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1981 308 GTSi, no power

Discussion in 'Technical Q&A' started by Sickly308GTSi, Oct 18, 2018.

  1. Sickly308GTSi

    Sickly308GTSi Rookie

    Oct 10, 2018
    16
    Full Name:
    Mark Collins
    Good evening,

    I posted about this car the other day. We had a lot of great feedback from you great folks, and there was a lot of dialogue. While we did make some progress on the car's condition, we're still lacking power badly. I wanted to post again, corralling the information that we have gained in hopes that filtering some of the white noise and providing some good information to you folks will help someone spot the issue immediately and we can finally get this car going tomorrow. It's always that easy, right?

    We have a 2V euro spec that was converted to a US spec. It idles well, and responds to rev-ing MOSTLY well, up to 3,000 RPMs. It absolutely will not go over 3,000 RPMs. To move the vehicle with its' own power, you have to rev it up over 2,000 RPMs and quickly/carefully clutch out. Correctly executing this delicate dance will only net you enough power to get it in and out of the garage.

    We have spent a lot of time getting to know this vehicle. We know that we have good system pressure, between 75 & 80 PSI. We have a control pressure of 50 PSI. We have all new injectors. We have new plugs. Cap and rotor are in good shape. We haven't yet ohm-ed out the wires, but we have looked at the fire from each wire and its a strong, consistent blue arc. We've watched each coil at idle and under rev, both maintain and do not seem to break down under a load. We have verified and confirmed (with a light on the flywheel) that the timing is correct and advancing/retarding as it should. We did check the timing on both #1 and #5 cylinders. We have good compression, as follows. These numbers were obtained while cranking with all plugs removed.
    1-185
    2-180
    3-175
    4-180
    5-195
    6-200
    7-195
    8-190

    I took a video of where we're at. Any help is greatly appreciated!

     
  2. MerlinTech

    MerlinTech Formula Junior
    Sponsor

    Mar 5, 2010
    454
    Georgia
    Full Name:
    Wade Williams
    Just my shot in the dark. I suspect you are not getting fuel through the metering unit (fuel distributor) to the injectors. Bosch had a tool that you could plug each injector into while attached to the car and activate the system and watch them. Without that, I would try using something like brake cleaner to spray into the intake as it struggles and see if it picks up. If it does, you need more fuel and that is the fuel distributor. Looks like you covered everything except lean condition.
     
  3. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,626
    Texas
    Full Name:
    Steve Magnusson
    #3 Steve Magnusson, Oct 18, 2018
    Last edited: Oct 18, 2018
    Have you "unconverted" it, or does it still have an added frequency valve in the control pressure circuit?

    Are you saying that at warm idle you are able to adjust the mixture from lean to rich and set it to a reasonable value?

    Also, the mechanical check of smooth FD plunger motion (i.e., deflection and return of the airflow metering plate) at zero supply fuel pressure is OK?
     
  4. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,722
    Midwest
    Full Name:
    Brian
    If I had it, I would go back to square one......

    Mechanicals, cam timing, then electrics like the ground points especially on the ignition boxes, then fuel, I like Steves post, more info would help
     
  5. slewman

    slewman Karting

    May 4, 2004
    154
     
  6. slewman

    slewman Karting

    May 4, 2004
    154
    Check the exhaust system for a restriction
     
  7. Sickly308GTSi

    Sickly308GTSi Rookie

    Oct 10, 2018
    16
    Full Name:
    Mark Collins
    I owe you one big ass beer. You got the suggestion of the century. My father-in-law dropped the exhaust and it immediately revved and redlined as it should. Bad cat. Thank you very much for the suggestion!
     
    TonyMorristown, ken qv and f355spider like this.
  8. Jdubbya

    Jdubbya F1 World Champ
    Silver Subscribed

    Dec 28, 2003
    19,777
    PNW
    Full Name:
    John
    Cool! That was gonna be my suggestion too since you covered everything else and I don't know the injection system at all.
     

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