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C320 cdi OM642 sometimes loses boost

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Cooper645, Oct 15, 2019.

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  1. Cooper645

    Cooper645 Active Member

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    Your Mercedes:
    C Class C320 CDI 2009 OM642
    Hi guys, new here and these forums have proved helpful for various jobs but I’m struggling to find the info I need.

    The issue is that I occasionally lose boost, sometimes cruising on cruise control, other times when accelerating hard to overtake and then the boost goes and I’m dead in the water with a sluggish car.

    The issue can be fixed with a key cycle and I can continue my journey.

    I have used an OBD2 and the following codes were thrown up:

    P0299 - Turbo charger low boost
    P1239(00) - Speed Fuel pump positive feed fault

    and the other day a CEL and :
    P109A(00)

    I have cleared the faults and not seen the P109A or CEL since, but the others still pop up.


    I plan to:

    -change the two red turbo seals
    -fit new air filters
    -fit new MAP sensor
    -have but not fit a crankshaft position sensor (don’t want to get caught out)


    considered possibly changing the fuel filter also.

    Anything else I should be checking for?

    Coops
     
  2. Larkone

    Larkone Senior Member

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    Your Mercedes:
    CLS 320CDI 2008
    Check that the turbo actuator is working OK. Worth pulling off and opening, cleaning out all of the black dust on the gear wheels and lightly lubing them with a high temp grease. Check that no wires between the circuit board and the connectors have burnt out. Tip - put a bit of wire through the circlip on the arm before you take it off so you don't lose it into the engine bay. The actuators can be re-furbed (several companies offer the service) but not replaced as they are matched to the turbo.
     
    Last edited: Oct 16, 2019
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  3. Larkone

    Larkone Senior Member

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    CLS 320CDI 2008
    Rather than changing the orange oil seal from the PCV valve to turbo it would be worth getting a new PCV valve as these degrade with age - the rubber diaphragm goes hard and/or splits. The current PCV valves have an updated orange seal at the turbo end which is an improvement on the old style.
     
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  4. OP
    Cooper645

    Cooper645 Active Member

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    Your Mercedes:
    C Class C320 CDI 2009 OM642
    EE6DF55C-89B8-4824-A6DF-9CD900F98DF9.jpeg C1089F02-6572-4740-B8C5-52FD2E00B082.jpeg So I removed the MAFs Y piece and had a look. There was a crack around the plastic that goes on the turbo and the little PCV valve on the left is the new type but didn’t seem tight. Should it be tight in there? And would the crack be the main issue?

    Also the fault occurred just before home today. The actuator wasn’t moving on revving the engine, after a key cycle it was back to normal
     
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  5. OP
    Cooper645

    Cooper645 Active Member

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    To update, the seals weren’t changed, they were the wrong ones. Think they were an older style.
    I have glued the crack and cleaned everything up and reassembled. Also noticed the feed to the left air filter was not 100% home, so shoved it back on. I’m sure the issue will still be there, but I’ll keep this post updated in case anyone else pops along with the same issue.
     
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  6. Wighty

    Wighty Senior Member

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    Your Mercedes:
    W211/E320cdi/2009 and CLK200k 2009
    Good fix , that red seal from the pcv is one of the newer updated versions already .
     
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  7. OP
    Cooper645

    Cooper645 Active Member

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    should it be snug to push in? Mines a little ..... easy
     
  8. bembo449

    bembo449 Senior Member

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    Your Mercedes:
    Mercedes Cl500, land rover discovery 3 , insignia vxr , shitron dispatch
    with the bonnet up flick the ignition on and off , the wastegate actuator should move everytime this is done , if it doesn't , its goosed
     
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  9. OP
    Cooper645

    Cooper645 Active Member

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    It does do this, it stops after the fault occurs. A key cycle restores functionality.
     
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  10. Wighty

    Wighty Senior Member

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    It's not a firm push , but neither should it fall out when it's in (don't anyone get off topic :rolleyes:)
     
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  11. Wighty

    Wighty Senior Member

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    Just as some further info on all turbo/inlet port motor area things , Fuse F44 in the engine bay fuse box is the fuse that governs things in this area , it's a 15amp fuse .
    Sounds like it might be worth taking the actuator off and looking at the issues Larkone suggested ?
     
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  12. OP
    Cooper645

    Cooper645 Active Member

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    So to update, the fault has remained after fixing the cracked inlet.

    I will look into stripping the actuator for investigation at my earliest opportunity and also look into fuse 44.

    thanks to everyone for their input so far, I’m confident that we shall have a fix soon
     
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  13. bembo449

    bembo449 Senior Member

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    when the actuator failed on my 221 it looked mint inside but was still fugged , the gear is usually to blame from what ive read but electronics side also goes south , got a refurbed one off fleebay , 2 years later , still all good
     
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  14. Wighty

    Wighty Senior Member

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    Another "free" job in this area could be to remove the exhaust back pressure sensor which is next to the turbo shield and spray clean the underside of it which has a small pinhole in it which can block up .
    24mm deep socket , but watch that a small silver washer underneath the sensor doesn't fall off .
    When I removed my actuator I did some research into a refurb one , I understand as Brembo said that it is possible but you have to exact match the turbo actuator model number to the one you have ?
    There is some YouTube stuff on checking the inside of the actuator and what to look for , one of the 4 outer metal wires developing a small crack is a common fault .
     
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  15. OP
    Cooper645

    Cooper645 Active Member

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    Thanks for the extra suggestions, I promise I haven't abandoned this post, just super rammed with everyday life. I have to get some tools out on Friday afternoon, but can't guarantee it. Touch wood I've only suffered once since the crack was fixed but I'm sure famous last words, Sods & Murphy's.....I'll suffer on my next trip out
     
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  16. OP
    Cooper645

    Cooper645 Active Member

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    So I have changed the MAP sensor on the LH filter, and also the air filters. These were horrid so I hope that I get a bit of ooomph back from some new ones.
    0C85E220-F997-470E-B11C-762ED7A321ED.jpeg 6D883D79-4326-4FA3-92B9-621A87948112.jpeg

    I’ll let you know how it goes with these changes.

    if still no improvement then I shall look at the actuator next
     
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  17. Wighty

    Wighty Senior Member

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    My God buddy :eek: , when were they last changed . At least the job needed doing regardless
     
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  18. OP
    Cooper645

    Cooper645 Active Member

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    god only knows, but I shall be doing them more regularly, the car sucks up everything apparently
     
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  19. Blobcat

    Blobcat Moderator

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    They look like they've been there since new...
     
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  20. OP
    Cooper645

    Cooper645 Active Member

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    ok, so the car seems "smoother", but seems to lack acceleration when driving in a spirited manner, I will try a TPS reset procedure before I set off for work in the morning and see if that helps.

    Could it be the ECU being slow to relearn how much fuel air ratio is required now it has fresh lungs?

    Fingers crossed for some time Wednesday to strip out and inspect the Actuator.
     
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