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328 EU, runs with poor fuel mixture between 1500 and 4000rpm

Discussion in 'Technical Q&A' started by dirk, Oct 19, 2008.

  1. dirk

    dirk Rookie

    Nov 4, 2003
    33
    Europe
    Full Name:
    Dirk
    Hi,

    my EU 328 starts fine and has normal idle. But on driving when i close trottle and open trottle again,
    it seems, that the engine runs with poor fuel mixture with loss of power.

    I had checked all vacuum lines and the engine except the injection system is just overhauled, but there are all new injectors.

    I anyone an idea ?

    What about the warm-up regulator, can this cause problems with partial load driving ?

    Or the fuel distributor ?

    Has anyone similar experiences with a 328 or injected 308 or Mondial ?
     
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  3. fletch62

    fletch62 Formula Junior

    Mar 8, 2004
    333
    Fairhope, AL
    Full Name:
    Larry Fletcher
    #2 fletch62, Oct 19, 2008
    Last edited by a moderator: Sep 7, 2017
    Check the rest position of your air flow sensor plate. I think your car is non lambda, could you give me the Bosch number on the side of your fuel distributor? It will be 0 438 100 034, or 0 438 100 139.

    Larry Fletcher
    CIS Flow Tech Llc.
    251-929-3771
    fletch62@bellsouth.net
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  4. dirk

    dirk Rookie

    Nov 4, 2003
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    Dirk
    Hi,

    thanks a lot, part nr. is: 0 438 100 034.

    I have to look for the sensor position.

    Thanks

    Dirk
     
  5. st@ven

    st@ven F1 Rookie
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    Aug 4, 2008
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    Steven

    please tell me what exactely is done on the engine. What is just overhauled?
    does this problem occure when engine is hot or cold or both?

    ( i'm from the europe - netherlands so no time difference.)
     
  6. dirk

    dirk Rookie

    Nov 4, 2003
    33
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    Dirk
    Hi,

    overhauled heads, new pistons, all new gaskets, nice cpmpression on all cylinders and new injectors.

    Direct coil ignition, new wires, plugs and so on.

    With a measuring system, You see, when open trottle, that there is a lambda over 1.3.

    Dirk
     
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  8. dirk

    dirk Rookie

    Nov 4, 2003
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    Dirk
    Oh, i forgot,

    so hotter the engine so more poor fuel mixture.

    This depends on lower system pressure when hot, i think.

    Thanks

    Dirk
     
  9. st@ven

    st@ven F1 Rookie
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    just asking,

    do you KNOW mixture is poor or do you THINK it is poor?
    say it with other words, do you think there patrol lacking (or excess air) or do know it for sure.

    You can measure the amount of fuel comming from an injectors if you're not sure. use google to find the normal amount of fuel per injector with full no trottle and full trottle (lifting the airsensors-valve by hand)

    As you also changed your ignitionsystem, the problem could be there to (someting with your advantagescurves)

    What above the 4000 rpm, everything normal than again?
     
  10. dirk

    dirk Rookie

    Nov 4, 2003
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    Dirk
    Hi,

    Sensor position seems ok.

    Dirk
     
  11. dirk

    dirk Rookie

    Nov 4, 2003
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    Dirk
    Hi,

    above 4000rpms the engine runs fine.

    We measured poor running by a lambda measuring system and this shows 1.3 when open trottle.

    When turning the co-adjust screw in enrichment direction, it seems, that the point of poor
    running move a little to higher revs.

    What about the fuel pump, can this cause such problems ?

    Thanks

    Dirk
     
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  13. st@ven

    st@ven F1 Rookie
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    #10 st@ven, Oct 20, 2008
    Last edited: Oct 20, 2008
    i think that if the pump was at fault you would not have proper running above 4000rpm.

    co-adjust screw in normally only used for low rpm adjustment of CO-gas i though. it will change air/fuel ratio slightly over complete range so this explains what you see when adjusting it.

    Thew WUR?. The WUR lowers the toppressure in above the fueldistributors needle when cold thus enriching the mixture. It should not work the other way around so i do not think the WUR is the problem ( do you experience difficult cold starts?)

    above 4000 it runs fine but is the labda figure oke too? and for that matters: do you now for certain thr labde reading is correct?

    false air somewhere from?
     
  14. dirk

    dirk Rookie

    Nov 4, 2003
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    Dirk
    Hi,

    thanks, i have to look at lambda value at higher revs.

    But what kind of failure brings a faulty fuel distributor ?

    Actually i put a strobo light at the ignition cable, it seems that the
    front bank with longer wires fires not so good as the rear bank.
    Maybe its about the higher resistance so there is less current for
    the strobo light to detect firing.

    Thanks

    Dirk
     
  15. BAturb

    BAturb Formula Junior

    Nov 14, 2007
    371
    Australia
    Full Name:
    Allan
    I had a simmilar problem in that the motor would run rough and seem to not get the right fuel mix and have a slight miss, (85 mondial QV) it turned out to be a small hole in one of the plug extenders, replaced it and problems went away, but as you have redone your ignition I asume you have checked all this over
     
  16. st@ven

    st@ven F1 Rookie
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    #13 st@ven, Oct 20, 2008
    Last edited: Oct 20, 2008
    oke we go from there after you know more about labda

    But what kind of failure brings a faulty fuel distributor ?

    a faulty fuel distributor CAN spoil your mixture. I came across one once which indeed had a prblem causing it to give to much fuel. I di thing these distributors are very rare to go into trouble.
    I would not look at it only after sortad all other possibilities out

    Actually i put a strobo light at the ignition cable, it seems that the
    front bank with longer wires fires not so good as the rear bank.
    Maybe its about the higher resistance so there is less current for
    the strobo light to detect firing.

    As said in an earlier post your ignition might be causing the problem. Did you change wiring. change anything?

    you're welcome!
     
  17. fletch62

    fletch62 Formula Junior

    Mar 8, 2004
    333
    Fairhope, AL
    Full Name:
    Larry Fletcher
    Your Fuel Distributor is a non Lambda version. You need to check your control pressure, if you need the specs give me your warm up regulator number and I can send them to you. What country are you in? Also if you need your fuel distributor and warm up regulator checked out I can bench test them. If you need more test info contact me by phone or email. I am a rebuilder of fuel distributors and warm up regulators. If you are German my girlfriend Luise is German and speaks it very well.

    Larry Fletcher
    251-929-3771
    fax 251-929-0190
    fletch62@bellsouth.net
     

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