412 Intermittent Loss of Power | FerrariChat

412 Intermittent Loss of Power

Discussion in '365 GT4 2+2/400/412' started by Kurt SC, Aug 31, 2017.

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  1. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    Hey all. I've had my 412 for about 2 months and she ran superbly for her first 300 miles. On mile 301 I started noticing intermittent hesitation during acceleration and deceleration. What was so slight and only lasted 2 or 3 seconds at first had turned into an 80% loss of power for 3-5 minutes at a time. Hence broke down and limping on the side of highway. Car does stay started with rough idle though. Over the course of 20 minutes of driving, the car looses power 3 or 4 times lasting for several minutes and then suddenly regains total power and drives fine.

    I replaced all 12 spark plugs with new and properly gapped - made no difference
    I also replaced 20 relays under passenger foot and 7 relays in glove box with new - made no difference.

    I ordered a smoke machine to check for vacuum leaks but it isn't here yet.

    I welcome any comments or advice on to where to check next.

    Kurt
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Has your 412 been "converted" to US emissions? I.e, does it have a frequency valve added into the CIS control pressure plumbing and an ECU added to run it?
     
  3. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    There's no California emissions stickers anywhere. other than that how does one tell?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
  5. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    #5 Kurt SC, Aug 31, 2017
    Last edited by a moderator: Sep 7, 2017
  6. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    #6 Kurt SC, Aug 31, 2017
    Last edited by a moderator: Sep 7, 2017
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Yes, the thing with the yellow plastic with the grey harness connector with the two (non-stock) wires is an added frequency valve (FV). First, thing to do is confirm/deny if it vibrates (by touching it) when the engine runs well, and confirm/deny if it vibrates when the engine runs poorly. If the system is still actually working (i.e., the added ECU is present and working) the FV should be vibrating whenever the engine is running. If it does vibrate during good running, but doesn't vibrate during poor running = you need to confirm if the added ECU is getting +12V power during good running, but not getting +12V power during poor running (after you find it ;)).
     
  8. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    I'll check that. I was wondering why the valve looked rigged with two gangly wires. Great to know info. I'll report back. Thanks so much!
     
  9. blkprlz

    blkprlz Formula 3

    Mar 24, 2007
    2,169
    Tampa bay
    Full Name:
    Bruce
    I noticed that Kurt's WUR's aren't connected to each other as the earlier 400i's, was this link discontinued when the 12 cylinders began using FV's?
     
  10. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,723
    Amsterdam
    Sounds like one bank is losing spark or fuel pressure. Very likely electrical fault by oxidation in a connector somewhere. If you get a smell of fuel at the back if it occurs, look for a spark problem. Imho fuel problem is slightly more likely. If you get a smell of fuel at the back if it occurs, look for a spark problem.
    If the problem is in the ignition system then be careful, because of the fuel mixture buildup in the exhaust and back during a no-spark situation, you would not be the first to blow your exhaust system to bits with an errant ignition system going on and off on you. Ask me how I know.
     
  11. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
  12. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    #12 Kurt SC, Aug 31, 2017
    Last edited: Aug 31, 2017
    ***New discovery I was just feeling for vibration of the frequency valves when I smelled burning. The first stage of the driver side muffler was glowing red hot and smoldering the top metal. Passenger side was not glowing. Is it possible that the muffler is clogged? The first stages connected to exhaust manifold are the only original parts of muffler. The other sections have been replaced. Heat = restriction= loss of power? Car only had 300 miles put on it in a ten year period. Also small rust particles ejected from tailpipe too
     
  13. 57Wayne

    57Wayne Karting

    Mar 29, 2015
    127
    Wilbraham MA
    Full Name:
    Wayne Thresher
    On my 412 those first 'mufflers' after the headers are the catalytic converters. Prior owner had the passenger side one gutted. I replaced both with units from Summit.
    Paid a shop to put them in.

    Sent from my Moto G (4) using Tapatalk
     
  14. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #14 Steve Magnusson, Aug 31, 2017
    Last edited: Aug 31, 2017
    No, a restriction can't cause overheating.

    +1 - If you've lost spark, as 166&456 suggested, and have cats, the fuel/air mixture will ignite inside the cat. However, losing a bank of spark wouldn't cause rough running -- just weak, smooth running. Similarly, if the Air-Fuel ratio is whack-o, that can also dump unignited mixture into the cat that will ignite there and overheat it, and that condition can have rough running. So, OP:

    1. Which is it? Rough bad running or weak smooth running.

    2. When the cat was overheating, was the engine running well+smoothly, weak+smoothly, or poor+roughly?
     
  15. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    If you get no where on the spark side of things, have a look at the fuel pump system. Another owner on here had a 400 with power hesitation problems and ended up being lack of fuel pressure.
    As your setup is similar with 2 fuel pumps, they have non return and check valves fitted to both, so 1 pump can be working and pumping some fuel to the k tronic and the rest flows back into the tank via the other pump.
    Hence you get fuel starvation.
    1. Check both pumps actually running
    2. Disconnect 1 pump and break pipe on other pump and check its output- do the same with other pump.
    3. Disconnect suction of 1 pump, also disconnect its electrics and run other pump- if non return valve is working you should get no fuel out of disconnected suctiom pipe.
    4. Repeat above on other pump.
    5. Assuming you prove both pumps- i understand it is possable to fit a pressure gauge on the k tronic in the engine bay to prove the fuel pressue, exactly where i am not sure.
     
  16. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    #16 Kurt SC, Sep 1, 2017
    Last edited by a moderator: Sep 7, 2017
    Is the pic a cat or muffler? To answer Steve's questions:

    1) the engine idles rough. It usually idles right at 1,000 rpm's but during the fit, idles rough and below 900. Engine is noticeably shaking.

    2) When the cat overheated, the engine was at idle running poor and rough.
    Image Unavailable, Please Login
     
  17. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    Looks like a cat to me (but not sure), and would be consistent with adding the FV and O2 sensor.

    Since "rough", I'd lean away from just losing a bank, but easy enough to confirm/deny spark on both banks and that both fuel pumps are operating just to be sure.

    "Rough and not able to rev up" would be a strong sign that the added "Lambda"(FV) part of the system is not working -- can it rev up when it's idling badly?
     
  18. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    Steve: When it runs rough during idle and I rev it up, it does rev but seems way less responsive and less powerful, seems delayed.
     
  19. Kurt SC

    Kurt SC Rookie

    May 16, 2017
    32
    Charleston
    Full Name:
    Kurt W.
    Steve: I know what a vibrating electro valve should feel like if it were to get power. When I felt the (FV) for vibrations before the cat smoke checked, I could not feel any vibrations for when the engine ran smooth or poor. Is the added ecu under the passenger foot on top of the main electrical panel? I can send a pic.
     
  20. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    This is always possible. If the system was tweaked up AFTER something in the FV+ECU had failed, it would just run as a K-Jet without Lambda system again. Another way you could confirm/deny if the "with Lambda" modification is still doing anything would be to measure the DC voltage on the single signal wire of the O2 sensor relative to ground at warm idle with the O2 sensor both plugged in and not plugged in. If the wandering of the voltage is about the same = it's dead. The wandering of the O2 sensor voltage should be larger at warm idle if it is really doing something. If it is already (and always) dead, you'll have to look elsewhere for your fault.

    Probably ;) Please do post a pic if possible. Have seen both Bosch and aftermarket (DC Johnson brand IIRC) ECUs added here, so always glad to see another one, or something else, just to add to the mental data base.
     
  21. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    2,028
    Barrington, Ill. USA
    Full Name:
    Ross
    I'll bet you are losing spark. Any backfiring? The raw fuel being dumped into the cats would account for them glowing hot, which means they are probably ruined.
    Could be fuel pressure too low for proper atomization but my money is on an electrical (ignition) fault as it's intermittent.
    Good luck
     
  22. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    Have you noticed any increase in the sump oil level or does the dip stick smell of fuel ?
     
  23. Part Time

    Part Time Formula Junior
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    #23 Part Time, Sep 3, 2017
    Last edited by a moderator: Sep 7, 2017
  24. Part Time

    Part Time Formula Junior
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    #24 Part Time, Sep 3, 2017
    Last edited by a moderator: Sep 7, 2017
  25. Part Time

    Part Time Formula Junior
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    #25 Part Time, Sep 3, 2017
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