Mondial 3.2 K-Jet and O2 Sensor Control System | FerrariChat
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Mondial 3.2 K-Jet and O2 Sensor Control System

Discussion in 'Technical Q&A' started by Wade, Jan 27, 2015.

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  1. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
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    Wade O.
    #1 Wade, Jan 27, 2015
    Last edited by a moderator: Sep 7, 2017
    First I should say that my grey market Saudi Arabian (SA) spec Mondial is running pretty awesome.

    Plus, when cold it jumps to life at the first turn of the key, without throttle input. When warm or hot, it'll start on the second crank or with a little gas pedal action during the first. Not too bad really but it could be better.

    However, during a recent drive I noticed the HVAC internal doors were moving when I'd accelerate without downshifting. So I'm assuming a vacuum leak somewhere, which could be tied to the warm start "issue".

    So looking around, I notice that some things aren't where they should be, and/or outright missing as well. Needless to say, I'm still investigating...

    BTW, the frequency valve, it's not working. And it doesn't have a dampener companion either.

    Two photos are examples of the US and Euro (thanks Steve) compared to mine (the one with the closer view).
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  2. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
    Full Name:
    Wade O.
    #2 Wade, Jan 27, 2015
    Last edited by a moderator: Sep 7, 2017
    So I go looking for the protection relay and it ain't there either.

    Actually, there's nothing in the aft compartment except a Mercedes Jetronic ECU (Bosch 0 280 800 038). My guess, at this point, the extra wire goes to the O2 sensor.

    So I'm looking at two opportunities; return to SA stock which means removal of the Cat (smelly exhaust) or try to reactivate the frequency valve.
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  3. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
    Full Name:
    Wade O.
    #3 Wade, Jan 27, 2015
    Last edited by a moderator: Sep 7, 2017
  4. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
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    Wade O.
    #4 Wade, Jan 27, 2015
    So to clarify:

    I need to fix a vacuum(?) leak so that the HAVC system directs the airflow properly.

    Is the frequency valve really effective as configured (when working of course)?
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    #5 Steve Magnusson, Jan 27, 2015
    Yes, it's OK/typical for the modification that you have -- it adds a frequency valve to change the control pressure (and the system responds relatively slowly to changes in control pressure) so no damper is used (on the stock US version K-Jet with Lambda, the frequency valve changes the lower chamber pressure -- and that has a much faster response -- so needs the damper).

    You don't necessarily need the Lambda system working to keep using cat(s). '80-'83 US 308/Mondial are K-Jet without Lambda but with cats. But no harm getting the quasi-Lambda part to work if you can. The protection relay is a safety device (to prevent a haywire alternator from blowing up the Jetronic ECU) -- would be best to have one.
     
  6. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    #6 Wade, Jan 28, 2015
    Last edited by a moderator: Sep 7, 2017
  7. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    #7 Wade, Jan 28, 2015
    What's interesting is that, many times (from what I've read), starting/idling and drivability issues are attributed to inoperative frequency valves (often caused by a faulty protection relay/fuse?). I don't seem to have any of those problems even though my FV isn't working.
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Jan 28, 2015
    That's very true on the US "with Lambda" CIS cars IF the mixture has been set with a working frequency valve and then the frequency valve stop working for an electrical reason. However, if the mixture has been set when the frequency valve is not working = that runs OKish (but some cold starting/cold running features won't work so well). Since your car is running OKish with a non-working frequency valve, it's safe to assume that the mixture was set with a non-working frequency valve. Unfortunately, many US "with Lambda" cars are (wrongly) "fixed" by making a mixture adjustment when the real problem was/is the protection relay/frequency valve operation has failed.

    Likewise, if the mixture was set with a non-working frequency valve, and then you restore the frequency valve operation = the mixture screw will probably need to be reset (when the frequency valve is now working).
     
  9. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
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    #9 Wade, Jan 28, 2015
    Last edited: Jan 28, 2015
    Apparently I need to trace my wires and components. For example, I thought that the "extra" wire coming out of the ECU might lead to the O2 sensor (green wire in post #2). Well, probably not since it reads just under 4 volts whether the car is cold or hot.

    Some exploratory surgery is in order...
     
  10. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    East Central, FL
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    #10 Wade, Jan 30, 2015
    Last edited by a moderator: Sep 7, 2017
    Three wires from the O2 sensor; two are heater and one for sensing:

    "Unplug the O2 sensor and tap into the wire that sends the mixture signal, on single wire O2 sensors no problem, on sensors with three wires two are for the heater and the other is the signal. I can't remember which one is the signal so just try each one until you get a small voltage."
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  11. 85QVEuro

    85QVEuro Formula Junior

    Jan 15, 2021
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    #11 85QVEuro, May 12, 2022
    Steve - I have an 85 Mondial euro that was imported to the US in August 85 when it was federalized. Based on the fact that there are no cats and other emissions add on items for the US, I suspect that the shop that did the conversion did just enough to have pictures to get it approved for registration in the US. I just had my CIS renewed by CIS Flowtech and as I dig in deeper, I see that I have a frequency valve but there are no electrical connections going to it (see photo below).

    Can I simply eliminate the frequency valve, use two shorter (single) banjo bolts and adjust the mixture for this set up? Thanks for taking a look...

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  12. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #12 Steve Magnusson, May 12, 2022
    Yes, you can remove that added FV and hoses. With no electrical signal going to it, it would just be closed all the time so should have no effect if you remove it and its hoses (if the car was tweaked-up with it disconnected).

    Do you still have a Vacuum Limiting Valve (aka Bypass Valve) in place? Item 77 here:

    https://www.ferrariparts.co.uk/diagram/ferrari/mondial-qv-coupe-cabriolet/011-fuel-injection-system-fuel-distributors--line

    (Just curious about what they modified in the "federalization".)
     
  13. 85QVEuro

    85QVEuro Formula Junior

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    #13 85QVEuro, May 12, 2022
    Good question - I do not have the vacuum limiting valve - My suspicion is that the shop that federalized the car did some cursory changes and probably photographed them for submission with the application to the EPA or whoever. At this point, I'm actually happy that the car is more euro than converted so I will get some shorter banjo bolts and eliminate the frequency valve (also saves me the trouble of getting the 7.5mm high pressure hose for the FV - BelMetric is out of it).

    Steve - thank you for your help with this and the other questions I have posted since I started this project last year
     

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