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Inlet port shut off motor delete (CDI2)

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Alex Crow, Feb 22, 2012.

  1. Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    A popular mod now, is to disable the inlet port shut off flaps, particularly on 270 CDI (612) engines.
    This is usually done because of damage to the flaps from wear and tear, accelerated by EGR gasses.

    It is possible to replace the entire manifold, but at significant cost, and some of these cars are old and unloved now!
    Even if the manifold is changed, problems can still occur with the actuator motors (M55) jamming and signaling faults to the ECU.
    So, how to do without the system...

    To remove the flaps is simple, but leaves big holes in the intake manifold.
    To plug these holes, I cut short sections of 16mm threaded bar, tap threads in the holes, fit the plugs with superglue, and finally drill and lockwire them for good luck.

    With me so far?

    But we still have a problem, if the motor is removed, a fault code will be logged, stating 'M55 inlet port shutoff motor signal wire resistance too high'.
    Yes, the motor can be left in place and connected to the loom, and if working there will be no fault code.
    However, as is often the case, the motor may have heavily worn gears, and frequently jam.
    This will log a different code - 'M55 inlet port shutoff motor signals fault through ground keying', which simply means the integrated circuitry in the motor has seen that its mechanism is jamming, and has signalled a fault to the ECU by temporarily grounding out the signal wire.

    So, if the motor is worn and jamming, we have a problem, but we do not want to replace it with a new one, especially now there are no flaps fitted.

    Getting there now...

    So, to cut to the chase, all we need to do to avoid logging fault codes, is wire in a resistor between the signal (PWM) wire and the 12v wire to the M55 motor.I have found that values from 1k to 10k ohms work - 20k ohms is too high.
    I have opted for 4.7k ohms on my testbed, and so far all is well - no codes being logged.

    I should add that you can buy these mods on ebay http://www.ebay.co.uk/itm/Inlet-por...arts_Vehicles_CarParts_SM&hash=item1e6a7d237e , but they are rather more expensive than a 4.7k ohm resistor...
     
    Hugobears likes this.
  2. MechPhil

    MechPhil Senior Member

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    Brandfort, South Africa
    Your Mercedes:
    '87 260E
    Are there any adverse effects from removing the motor and flaps? If not, why are they in there in the first place? I have noticed these "throttle flaps" in the intakes of most new (about 2002 onwards) diesels of all makes and have had many problems (mainly due to jammed gears and damage from EGR) with them, but I have as yet not had one technician, engineer or other interested person give a good reason for the existence of said flaps and motors.

    That said, thanks so much for sharing this valuable mod, a friend with a C270 has been saving for months to have the motor replaced!
     
  3. OP
    Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    One supposed function of the flaps is to aid efficiency at low to mid engine loads - but when heavily worn, leaking and jamming, they are no help at all.
    Note that not all Mercedes Cdi engines have them, so they cannot be all that vital.
     
  4. rjevon

    rjevon Senior Member

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    Your Mercedes:
    ML 270 CDi 2002
    Can you describe how you removed the flaps ?

    Ta
    Richard
     
  5. OP
    Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    In the center of each flap actuator arm is a torx headed self tapping screw.
    Undo these screws, and pull off each arm.
    Then the flaps will simply pull out with a small plastic housing for each.
    When you have the flap and housing out, remove the flap from the housing, and refit the housing - otherwise the sealing ring will not be held in place.
    Note that you really want to tap the M16 threads with these housings removed.

    Seeing is believing, and it is all obvious once the manifold has been removed, and cleaned up.
     
  6. kebo57

    kebo57 Senior Member

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    Lanc's
    Your Mercedes:
    ml270
    Good thread Alex just done this one nylon 4 diameter
    plugs interference fit + under cut locking + wire lock
    coulpe of thousand miles now no probs flap motor wired up
    as normal as of yet mpg isn't going to be any worse
    I do regular trip 600 miles so will report back
    Kev
     
  7. Silver_Star

    Silver_Star Senior Member

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    Your Mercedes:
    W203.006, S211.208 Land Rover 90
    What is this wire lock / lock wire people are refering to? Some sort of thread locking paste/sealant?
     
  8. MechPhil

    MechPhil Senior Member

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    The "wire lock" is a method devised by aicraft manufacturers in the 20's. A hole is drilled crossways through the head of a bolt (i.e. through two of the flat sides of the hexagonal part). A wire is passed through this hole, and through the hole drilled in an adjacent bolt and wound up. This prevents the bolts from loosening themselves due to vibration or creep.

    So in the case of the threaded rod, you would simply drill holes through the protruding pieces of rod, thread a single wire through the holes drilled in both rods, and wind the wire up to hold the rods in position.

    Thanks for the info on the purpose of the flap. I've noticed during dynamometer tests on Toyota and VW diesels that the flap never moves while the engine is running. Not under any circumstances. It merely closes when the ignition is turned off, opens halfway when the ignition is turned on, and fully once the engine is started, so I could never imagine the purpose of it (except ofcourse to break and be expensive).

    It is useful on VW 1.9's when the engine is hard to start, to hold the flap (vacuum operated in this case) closed while cranking the engine. This reduces compression, allowing the starter motor to get the motor up to higher speed, and letting the injectors deliver a good amount of fuel. If the flap is then suddenly released, the engine often fires!
     
  9. Silver_Star

    Silver_Star Senior Member

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    Your Mercedes:
    W203.006, S211.208 Land Rover 90
    Thanks Phil, that makes sense now.
     
  10. jj1975

    jj1975 Senior Member

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    Your Mercedes:
    w203 c220cdi 2002

    Hello Alex

    I do have c 220cdi w203 year 2002 manual gear box can i do same thing
    with my inlet manifold ??
    Thank you
     
  11. OP
    Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    Yes, your car has the same m55 motor as the 270cdi.
     
  12. Naraic

    Naraic Moderator

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    2005 CL500.
    Would this work on the V6s...or am I completely off the mark?
     
  13. OP
    Alex Crow

    Alex Crow Senior Member

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    I cannot remember if the 642 has a 3x or 5x wire M55, if a 3x wire then possibly.

    There may be other issues arising though, such as airmass faults being logged due to the slightly higher than expected air flow. Sometimes airmass deviations are logged as EGR faults, as this is the main system of monitoring the EGR system.
     
    ajlsl600 likes this.
  14. OP
    Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    A chap in liverpool asked me about this late last week, a coincidence. I suggested the mod.

    He fitted the 4.7k ohm resistor to his ML270, and it has been fine, throwing no codes in relation to the M55.

    So it works on the ML270 as well.
     
  15. kebo57

    kebo57 Senior Member

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    Your Mercedes:
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    Hi well I got my test run in no flaps blanked off
    holes motor wired as normal felt sure I would get
    that magic 500 miles of a tank of diesel but bottled it
    at 495.2 miles 76 mph cruise next services where about
    20 miles further on fuel needle was level with bottom of
    reserve warning light, I got 460 miles necked to reserve light
    coming on, power might be up a few % & I've had
    495 with nackered flaps, a bit less smoke on acceleration
    all in all fuel is up maybe 1 mpg to 34 mpg
    7 hrs at 75 mph does take some willpower though
    Kev
     
  16. stumo

    stumo Senior Member

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    Location:
    VIC, Australia
    Your Mercedes:
    ML270CDI 2002 facelift| Sprinter 316CDI 2003 LWB
    Is it possible to just wedge the flaps open and disconnect the motor? Or would that be a bad thing? Is it best just to wait until they crap out and then pull the manifold and delete, or should it be done as preventative maintenance? I have at least one flap seal weeping oil for the past 4 years.

    I can also confirm that the OM612 as fitted to the Mercedes Sprinter 3/4/616CDI van here in Australia has no manifold flaps (and has no EGR and no cats). It also has a full alloy inlet manifold instead of plastic.

    Unfortunately the Sprinter manifold has the 5 runners coming out like a big 'U' shape so its way too tall to fit under the bonnet on my ML270 - without cutting a big bonnet scoop lol.
     
  17. Tim85

    Tim85 New Member

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    Your Mercedes:
    2001 ML270 CDI
    Alex,

    I came to do this mod today. I have got .6w 2w and 3w resistors in 4.7k ohm. Will 0.6w be sufficient or is it just going to melt?

    Many thanks,
    Tim
     
  18. OP
    Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
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    Well, if we have a max of 14v across the resistor, and it is 4.7k, it will flow approx 0.003A.

    So 14 x 0.003 = 0.042 watts - any of them will be fine :D
     
  19. Tim85

    Tim85 New Member

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    Thanks mate. Looks like the .6 will be ample (excuse the pun) :)
     
  20. rjevon

    rjevon Senior Member

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    Your Mercedes:
    ML 270 CDi 2002
    Hi,

    I have a 2002 ML270.

    I am replacing my manifold with a modified one.

    How do I know which wire is which on the Shut Off Motor connector ?
    Are they specifically colour coded ?

    Richard
     

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