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frequency valve/lambda control conversion Euro308QV

Discussion in 'Technical Q&A' started by RVIDRCI, Nov 20, 2007.

  1. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi
    Ok, here is one for the Brainiacs out there.

    So, I have to get the 308QV Euro smoged ( every 2 years in Calif) so while I have the prototype supercharger parts sent back to 928Motorsports for finalizing (polish, powdercoat, remachine etc.) I'm going to the test only station.

    When I did the California EPA conversion 2 years ago, the conv facility added a lambda control unit, frequency valve, O2 sensor, cats, and a charcoal cannister evap system. When I did the SC work I simply removed the fuses from the lambda electronics, removed the stock WUR and frequency valve system, and pulled the O2 sensor off. Everything went into protected and labeled storage for the future. The future is now.... and everthing is back on the car as it was, but it does not apparentley function. It seemed like a simple off and back on would work fine, but Nooo.

    My wide band data logger tells me I am running (quite well and smooth, btw) an air fuel between 11.8 and 13.5 under normal warmed up driving/accel/cruise conditions. The idle air fuel warm is set to 14.5:1 +/-. Warm up sequence is normal with the cold start injector, warm up regulator and aux air working as designed. If I test for 12v power at the 2 feeds ( one constant, the other powered along with the fuel pump etc. cir) to the lambda box, all is well. If I disconnect the plug to the frequency valve, there is no change in performance.

    Clearly, the lambda control system is not doing its job. But why. Can I check the O2 sensor, the frequency valve, the freq valve control connection for output or resistance values to confirm ? Thought I would put it out to the community of experts ( I do not include myself here) before I take it to the $$$$ smog mechanics to iron out.

    (the only thing that was ever done that may have had an effect on the sytem is this. My dyno tech used a injector driver to fire the feq valve in order to determine how it was working against fuel dist control pressures. We found that the freq valve and jumper line was being used to lower WUR control pressure by bleeding off to the tank return fuel circuit).

    The O2 sensor is a single wire, no heater.

    Any ideas?

    -Luigi
     
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  3. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,184
    Berkeley, CA
    Full Name:
    Brian Brown
    First, find the lambda control unit to see who made it. Most of them are pretty crappy (D.C. Johnson), and look like they were homemde with parts from Radio Shack. The only good one was made by Valentine Research, same company that makes the radar detectors.

    I have wiring diagrams for most units. They are pretty simple, power, ground, O2 sesnsor and frequency valve. As you have discovered, the frequency valve is plumbed into the control pressure circuit, and bleeds off pressure on this circuit. Lowering the pressure richens the mixture, which means the system can only richen a lean mixture. It cannot lean out the mixture if it is too rich. So you have to run the mixture lean for the lambda control to work.
     
  4. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    20,352
    socal
    can't you hot wire the FV so you can hear it click? If it does it is working. Then hook it up to a pressure line and hot wire it to see if it will flow fuel. Don't start a fire! With a good dvom you can test the o2 sensor as you heat it up with a propane torch. Well that's a start on some of the mechaniical items before you try dealing with the electrical ones. Also at smog stations they only sniff test at idle and 2800rpms. They do not test entire system function like the BAR ref when you go get the bar label on a euro car. They look to see what emissions are period. They are not looking for the perfect ideal lamda or stoichemetric A/F ratio.
     
  5. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi
    Light bulb !!

    Of course !! I have had the fuel distributor enhanced, so it is probably running to the rich side with the stock WUR control pressure setting. I can put the adustable control pressure 086 WUR back on and set it up for an overly lean control pressure, and let the freq valve/lambda control it to stoich, no? I would first like to confirm the operation of the existing equipment though. The lambda control is not an archaic "johnson box" it is a more modern Mercedes Benz unit (I can get model#s later if need be).

    Thanks for the input !!
     
  6. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi

    Good point. I can easily tune this, no matter what, to run stoichiometric to 2800 rpm. It's just driving it to the smog station without vaporizing piston crowns or burning valves !!! I think Motob is on to the program though. I'll test the O2 sensore for 0-5v with my Fluke VOM, and check the freq valve. Then I'll lean it out with the freq disconnected, and reconnect to confirm control (or some version of those things).

    Thanks for the input FBB !!

    More input welcome !! Anyone ??

    -Luigi
     
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  8. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,962
    The twilight zone
    Full Name:
    The Butcher
    I suspect you have just solved Lou's problem since he spent months trying to get the mixture richer
     
  9. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi
    Duh.


    (although, I never changed the control pressure on the stock WUR that was working along with the smog modifications prior to "the science project", it is back on as before, and system pressure has been dropped back to 84psi as well ??) I'll bet the 25% flow enhancment to the fuel distributor is the cause, and changing back to the adjustable 086 wur will nail it. There will be no boost enrichment, as there is no boost !! just a little vacuum/off idle control pressure change.

    -Lou
     
  10. Mark 328

    Mark 328 Formula Junior

    Nov 6, 2003
    510
    Orange, Ca
    Full Name:
    Mark Foley
    Lou:

    There is a Jetronic test procedure in the Tech Specs; service bullitin located here (page 134):

    http://ferrari.stevejenkins.com/books/328_tech.pdf

    If you pull the plug-off of you FI ECU you can run these tests outlined in the Tech Bulletin.
    It really does not take very long to do and it definitly will point you in the right direction.
    I'm not sure, but I think either the plug or the ECU is numbered.

    Mark
     
  11. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi
    Mine is all aftermarket conversion (graymarket Euro car). But I'll check it out for any usefull info anyway, thanks !
     
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  13. RVIDRCI

    RVIDRCI Formula 3

    Dec 1, 2005
    1,576
    Long Beach / Phoenix
    Full Name:
    Luigi
    Ok. No worries, all better now.

    Switched to the adjustable control pressure WUR, brought the control pressure up to almost match system pressure, adjusted the idle air fuel to a 14.7 +/- (warm) and voila !! the lambda system took control as designed.

    Thanks for all your input and ideas, boys !!

    Happy Thanksgiving !!
     

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