valves and salmon relay. Problem still persists. Re checked vanos all is in working order. The Viton orings are still like new. At this point I'm going to just start replacing items that need replaced anyways. Injectors, fuel pump/filter, and most likely the coil packs. I don't know what else to do. Again, problem only exists during warm up on a cold start.

  9. #9
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    Update: new NGK spark plugs installed. The old ones only had 20k miles on them. Upon removal, they were all black and "wet" and look as though engine is running rich.

    Upon installation of new plugs, still getting the cyclic studder during cold start idle, but car never did stall. Once operating temperature reached, car idles perfectly fine.

    So, problem still persists. Next in line is the fuel pump, relay, regulator and filter I think.

    TBC....

  10. #10
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    get the injectors rebuilt / tested

    Sent from my SM-G390F using Tapatalk

  11. #11
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    Roger that! Any recommendations for a reputable place to send them (website)?

  12. #12
    Join Date
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    E39, e46, e36, e30
    What is the oil temp reading? A faulty oil sensor can go real haywire and give all kinds off issues, should also be able to just disconnect it (the one in the oil pan)
    Stop replacing parts and do a real fault search with logging values while it's warming up. I can almost guarantee you will find something abnormally

  13. #13
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    Iceen,
    Oil temperature seems to be fine as I have no warnings on the dash. I'll check the sensor with a multimeter. The 528 does not give an oil temp on the dash like the M5 so I'm not exactly sure how to check the actual oil temp. I took the car to an Indy and they couldn't figure it out with their software. Again, there are no codes being triggered whatsoever. I'm down to do a "real fault" search, but lack the necessary equipment to do it. Can you recommend a good place to start and how I'd go about doing this? I'm just a shade tree mechanic which is why I brought it to a reputable shop to hunt this problem down, but I'm all for learning.

  14. #14
    Join Date
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    Quote Originally Posted by tk59194 View Post
    Iceen,
    Oil temperature seems to be fine as I have no warnings on the dash. I'll check the sensor with a multimeter. The 528 does not give an oil temp on the dash like the M5 so I'm not exactly sure how to check the actual oil temp. I took the car to an Indy and they couldn't figure it out with their software. Again, there are no codes being triggered whatsoever. I'm down to do a "real fault" search, but lack the necessary equipment to do it. Can you recommend a good place to start and how I'd go about doing this? I'm just a shade tree mechanic which is why I brought it to a reputable shop to hunt this problem down, but I'm all for learning.
    tk....

    The faulty oil level sensor was a prevalent issue in the Z3's. I had yet to see it translate into the e39's...but like Iceen noted, it should be checked for sure because we all know how these cars can react to seemingly un-related part failures....lol.

    also, I saw you noted DISA o-ring replacement but not the valve itself or a valve rebuild. I'd be tempted to pull the DISA valve back out and make sure that the blade isn't loose on the shaft. Mine did the same oddball idle stuff as yours and found that the blade was loose on the shaft, essentially flapping back and forth in the intake airflow stream. I didn't have time to get the kit, but wound up hacking the repair by using a small piece of heatshrink on the DISA valve shaft, then pressing the blade back onto it. I wound up never doing the rebuild as the hack held so well. (edit: I used to have photos of this in my profile, but they look to be gone...)

    good luck in your search....but basic tools and some google-fu should help you determine how to properly test some things.

    also...you pulled both microfilter boxes and made sure you don't have blocked drains and water building up in there correct ????
    Last edited by adm750; 03-23-2021 at 03:57 PM.
    "two wrongs don't make a right...only three lefts do...."
    '79 Euro 635csi - gone and regretting it...
    '89 gsxr-750 - former traffic knife
    '97 528i sedan - holding on strong...(just sold after 16 years of ownership - sad day)
    '03 Euro 525it - something about a famous dolphin.....

    '06 Mercury Grand Marquis (don't ask....it gets the job done....)
    '84 Specialized Allez - full Campagnolo Super Record
    '99-ish Cannondale CAAD4
    "Stinky" - Kona Stinky Five
    '86 528e
    2008 E70 X5 3.0


  15. #15
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    AdM,

    Appreciate the encouragement. I'll check the disa flapper today. I have the microfilters/housings off now, so I'll check that too.

    Thank you! This is extremely annoying, but I'll eventually figure it out.

  16. #16
    Join Date
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    94 325i , 00 528iT
    DISA valve appears to be in good working order and I replaced the oring on it about a month ago. There are no blockages in the microfilter drains. New coils are going in next week and then I'm going to go ahead and tackle the fuel pump as a preventative maintenance item. I'll report back later.

  17. #17
    Join Date
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    528i, 525iT, M5
    Fuel pressure testing time.

    Install gauge on Schrader valve on fuel rail. Read PSI (50/55psi is what you are looking for)
    Start car, reading?
    Turn off car leaving gauge on rail, check back in 1, 5, 10, 24 hrs. Reading still at 55psi? If not see injector leaks, etc

    Clean injectors in car (25% chance of accomplishment) or out with an injector service 100% clean.
    Current Garage Highlights
    2003 525iT TiSilver
    2002 M5 TiSilver
    1998 528i KASCHMIRBEIGE METALLIC (301) (Goldie)

    Former Garage Highlights
    2005 X5 4.8is
    2004 325iTs (2x)
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  18. #18
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    94 325i , 00 528iT
    Stephen, I'll acquire a Guage and perform this test as suggested. Thank-you for the advice. Very much appreciated. Regardless of the outcome, I can't imagine any reason not to either have the injectors serviced or replace them at this point.

  19. #19
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    94 325i , 00 528iT
    Put the guage on. Reading is 45 PSI with engine off. At idle its 52psi. Turned car off, reading 40 PSI and holding.

    - - - Updated - - -

    With key on and all accessories off, guage reads 38psi

    Less than 24 hours later, guage is at 0 PSI
    Last edited by tk59194; 03-27-2021 at 07:11 PM.

  20. #20
    Join Date
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    To all who helped thank you!
    To recap, I replaced the following in the hunt to correct a cold start miss/surging idle problem:
    Dual temp sensor
    Air intake sensor
    Radiator sensor/fan switch
    Cleaned ICV
    Upper/lower Intake bellows
    Disa valve o ring
    Various vacuum lines
    Secondary air pump valve
    SAP vacuum line & pressure hose
    Fuel filter
    Fuel pressure regulator
    New spark plugs (NGK)
    New coils (Bosch)
    While I was at it, I also tackled replacing the Aux fan, and a few other bits that were looking worn (plastic stuff)

    The problem ended up being the MAF sensor. When I originally took it to a shop to have the problem diagnosed, they told me they swapped the MAF with a new one and that it wasn't the problem. I assumed they swapped my original back on. The other night while running diagnostics and looking at fuel trims on my new scanner, I noticed a white label on my MAF sensor I hadn't noticed before. The shop swapped my old MAF and had indeed left a new one on it. Didn't think much at first, but then decided to see what MAF they put on. Turns out, they put some remanufactured 29.99 ebay special MAF on my car. Ordered new VDO/Siemens OE MAF, slapped it on and BAM! No more cold start idle/miss/stall problem. Hope this helps someone out as I had no codes through all of this and it was an absolute head scratcher of a problem. Since I've already started the process, I'll finish up and go ahead and install the new fuel pump and get the injectors serviced as I had planned. Car ought to be running like a top!

    Thanks again for everyone's help.

  21. #21
    Join Date
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    Good you got it sorted. You definitely did a lot of other part updating but post-up once you’ve run for a bit to update if you see any mpg improvements with the new MAF. I’ve been thinking about getting a replacement for my M54.
    “She’s the last of the V8’s, she sucks nitro...phase 4 heads, twin overhead cams...600 horsepower through the wheels, she’s meanness put to music...”

  22. #22
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    Twistytee,
    I definitely will. I have to think the combination of new maf/plugs/fuel filter/coils will yield better mpg. Will update with results.

  23. #23
    Join Date
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    2000 328i sedan
    I know this thread is ancient, but thought I should share my related story.

    2000 328i (yeah, I know) with M52TU motor, no codes
    Engine rpms dropped very low, every 15 - 20 seconds as engine warmed, starting after a minute or 2, resolving when engine reached full operating temp.
    Replaced plenty of parts over 6 years, rebuilt vanos, cleaned IAC valve. Nothing helped.

    Last week, right as rpms dropped, I heard a rattly noise from exhaust vanos solenoid.
    Ordered a new solenoid (Amazon, $35) and a 32mm deep socket.
    Socket wouldn't fit over solenoid body, so I used a crowfoot wrench instead (1 1/4"). It worked perfectly, solenoid popped right out.

    Car runs fantastic now, no rpm drop, pulls stronger than ever.
    Last edited by GregoryW; 05-28-2023 at 01:16 AM. Reason: added info

  24. #24
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    Good to hear a fix that worked. It sounds like the original poster went to vanos issues right away, replacing seals, and even a solenoid (post#2). Maybe just not the bad one?
    -Donny

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