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Thread: Issue with HC ppm too high

  1. #1
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    Issue with HC ppm too high

    Hi.
    Maby some one can give me a clue
    My 500e-93, has way to high hc.
    We find a issue whith the lamdasond,
    baugh a “original” Borsch.
    The hc was lower, about 469ppm,
    before we change the lamdasond it was about 540.
    We check the engine whith the Borsch diagnostics,
    and we not find any “strange”.
    The car is running very well.
    Someone give me a clue?

    Best Regards Niklas
    Gothenburg/Sweden

  2. #2
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    Re: Issue whith hc ppm, to high

    If everything else is normal, high HC readings are generally due the catalytic converters.

    Trying heating the catalysts prior to the test by driving at ~4000rpm for 5-10 minutes. You don't need high speed, 40-45mph (65-70kph) in 2nd gear works fine. With the cats fully hot, test again.

    However... 469ppm is REALLY high. Seems like a rich condition, maybe check fuel pressure, MAF readings, intake leaks, etc. I'd also want to check the adaptation values on the LH module (need SDS or other digital scanner).

    Is the test at idle speed (600rpm) or at higher rpm (2000-3000)? No load (test in Park), or driven on rollers / rolling dyno to load the engine?

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    Re: Issue with HC ppm too high

    when I'm fighting emissions issues I'd go through the ignition system, make sure it's FIRST rate...as well as fresh air cleaners.

    Do an oil change, 20/50...keep it a quart low, so refill with 7. That should put you half way on the stick.

    If it's a rolling road test, get the RPM's as HIGH as possible/the machine will allow for testing.

    I would typically drive a gear low on the way to the testing station, trying to keep RPM's up around 4K. I also try hard not create a high vacuum scenario w/ sudden lifting off the accelerator pedal.

    Rolling straight into the test station w/ Glowing catalysts helps too..

    So, what dave said plus a little bit. I've got cars that failed HORRIBLY to come back and read near nil after the above.

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    Re: Issue with HC ppm too high

    I found one place here which does a high-speed idle? Cars always seem to pass that test, where they have problems with the idle...


    M

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    Re: Issue with HC ppm too high

    Quote Originally Posted by jhodg5ck View Post
    when I'm fighting emissions issues I'd go through the ignition system, make sure it's FIRST rate...as well as fresh air cleaners.

    Do an oil change, 20/50...keep it a quart low, so refill with 7. That should put you half way on the stick.

    If it's a rolling road test, get the RPM's as HIGH as possible/the machine will allow for testing.

    I would typically drive a gear low on the way to the testing station, trying to keep RPM's up around 4K. I also try hard not create a high vacuum scenario w/ sudden lifting off the accelerator pedal.

    Rolling straight into the test station w/ Glowing catalysts helps too..

    So, what dave said plus a little bit. I've got cars that failed HORRIBLY to come back and read near nil after the above.

    jono
    Hi

    When we test with Borsch diagnostics,
    we found out tha we have low voltage 0,8mv
    In this case it seems like it will have more fuel,
    but the lands and hc is to high.
    Co is about 4,5%
    Hc is 465
    lamda is 0,85

    We are confiused

    We have better numbers without lamda connected in the car

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    Re: Issue with HC ppm too high

    You need to connect the SDS or digital scanner, to view the live data from the LH module.

    Have you confirmed that the LH module is the correct part number for the car, and has the stock/original EPROM chip inside?


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    Re: Issue with HC ppm too high

    Quote Originally Posted by gsxr View Post
    You need to connect the SDS or digital scanner, to view the live data from the LH module.

    Have you confirmed that the LH module is the correct part number for the car, and has the stock/original EPROM chip inside?

    Hi, now we just check the LH modul.
    The Mb nr is: 012 545 62 32
    and the Bosch nr is: 0280 002 512

    In the Bosch diagnostics should it be
    fore 500 se,sel for 02/91-05/93
    How do we now it’s the right or wrong LH modul?

    /Niklas

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    Re: Issue with HC ppm too high

    012-545-62-32 is the correct module for 1991-1992 Euro models.

    Do you have access to ANY spare LH module for a 5.0L engine? It doesn't have to be the same part number, just for 5.0L displacement, any year through 1995, from any chassis with M119 (124, 129, 140). It's an easy test to swap out the module and see if there is any difference.


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    Re: Issue with HC ppm too high

    Intresting you’re writing euro models
    This car is a Japan import,
    in the paper a 8/-93
    The chassis’s nr is maby a -91,
    the local Mb dealer tell us:
    1240361B496657
    We don’t have another LH modul

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    Re: Issue with HC ppm too high

    By saying “Yurro” he really means “non-USA” or ROW (rest of world).

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  19. #11
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    Re: Issue with HC ppm too high

    Quote Originally Posted by gerryvz View Post
    By saying “Yurro” he really means “non-USA” or ROW (rest of world).
    Correct - apologies for any confusion. The Japan-spec car would likely have 012-545-62-32 from the factory.


    Quote Originally Posted by Berglund View Post
    The chassis’s nr is maby a -91, the local Mb dealer tell us: 1240361B496657
    Your car was likely built around March 1991, per the datacard info at the link below. That's a super rare color combo; Pearl Black (199) paint with blue leather interior!
    https://www.datamb.com/vin/xGkZjydzQyZAb1YrR


    Quote Originally Posted by Berglund View Post
    We don’t have another LH modul
    You may want to consider picking up a spare module, even if it's not the same part number... as mentioned previously, any 5.0L M119 LH module will work for testing purposes. They can be inexpensive on eBay, however I'd try to find one that the seller claims is tested/guaranteed good, if you want to be able to swap it out and see if there is a change in the emission test results.

    It will be very difficult to diagnose further without an SDS, and also a mechanic/technician who is able to properly interpret the live data from the SDS.

    Have you tried disconnecting the MAF to see if that does anything?


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    Re: Issue with HC ppm too high

    Quote Originally Posted by gsxr View Post
    Correct - apologies for any confusion. The Japan-spec car would likely have 012-545-62-32 from the factory.



    Your car was likely built around March 1991, per the datacard info at the link below. That's a super rare color combo; Pearl Black (199) paint with blue leather interior!
    https://www.datamb.com/vin/xGkZjydzQyZAb1YrR



    You may want to consider picking up a spare module, even if it's not the same part number... as mentioned previously, any 5.0L M119 LH module will work for testing purposes. They can be inexpensive on eBay, however I'd try to find one that the seller claims is tested/guaranteed good, if you want to be able to swap it out and see if there is a change in the emission test results.

    It will be very difficult to diagnose further without an SDS, and also a mechanic/technician who is able to properly interpret the live data from the SDS.

    Have you tried disconnecting the MAF to see if that does anything?


    Hi, and thanks for all replay
    We find out what’s wrong in the car.
    The connection fore lamdasond in the car,
    was having two wiering that was in the wrong spot.
    The LH just get 12v and want get the engine more fuel
    Now when we swap the two wiering the HC/CH went just perfect.
    The car in now ok to drive.

    Best Regards Niklas

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  23. #13
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    Re: Issue with HC ppm too high

    Niklas,

    It’s great that you solved your problem.

    Your car is early 91 Japanese import with pearl black paint and blue interior. Apparently you have Raikku’s car. It would be nice to see some new pics of your rare color combo.

    Please post some pics when you can.

    Also, Where are you located in Sweden?

    Take Care
    Terry

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