cold start problem - need help! | Page 2 | FerrariChat

cold start problem - need help!

Discussion in 'Boxers/TR/M' started by jkg2101, Dec 29, 2024.

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  1. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Not if the cooling system is cold and closed, and you are quick about it. Just put a rag under the y-pipe to catch any small amount that might come out during the switch over.

    Yes. It's been updated so the part number will end in .02 (instead of .00) IIRC. It serves the same "protection" function on an abs system -- it protects the ECU from the alternator going haywire.
     
  2. theunissenguido

    theunissenguido F1 Rookie
    Owner Silver Subscribed

    Jan 21, 2004
    2,646
    Argent/Brasil
    Full Name:
    Guido
    You can also open that faulty relais to see what is wrong...maybe just a spring that broke or jumped of his connection.
     
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  3. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,007
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    The harness connectors at both thermo switches have a very hard bend in them. They are famous for fracturing the wire at that bend, especially during a service. I repair them regularly.
    Then we have the infamous C12 connector.
     
  4. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I took apart the protection relay. It comes apart by popping off the top of the fuse holder, and then sliding out to the other part of the fuse holder, and then the whole metal lid comes right off. The thing that was rattling around inside was simply a small sheet of insulating material. I don’t think there’s anything defective in that. The relay looks fine to my eyes except on the printed circuit board there looks like there is some rust or corrosion or burning at a couple of solder points.
     
  5. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I’m hoping that the new relay I ordered will fix this problem. The connector that attaches to this relay box, the smaller one, doesn’t lock in very securely, although otherwise it looks OK. The larger connector looks like it locks in nice and tight. I see where the wires to the thermal switches take a sharp angle. The wires are covered with a rubber sleeve so it’s hard to really get a sense if they’re broken, but they certainly do take a sharp turn
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  6. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    update (and further advice appreciated)
    the old protection relay had infinite resistance across its "coil" wires, so i think it is defective
    i just received the new relay in the mail and it measures a few ohms across the same terminals, so it seems good
    i popped the new protection relay into the car, and it started MUCH easier, but then while warming up, it often surged from 800 to 1500 rpm. when it warmed up, it was better, but still some surging and easier to stall. it idles at 1500 rpm, which is because the main brass bolts on the throttle bodies are open too far, but if i close them down, it doesnt want to start (Also the thermal time switch is still broken)
    I did not run it much.
    I guess this confirms that i need to get the basic tune set up from scratch. I plan to remove the entire air filter housing. which will leave the large vacuum hose at the front of the housing temporarily open to air. I also plan to use the 2 small vacuum lines at the back of the intake plenums to attach my vacuum gauge. i am embarassed that I dont know what these lines are for, but I am hoping leaving the lines disconnected will not be important during initial set up
     
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    +1 -- Now that you've got the EHAs working, the minimum is that the warm idle mixtures (O2 sensors unplugged) will need to be retweaked, but never hurts to confirm that the two banks are balanced/equal both when the air bypass screws are fully closed (warm idle RPM = ~700 RPM) and when the air bypass screws are opened the correct amount (warm idle RPM = ~1000 RPM)

    Not a problem at all -- that is just the crankcase ventilation hose (and is upstream of the throttle bodies).

    Those small vacuum lines go to the charcoal canisters (to dry out the charcoal beds during engine running). Fine to use those fittings as a place to connect your vacuum gauge(s) to measure the intake plenum vacuum levels (and leave those hoses off).
     
  8. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    thanks steve. makes sense. i just posted another thread where i am seeing some water in the crankcase vent hose. i wonder if that is a big problem
     
  9. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I am in the middle of trying to set this up. The throttle micro switch plug has three connectors. Which are the two? I am supposed to bridge across when it’s disconnected?
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    You should always first try searching on the F part number that you have a question about for prior threads -- in this case "121517".

    (But since I'm here) The #2 terminal in the harness connector should be connected to the #18 terminal in the harness connector to simulate a closed idle throttle microswitch at idle:
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  11. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    thanksi tried searching with text and couldnt find it

    now i have a new question - challenge
    i am trying to set up idle and mixture from scratch
    If i turn the large brass bolts (air injection bolts I think) all the way in, the car will stall - so i turned in the throttle position screws to get the idle up to almost 1500 rpm. i can not get the car to idle less than 1500 rpm on the dash tach. if i turn the throttle position screws out any further, the engine starts surging and then stalls. at the 1500 rpm idle, I have good balance between the 2 sides of the engine based on my vacuum gauge, and i have adjusted the linkage bars so that both throttle position screws are synchronised properly. If i turn out the large brass air injector bolts, i can raise the rpm and keep the vacuum balance nice and even
    if i check voltage on the O2 sensors, i am getting about 0.8 volts, which is a little rich but shouldnt be a problem

    i understand the dash tach might be off, but not this far off. anything obvious I am doing wrong? it just doesnt make sense to me. if I bring the idle down it just starts surging and then will stall. the surging gets worse on its own

    opening the large brass air injection bolts even a little bit brings the rpm's up a lot.
     
  12. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    i admit that i did not have the throttle microswitch disconnected properly while doing the adjustments...
     
  13. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    That's probably the problem -- when the idle microswitch is open, the ignition timing is advanced by the Microplex ignition ECU, and the engine RPM will increase. This is the final test you should do -- when it's warm idling at ~1000 RPM and you think everything is good, unplug the throttle microswitch = the engine idle RPM should increase and then decrease when you plug it back in.

    My dash tach read about 1150 RPM when the true engine speed was 1000 RPM.
     
  14. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I bridged across the micro switch terminals the way I was supposed to, and it didn’t seem to make a difference in the ability to title the engine. It idles at 1500 on the dash tack and it does sound like it’s racing a little bit
     
  15. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    When I unplug the bridging wire connector on the micro switch, the RPM definitely does raise up the way it’s supposed to
     
  16. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I only need to turn the large brass injector bolts out maybe 1/4 of a turn. More than that and it feels like it’s really racing too much.
     
  17. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #42 Steve Magnusson, Jan 4, 2025
    Last edited: Jan 4, 2025
    This is good (as it also confirms that the Protection Relay system is working as the throttle microswitch system uses the same +12V signal from the Protection Relay). However, you still need it to idle below 1000 RPM when the air bypass screws are fully closed. Are you sure something mechanical isn't hanging the throttle plate mechanism(s) open or you have a vacuum leak somewhere?
     
  18. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    i've been studying the injection system trying to figure out what is wrong.
    from what i can tell, once the throttle bodies are synchronized, the linkage bar binds them, so that any adjustment to either throttle position screw will move both throttle blades together. so once the linkage bar is set in place, really the only thing i am tuning is the baseline opening of the throttle blades for idle
    if I try to turn those screws out, to decrease the idle, the car begins surging (rpms will drop low, then surge up high, then go lower, then go higher, then eventually stall). I can stop this process by rotating the linkage bar to open both throttle bodies (or by pressing the gas pedal - same thing)
    i assume the surging is the computers somehow trying to prevent stalling? maybe that is wrong. it is doing this whether the O2 sensors are plugged in or not.

    a vacuum leak is an interesting thought - would that cause the idle to be too high, and then it wants to stall if the throttle blades get closed too far? i dont see any obvious sources for a vacuum leak.
     
  19. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    You can disconnect the bar between the two throttle bodies to ensure that both throttle plates are contacting their respective adjustment screws and are able to follow them down to a very closed position (or not).
     
  20. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    If the fuel mixture was too lean, would that cause the engine to start surging up and down and then stall if I tried to close down the throttle blades?
     
  21. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    It is a "circular" process where you may need to do some airflow adjustments, readjust mixtures, do some airflow readjustments, readjust mixtures, etc. until all the desired conditions are met.
     
  22. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    I spent another hour with the car and am ready to pull my hair out. This time, i ventured into the mixture screws. I used a voltmeter on the O2 sensor plug, although I am not sure I can trust my voltmeter. If i turn the mixture screw about a half turn either way, the engine will run more poorly, so I have it at the sweet spot for both. The O2 sensor voltage is at 0.8V. i can get it to go as high as 1.0, and once i got it to go to 0.5v, but the voltage reading often reads 0.8v even if I move the mixture screw, so I dont know that i can trust my voltmeter reading.

    the problem is completely unchanging - i need to open the throttle blades on both throttle bodies to get the rpm to about 1400 - if I close the blades down any lower, then it begins surging/oscillating rpms up and down, and will stall after a few cycles. i can cheat by opening the air bypass bolts a bit, but can not get the idle down any lower.

    i am completely and literally "Exhausted" by standing in the exhaust stream for the past hour. I should not have bought a car from across the country - never again!
     
  23. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,709
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Half turn is a HUGE mixture adjustment. If you can't manually "swing" the O2 sensor single wire output from 0.1~0.2V (lean) to 0.8~0.9V (rich) at warm idle with the O2 sensor single wire unplugged with the mixture screw on each bank = you have some other problem.
     
  24. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    19,914
    The Cold North
    Full Name:
    Tom
    Check for vacuum leaks from the braided hose that comes from the air valve up to where the cold start injector is attached to the upper plenum. These never seem to get checked or changed. Have found a few that are cracked and have become porous causing a vacuum leak. I would suggest to replace those hoses regarless.
     
  25. jkg2101

    jkg2101 Karting

    Jan 25, 2015
    176
    New York
    thanks for the thoughts on those hoses from the auxiliary air valve.
    i thought it odd that the voltage reading of the O2 sensors was not as predictable as I thought.
    The mechanic across country who did the engine work said he thought the mixture screws might need a full turn in, to increase richness, given the behavior of engine, and how he set it up presumably with the protection relay not working.

    i also checked the diaphragms (sensory plates) and they seem to be in perfect position. Both the auxiliary air valves are closed when the engine is warm.

    If am I not swinging the O2 sensor outputs by rotating the mixture screws, i don't know where to go next. I wish someone made a handbook for diagnosis and repair. maybe one of our experts should do it. i would buy it! the WSM doesnt give enough info,

    I think i will rig up a better way to check O2 sensor voltage, other than me trying to hold the voltmeter probe while simultaneously plugging the hole on top of the mixture screw

    If all else fails, i can take it to a ferrari specialist a few hours from my home. I will have to prepare for the usual in that case - since this is a "family channel," i will keep it clean, but let's just say i will bring some Vaseline and be prepared to take one for the team.
     

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