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Thread: 318i vacuum leak near DISA valve

  1. #1
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    318i vacuum leak near DISA valve

    I finished rebuilding my M44 in my 318i (stock rebuild, but pretty much new everything) about 1,500 miles ago. Ever since completing the rebuild, the long-term fuel trim is at +20 to +28 percent, and in town it's getting about 18 mpg. Ouch. The car also needs to pass emissions in 3 weeks.

    I've replaced:

    - MAF (with another used, about $100)
    - 02 Sensor (req'd exhaust work, $180)
    - Pre and post AST+C intake boots (they were both cracked)

    I couldn't see where any other vacuum leaks could be from, so I took it to a BMW specialist and they smoked the intake. Unfortunately I couldn't be around when they smoked it. They identified two possible leak sources:

    - Vacuum lines from the fuel injectors
    - A leak from a possible crack on the DISA valve

    I replaced the vacuum lines from the fuel injectors, and no change. That leaves the DISA valve. It's about a $280 part, non-OEM. I can't see any cracks on it (I didn't remove it). Has anyone had experience with this part failing, or what the replacement procedure is? It looks like the lower intake manifold has to come out, which is a real pain.
    Last edited by FuelCell250; 08-01-2015 at 06:18 PM.
    Joel


  2. #2
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    On the m44, the disa valve can be removed by ubolting the dipstick from the manifold and rotating it out of the way and then undoing the 2 or 3 bolts that hold it. 10 minutes tops to take it out .. done it on my dads m44 before.

    Never heard of one cracking and letting air in but ...

  3. #3
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    Quote Originally Posted by slocar View Post
    On the m44, the disa valve can be removed by ubolting the dipstick from the manifold and rotating it out of the way and then undoing the 2 or 3 bolts that hold it.
    After thinking about it a bit more, I was wondering it it would be this easy. A local BMW shop quoted $850 ($350 part + labor) to do it, so I assumed that it would be much harder. I'll try it and report back.
    Joel


  4. #4
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    It is definitely a DIY repair if you have the time. The part number should be 11611438404, they are typically pretty reliable I have not sold one in over two years. $850.00 is about right for a shop to replace the part.

    -Sean from The BMW/Mini Part Store-
    [Website]http://thebmwminipartstore.com/
    [Email] thebmwminipartstore@gmail.com

  5. #5
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    Quote Originally Posted by slocar View Post
    On the m44, the disa valve can be removed by ubolting the dipstick from the manifold and rotating it out of the way and then undoing the 2 or 3 bolts that hold it.
    Quote Originally Posted by TheBMWPartStore View Post
    It is definitely a DIY repair if you have the time.
    Confirmed, replacing the DISA valve on the M44 is super easy:

    - 3 bolts
    - Rotate the dipstick counter-clockwise
    - Move the BMW diagnostics port by pushing in the tab and pulling it up
    - Reach under the DISA valve to unplug it from the harness
    - Patiently wiggle the DISA valve out

    It's a tight fit, but it comes out in less than 10 minutes.

    I didn't find any cracks, but there is a rubber diaphragm in there that could fail and leak. I'm going to replace the top-to-bottom manifold gaskets first (cheap), and if that doesn't fix it, I'll replace the DISA valve without hesitation.
    Last edited by FuelCell250; 08-04-2015 at 01:43 PM.
    Joel


  6. #6
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    ^ If you end up replacing it, would you sell me your old one?

    Would like to try converting the complicated vaccum-electric m42 disa system to the simpler m44 system and don't really want to spend a fortune on it (at least not for figuring out what works and what doesn't for testing). I think it will fit with the m42 unit removed and the block off plate off and it should in theory work the same as it has constant voltage which is removed by the ECU at a certain rpm to move the flap.

  7. #7
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    Quote Originally Posted by slocar View Post
    ^ If you end up replacing it, would you sell me your old one?

    Would like to try converting the complicated vaccum-electric m42 disa system to the simpler m44 system and don't really want to spend a fortune on it (at least not for figuring out what works and what doesn't for testing). I think it will fit with the m42 unit removed and the block off plate off and it should in theory work the same as it has constant voltage which is removed by the ECU at a certain rpm to move the flap.
    If it turns out to be bad, I'll just give it to you. I'll be posting results here, but I'll DM you if it turns out to be need replacement.
    Joel


  8. #8
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    I replaced both the distribution hoses and the DISA valve that the BMW shop recommended, and it did not fix the problem Another $270 wasted. I don't know what to try next. I'm about $650 into this problem now. Recap:


    • Replaced intake manifold gasket ($10)
    • Replaced two intake boots ($60)
    • Replaced 02 Sensor ($108)
    • Replaced MAF ($100)
    • Replaced Idle Control Valve ($30)
    • Replaced upper/lower intake manifold gaskets ($8)
    • Had the intake smoked by a shop ($100)
    • Replaced vacuum distribution hoses (per shop recommendation, $40)
    • Replaced DISA valve (per shop recommendation, $230)

    I don't know what to try next. I'm very disappointed that the shop's diagnosis was incorrect. My emissions deadline is in two weeks.
    Last edited by FuelCell250; 08-12-2015 at 01:00 AM.
    Joel


  9. #9
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    For the worklog: I replaced the fuel filter today. No fix.
    Joel


  10. #10
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    Old thread, but curious if you ever got your idle issue resolved?

  11. #11
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    Quote Originally Posted by Sangatster View Post
    Old thread, but curious if you ever got your idle issue resolved?
    I think the idle issue was something separate... snagged cable or something like that. I ended up fixing the fuel trim issue by testing the fuel pressure and replacing the fuel pump. Let me know if you have any more questions.
    Joel


  12. #12
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    97 328i convertible 97
    It's actually a little rubber plunger so to speak inside of the disa valve that tears loose that will allow air to come through I'm finding out the hard way

  13. #13
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    1997 BMW E36 323i
    Did you check the fuel pressure? The fuel pressure regulator can die in different ways, giving lower or higher fuel pressure, and it can even cause fuel to be sucked into the intake manifold..
    I once had a difficult time diagnosing a no-start issue on an old E28, when I discovered that fuel pressure was at 6-7 bar.. In your case you'd suspect the pressure is too low and the DME compensates by adding more fuel. The most common cause though is a vacuum leak, but that can probably be ruled out by now.

    Did you read the error codes? Did you monitor the live sensor and fuel adaptation values with BMW INPA software? That can help a lot diagnosing the problem. If you do so, be sure to make a video recording of the different sensor and adaptation values, so we can interpret those for you.. Personally, booting up my laptop and starting up INPA is the first thing I do when something seems amiss with the engine running. Saved me a lot of time, virtually every time.

    Did you double check the exhaust and exhaust manifold? If air/oxygen can enter there, it can cause trouble too, causing the oxygen sensor to give false readings.
    What you could try, is disconnect the oxygen sensor connector and also the MAF sensor. If it drives a lot better, then the oxygen sensor giving false values (or a bad MAF, or a bad oxygen sensor) can be the cause. Removing MAF and oxygen sensor will force the DME to run off the factory/stock fuel and ignition map in the DME, if I'm correct. If you can reset the fuel adaptation in the DME (using INPA or other diagnostic tool), then you can also just remove the oxygen sensor and leave the MAF connected.

    Also, did you check the coolant sensor? Again, best to use INPA, because then you could immediately see all sensor values live and you'd be able to see instantly which one is giving strange values.

    Good luck finding the issue!

    P.S. If you don't have access to a laptop with BMW INPA, please find someone in the area who can run INPA on his laptop for you.. Shouldn't cost too much and will probably save you a lot of time and money.
    Last edited by ed323i; 06-13-2018 at 06:13 PM.


    1997 E36 BMW 323i
    (European) 265k km, with following small mods:
    • Chip tuned DME, supposedly giving 190HP and 260Nm (feels like it); 328i dual pipe exhaust (straight fit upgrade)
    • Fan delete mod (stock 92C thermostat, normal coolant, 80/88C temp. switch)
    • Throttle body coolant hose delete mod; Comprehensive ASC Delete option list (which I didn't delete in the end)

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