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Injection calibration and service

Discussion in '365 GT4 2+2/400/412' started by sebackman, May 28, 2019.

  1. sebackman

    sebackman Karting

    May 19, 2010
    62
    Dear all,

    I just got my 400i injection system calibrated and a broken warm-up unit re-built by Geert Jan at "http://www.ferrari400parts.com/" . Super service and very friendly so I thought I'd share here.

    Best regards

    //Rob

    1980 Ferrari 400i Spyder (Straman)
     
  2. Schumi

    Schumi Formula Junior
    Owner

    Jun 5, 2002
    703
    Missouri
    Full Name:
    Daren
    Aside from the warm-up regulator, what symptoms were you experiencing that caused you to need this calibration/service?
     
  3. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,247
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Rob, What is meant by calibration? Do you just mean adjusting the %CO at idle? What else is involved.
    Ken
     
  4. raemin

    raemin Formula Junior

    Jan 16, 2007
    426
    Lyon (FR)
    Full Name:
    R. Emin
    Once the k-jet is calibrated all you have to do is adjust the CO & idle speed and the whole system should be working perfectly. System pressure should be checked under hot/cold/WOT conditions, and what is the most important for the engine : all the injectors should spray the same amount of fuel, as you do not want one cylinder to be lean. If the system is not perfectly balanced you can make it do with a slightly rich adjustment, but having an injected car that pollutes and smells like carbs sounds like the worst of both worlds...

    As a side note on the k-jet, the CO is adjusted on the whole range (not only idle), and unless the car has the nipples on the conveyor (or a cone shaped disc sensor), the engine is supposed to be slightly lean at mid throttle. As a personnal choice I do prefer to have it slightly rich at idle in order not to "starve" the engine at mid throttle (slightly rich at idle, normal at mid throttle, slightly rich at WOT instead of normal/lean/normal). Also as we are adjusting the whole curve, we can tune the car for fuel blend of "lesser" quality (as long as the refurbishing kit is compatible with ethanol blends).
     
  5. sebackman

    sebackman Karting

    May 19, 2010
    62
    Hi,

    Just as raemin points out there are several adjustments in the actual fuel distributors and the warm-up regulators that can cause odd behaviour. The Bosch system is entirely pressure driven and if the control pressures are off it is difficult to get them running well. Now I know that my units are well in spec.

    With the corrects pressures the only thing to worry about is CO/HC and idling. Both processes are well described in the work shop manual. I have a 4-gas analyser for the CO and have built a simple syncro device with a vacuum gauge to set idling on both banks.

    As raemin, I also set the CO to as high as the legal requirements alow me at idle. That will be a bit rich at low RPM's but fine at higher RPM's.

    Mine did run uneven on the right bank due to a faulty warm-up regulator. That is probably normal after 40 years and I think the high level of Ethanol in the fuel over here does not help in these cars that normally are driven sparsely.

    I will also remove and clean the injectors to make certain they are fine. I did exchange them for new ones a few years ago. They are the same Bosch units (exactly the same Bosch part number) as in some Mercedes models of the time and the ones via the Mercedes spare parts chains are significantly cheaper…

    I also had a problem with hot fuel returning to the tank in the amount that they eventually got warm with the effect that the left bank started cutting out. I hope that may be cured now. After some hours driving the tanks got up to about 50 degrees Celsius on a warm day. Not good.

    I have not put back all the bits yet, but that is what weekends are for . I will revert back with feedback once in place and started.


    Kind regards

    //Rob
     

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