Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Serious problem - any assistance appreciated

  1. #1
    Join Date
    Mar 2016
    Location
    Stogursey, Bridgwater
    Posts
    30

    Serious problem - any assistance appreciated

    I posted previously about a mot failure but decided this issue was best dealt with in a new thread.

    Our 451 failed its MOT on the emission test.

    So far we have replaced the Cat/Exhaust, and then the lambda sensors, but the test is still giving the same results as when it first failed.

    The MOT centre suggested that the results were indicating that the fuel mixture is so high that it is outside the ability of the first sensor to adjust it.
    The idle speed is also outside of the range set for a pass for the 451 at 950.

    Unfortunately, not being Mercedes or Smart specialists, the MOT centre say they cannot suggest where the problem might be.

    So - does this make any sense to others, and more importantly, can anyone suggest how I determine what is causing the problem or how to remedy it.

    So far we have spent over 400 on the problem and we are no further forward.

    HELP!!!!

  2. #2
    Join Date
    Feb 2011
    Location
    Lewes
    Posts
    712
    You could visit a Merc dealer or Independent Dealer with full Diagnostic kit and get the ECU software updated.

    John

  3. #3
    Join Date
    Jun 2015
    Location
    Somewhere on the Wirral
    Posts
    131
    One could think of it inversely, how much air is getting into the engine? I'd go and see if anything was blocking up the air intake. I'd also go and see how warm the engine is getting... is it getting up to regular temperature? If the car thinks it is colder than it actually is, then it'll try to add more fuel into the mixture when it doesn't need to. I guess all the regular service items have been done? Possibly also the Fuel Pressure Regulator?

    I do sympathise though, my 450 is having the same issue although the idling speed is OK (it is forever failing on CO emissions at the moment).

  4. #4
    Join Date
    Oct 2013
    Location
    Swindon
    Posts
    199
    Could you post up a pic of the emissions test
    2001 Jaguar XKR 100
    2003 Roadster Coupe Bluewave Brabus SB2
    2002 Ex Fortwo Pulse


    Smart,Mercedes & Jaguar Diagnostics

  5. #5
    Join Date
    Mar 2016
    Location
    Stogursey, Bridgwater
    Posts
    30
    Quote Originally Posted by Heinkeljb View Post
    You could visit a Merc dealer or Independent Dealer with full Diagnostic kit and get the ECU software updated.

    John
    When was the last update released??

    The MOT centre put the car on their diagnostic kit and found a few old faults which they cleared, but nothing that indicated anything that would cause the emission problem.

    Quote Originally Posted by macbut999 View Post
    Could you post up a pic of the emissions test
    Here is the first report

    emission1.jpg

    Here is the report after the cleaner was used

    emission2.jpg

    Here is the report after a new cat/exhaust was fitted

    emission3.jpg

    The last report (after the new lambda were fitted) is the same as the third report.
    Last edited by pewe; 14-03-2018 at 09:53 PM.

  6. #6
    Join Date
    Mar 2016
    Location
    Stogursey, Bridgwater
    Posts
    30
    Sorry, the images were reduced when I added them to the reply.

    They are here
    http://pewe.uk/smart/emission1.jpeg
    http://pewe.uk/smart/emission2.jpeg
    http://pewe.uk/smart/emission3.jpeg

    Hopefully they will tell you something.

  7. #7
    Join Date
    Apr 2009
    Location
    Ecosse
    Posts
    3,604
    A similar problem elsewhere on the 'net (different car) and the suggestion is faulty MAF, faults in which do not show as fault codes or prompt EML to light up. Does the 451 have a MAF?

  8. #8
    Join Date
    Jan 2015
    Location
    Devon
    Posts
    57
    The CO and Lambda figures match well, showing the rich condition isn't caused by e.g. an exhaust leak. One possibility is a faulty coolant temperature sensor, or thermostat. If the engine is running cold (thermostat) or the ECU sees the engine running cold (temperature sensor) then it will run the engine rich.

  9. #9
    Join Date
    Apr 2009
    Location
    Ecosse
    Posts
    3,604
    Another recommendation was to read the fuel trim data to see what the ECU is trying to do with the mixture. EG, it may be trying to lean it because there is a dribbling injector. Or richen it, as above post suggests, if it's getting poor temperature data.

  10. #10
    Join Date
    Nov 2004
    Location
    North Weald, Essex
    Posts
    109
    Can you plug a reader into the OBD11 socket & read live data?
    I know I can on my 450 using my Chinese Delphi DS105E unit. That way maybe you'll be able to see what the water temperature & MAF sensor are reading.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •