1-6 fuel distributor will not go lean | FerrariChat
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1-6 fuel distributor will not go lean

Discussion in 'Boxers/TR/M' started by Lavenknight, May 5, 2024.

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  1. Lavenknight

    Lavenknight Karting

    Jun 2, 2018
    79
    Chicago, Illinois
    Full Name:
    Alberto
    #1 Lavenknight, May 5, 2024
    I am having an issue with the 1-6 fuel distributor on my 85 US spec TR (engine family in picture). I am trying to adjust the fuel mixture on the distributor using the screw on the airflow meter (going CCW to lean) but no matter how lean I go the car will not respond. I can turn it CCW to infinity and it still will not respond or stall. The Idle remains steady. I turned off the car and pushed the airflow plate down and it did indeed adjust (goes lower before I feel resistance) so the screw is physically adjusting the plate. The car was at operating temperature when I attempted to make the adjustments.

    When I adjust the 7-12 distributor even a quarter turn the car starts to stumble. If I adjust another quarter turn it stalls.

    On the 1-6 distributor I removed one of the fuel lines on the distributor, jumped the fuel pump at the relay, pressed the airflow meter plate down, and slowly adjusted the screw until fuel started to flow Image Unavailable, Please Login out of the port so it does enrich. The fuel control and adjusted pressure are good at 5.4 and 5.0 PS. I am not sure why it won’t lean…. any thoughts?




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  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    34,413
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    #2 Rifledriver, May 5, 2024
    Balance the engine.That is a very typical response for an engine idling on one bank. Its very common.

    What are the current exhaust gas readings from each bank?
     
  3. Lavenknight

    Lavenknight Karting

    Jun 2, 2018
    79
    Chicago, Illinois
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    Alberto
    #3 Lavenknight, May 5, 2024
  4. Lavenknight

    Lavenknight Karting

    Jun 2, 2018
    79
    Chicago, Illinois
    Full Name:
    Alberto
    #4 Lavenknight, May 5, 2024
    1-6 is at 3.5% CO2 and 7-12 is at 2% CO2 at the tail pipe. O2 sensors disconnected.

    The vacuum (taken at the intakes) is 7.4 mmhg on 7-12 and 9.1 mmhg on 1-6

    When I balance the engine with screw #5 (starting base line was both screws on both sides half way down) and screw # 1….I can’t seem to get the throttle arm to rest/close on the microswitch on the TPS at idle position - throttle down when done with the adjustments.

    I jumped pin 18 and 2 at the TPS connection to simulate idle while making the adjustment but when done the throttle arm will not rest close on the microswitch at idle. Physically moving the TPS (it’s adjustable when you loosen the two screws) it doesn’t help the switch goes open but throttle arm is at idle position.

    I just can’t seem to balance it all to work. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login



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  5. Veedub00

    Veedub00 F1 Rookie
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    Jun 30, 2006
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    #5 Veedub00, May 5, 2024
    You have to follow the procedure for setting idle using the manual.

    you must, must use a manometer like in the manual. You can make one for ten bucks.

    you also need to use an external tachometer and do not use your gauge tach.

    I fiddled with this stuff for a very long time until a local testarossa owner and f chatter showed me how he set his idle with a manometer he made.

    I hooked my car up and set the balance in 15 minutes to perfection. I was amazed at using the correct tool made my struggles go away in minutes. I was floored.
     
  6. Veedub00

    Veedub00 F1 Rookie
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    #6 Veedub00, May 5, 2024
    turbo-joe likes this.

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  7. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    #7 Rifledriver, May 5, 2024
    CO is the least important gas coming out of the tail pipe. You have a screw to adjust it and can make it whatever you like. Its what the engine does with it that matters and that is what all the other gasses are about.
    A vacuum gauge is a manometer. Its all I use. Sorry but yours was wasted effort.

    But otherwise you are correct. This is being badly approached.
     
  8. Veedub00

    Veedub00 F1 Rookie
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    #8 Veedub00, May 5, 2024
    I used vacuum gauges, bought a different manometer, etc. For the hobby mechanic, the manometer is the cheapest and easiest solution. You tighten and loosen the adjustment screws and you get immediate feedback on magnitude and direction of both banks in one reading. The adjustments get very delicate as it gets evened out. Then you can gently adjust the vacuum until the rpm is exactly where it’s needed.

    the vacuum gauges I used weren’t sensitive enough to get an actual equal vacuum. With the manometer you know it’s exactly equal when the top of the column of (marvel mystery oil in my case) is equal.
     
  9. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
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    #9 tbakowsky, May 5, 2024
    You need to get fuel pressure gauges on this car. You also need to make sure you have ZERO vacuum leaks. Also make sure you are running on all 12 cylinders. You seem to be running on 6 cylinders by your description.
     
    Rifledriver and turbo-joe like this.
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    #10 Steve Magnusson, May 5, 2024
    Last edited: May 5, 2024
    This is good, but it's important that the range of adjustment is such that when you are running the fuel pump and you adjust the mixture screw CCW, that this point of resistance can be made to occur when the airflow plate metering plate is further down lower in the funnel than its "normal" idle position -- can you do this? If you can't, it would be an indication that the Plunger's rest position is not correct. Alternatively, you could compare where the airflow plate is in the funnel on the working 7/12 bank when the airflow plate is at the point of resistance vs where it is on the 1/6 at the point of resistance -- they don't necessarily need to be exactly the same but they should be in the same ballpark and not drastically different.

    You didn't give any background information. Were these fuel distributors working perfectly fine before, untouched, and you are just reinstalling them, or were they completely disassembled and rebuilt?
     
  11. Lavenknight

    Lavenknight Karting

    Jun 2, 2018
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    Alberto
    #11 Lavenknight, May 6, 2024
    That’s a good point. This upcoming weekend I will try to get the plates as close as possible to each other using a digital caliper measured at the point of resistance from the top of the distributors. From there I will attempt to balance them again per the workshop manual. I used 2 digital manometers to measure the vacuum. One on each bank.

    I purchased the car 2 years ago and have been slowly working on it. It wasn’t running when I got it due to many issues……mainly neglect in maintenance and most likely sitting for a long time (not good). It runs a lot better now after I completed a major on it last year but it’s down on power due to this issue which appears to be from what we are discussing a balancing issue…..or so I hope. I will report back this weekend thanks for everyone’s help so far.


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  12. tbakowsky

    tbakowsky F1 World Champ
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    #12 tbakowsky, May 6, 2024
    Please confirm spark on both banks before going further.
     
    turbo-joe likes this.

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