persistent starting problems 400i, #48739 | FerrariChat

persistent starting problems 400i, #48739

Discussion in '365 GT4 2+2/400/412' started by moserpe, Oct 6, 2016.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    First time it happened 2 years ago: after the car was parked for about 2 hours following a longer drive, the engine did not start as usual. Only after several attempts it started to fire with a couple of cylinders only and then gradually up to all twelve when i reved it up. This problem did not repeat for some time. The engine started as usual under any (cold/warm/hot) condition. Then suddenly it happened again: immediately after stopping the engine it was not possible to restart it. A check of the ignition revealed that it did not develop sparks at the spark plugs but at the coil only. The mechanic of the road assistance suspected a problem with the primary ignition cable (from coil to distributor cap) although all cables had been renewed recently. After putting this cable back, the engine started to fire as described above beginning with single cylinders.
    This pattern developed worse and worse even with a new primary ignition cable, the engine started in cold condition only. Sometimes it could help to boost the battery with the help of another car, which increased obviously the system primary voltage and the starting revs.
    So far i was convinced that it was an ignition problem because the whole injection system (except the thermal time switch) is independent for the left and right cylinder banks what means that the failure of any component would influence six cylinders only. Therefore i investigated more deeply in the electrical system and found and remedied a resistance in the main battery connection (12 Volts+). This seemed to solve the problem since the car could be started regardless of temperature conditions. However after a long drive and a half hour stop it was all back to step one. I removed the distributor cap and found it cracked, which seemed to be a good explanation for the problem. I fitted a brand new cap and rotary arm, now convinced to have no further starting troubles. Surprise: the situation remained unchanged. The engine now and then refuses to start when hot. It is not systematical however which means that sometimes it works flawlessly with a trend of getting worse over the time. Since it now develops sufficient sparks at the spark plugs, i do no longer suspect an ignition failure.
    I have now systematically checked the K-Jetronic and could not detect any anomaly: pumps, warm-up regulator, mixture control unit, fuel distributor are in excellent condition. In a next step i will check the thermal time switch circuit which is the only device which influences directly both cylinder banks.
    Since i do own the car, it always showed an idle problem during the warm-up phase. After the auxiliary air valves are closing, the engine starts to "hunt" (oscillating revs) until reaching steady operating temperature. During this phase it would even stop without keeping it running by the accelerator. It is very annoying when the car must be manoeuvred (automatic transmission) before warmed up completely.
    Did any of the owners of 400i / 412 have similar symptoms with their cars? Any ideas how to solve it?
     
  2. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    #2 mike32, Oct 6, 2016
    Last edited: Oct 6, 2016
    Dont know anything about your model but this has all the signs of the fuel vapourising in the fuel lines, do you have an accumulator fitted just after the fuel pump, if so try renewing it. I think the k tronic system also has a pressure regulating unit which may be worth a look.
    It explains why it struggles to start as the fuel is more like a vapour until you get the engine running and the vapour is replaced by cold fresh fuel .
    I had a look on diagram and you have 2 accumulators, item 33
     
  3. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    The system has indeed two pressure accumulators and two pressure regulating valves. I can exclude the pressure regulating valves because once started, the system operates properly which would not be the case if the system pressure was not correct. The emissions are well below the legal limits (hot engine). The accumulators could actually cause the problem, provided that they both are not working correctly because otherwise one cylinder bank should fire.
     
  4. Al Campbell

    Al Campbell Formula Junior
    Owner Silver Subscribed

    Nov 22, 2013
    571
    Australia
    The hunting problems & stalling when cold are not normal. Once started the car should be drivable straight away (do not rev it too hard until it reaches operating temp though). There are many things that could cause these sort of problems. The fuel distributors may be sticking or have perished diaphragms. The fuel injectors may not be holding pressure & leaking when the engine is switched off causing too much fuel to enter some cylinders flooding them & causing starting issues - especially if it clears & comes good after a few revs when starting. I would start by replacing the fuel injectors or having the old ones cleaned/tested.

    Cheers,
    Al
     
  5. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    Assuming same as the mondial, they are no good if there is fuel at the tell tale hole in the back of the accumulator. I assume you have 2 different fuel lines coming to the distributor where they must go 2 into 1 ?
    I have seen a picture on here where a pressure gauge was fitted into the top of the fuel distributor, might give you some usefull info ?
     
  6. Newman

    Newman F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 26, 2001
    14,093
    Canada
    Full Name:
    Newman
    You have to check your rest pressures on both banks and watch system pressure as it runs. Even out of spec the car will run and even different bank to bank the car will sit there and run. After you have tested the fuel system and if it doesn't have something drastically wrong then look at your ignition system. I had a series 2 here that was presumed to have a fuel system problem due to a hot start concern, ran like crap cold and started to stall out warm and very difficult to get restarted.....It needed an ignition coil.
     
  7. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    thanks for all the comments! May be i have to clarify that the engine is running smoothly and the emissions are well within the legal range for both cylinder banks (HC < 200 ppm, CO < 0.7 %, CO2 >13 %) once it has reached steady operating temperature for water and oil.
    All injectors have been tested, the best six have been retained and the other six replaced by brand new ones.
    The hunting problem (i assume that it is a result of the air/fuel mixture being too rich) does not appear immediately after cold-start but after about 2 minutes (starting at ambient temperature of 20°C or higher) when the auxiliary air valves close and the idle speed is supposed to be reduced to normal. This is the case since i have bought the car 10 years ago and is obviously not directly related to the starting problem with warm engine.
    I would not hesitate to install a new ignition coil to be on the safe side here, but i was not able to get one with the correct specification (primary resistance ~1&#937;, Secondary resistance 6 k&#937;). Most Ferrari specialists tell me to replace the Dinoplex unit which i have tested with the oscilloscope and found the same peak to peak voltage regardless of the cold/ warm condition. And please note: as long as the engine is not switched off, it may run without any malfunction for miles and miles and hours and hours. This does not point to an ignition problem according to my experience.
    I'm quite desperate after all the trouble but i tend to believe that there is something wrong in the fuel system. Either it is accidentally the same failure on both banks or it must be related to the thermal time switch circuit which exists only once for both banks or the control pressure which is linked by a connection tube from the right to the left warm-up regulator.
     
  8. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    As Newman states: Check the fuel pressure. Cold, during warm up, warm, residual pressure, with vacuum and without, with and without interconnecting lines on WUR etc. etc.
    You can easily pass emission tests with an injection system that does not operate correctly. For example with a fully warmed up engine with to low control pressure which means a to rich mixture you can adjust your air flow sensor in a way that emissions will be perfect at idle but at every other position of the air flow sensor you will be off (who knows where that plate is during cranking).
    What coil do you have on the car? Is it the marelli coil with 3 terminals? Did you have any chance to check your VR-sensor in the distributor with the oscilloscope when you can't get it started?
    I thinks these dinoplex AEC104's will all go sooner or later, I'm not a fan of getting rid of original stuff that still works and I really like these old Dinoplex ignitions. But in case of a 400i it's a relatively cheap and simple conversion and for the peace of mind that your ignition box will not leave you stranded some day I would replace it if you would ask me.
     
  9. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    #9 moserpe, Oct 7, 2016
    Last edited by a moderator: Sep 7, 2017
    The coil is actually the original Marelli with three terminals. The Swiss version of the engine does have two sensors in the distributor for emissions control reason (ignition timing "late" on idle). A micro switch in the accelerator lever system changes the ignition from "late" to "early". The starting problem occurs with either sensor switched on.
    I absolutely agree that measuring the various pressures in the injection system would help to answer a number of questions. Unfortunately, at the moment i do nt have the necessary adapters required to connect the pressure gauge.
    The existing symptoms could also point to some false air drawn after the throttle valve since the it's getting worse and worse. Cold start remains possible thanks to the cold start valves. I remember that some 30 years ago starting problems on an Audi 200 5T had been related to non-tight O-rings at the injectors. However they had aged prematurely due to the high charge air temperature. Therefore i will start to check for possible air leaks in the intake system and will renew these O-rings.
    Image Unavailable, Please Login
     
  10. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    Do you know the adaptor sizes you need as i can make you 1
     
  11. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    A detailed investigation of the suction system revealed a number of leaking connections and/or hoses including the conveyors on the airflow metering devices. Sucking false air, the air flow meters did not move from their rest position while the engine was cranked by the starter motor and therefore, the fuel pumps did not work. With cold engine and environnement, the control pressure is reduced and the flow meters were able to move just enough to open the contact for the fuel pump primary relay.

    I was able to get a new conveyor for the r.h. side only (part No. 113413), which is 412 design. Now i'm looking for the l.h. part No. 113414. Anyone knows a source for this part (412 design) either brand new or used but undamaged?
     
  12. Highmiler

    Highmiler Formula Junior

    Dec 8, 2010
    414
    Missouri
    Full Name:
    Greg
    I had exactly the same issue.
    The tale of this saga and the fix is detailed in a thread called The Right Bank.
    Greg
     
  13. moserpe

    moserpe Karting

    Jul 20, 2006
    137
    Switzerland
    Full Name:
    Peter Moser
    #13 moserpe, Aug 31, 2017
    Last edited by a moderator: Sep 7, 2017
    Even after detecting and eliminating all flaws in the ignition system and in the injection system, the hot-start problem reoccurred and developed worse time after time. After stopping the hot engine it was impossible to re-start after a couple of minutes due to lack of injection.
    In the meantime i had found that the valve timing of the left bank was late by some 15 degrees of crankshaft angle. Therefore i decided to replace the timing chain, which was obviously elongated but still within the acceptable wear limits according to the workshop manual. Nevertheless, the manual recommends replacing the chain after 45000 km. My car is now close to 60000 km. For the replacement job, i drove the car to the local car workshop and assisted the job. First action was to loosen the fuel lines on the warm-up regulator. Here i got the final hint about the problem: a complete lack of fuel pressure in the system. No fuel blown out from the accumulators! Conclusion: after stopping the fuel pumps, the accumulators discharged to the fuel tank because of a stuck non-return valve in a fuel pump. Due to the connecting hose between left and right bank warm-up regulators, both the right and left fuel system lost the pressure, the fuel evaporated while the engine was hot and no fuel could be injected upon hot restart. Unfortunately this phenomenon is not listed in the troubleshooting guide of the manual page D26 (copy enclosed).
    After the test-drive with the new chain i did consequently not expect an improvement of the starting problem, which proved to be the case. Now i simply removed the connecting line between the cylinder banks and tried a new start. As expected, one bank fired immediately and the cylinders of the other bank followed one after the other after a couple of seconds. So i had the evidence that my assumption was correct and I decided to replace both fuel pumps on an urgent basis because i wished to participate in a gathering of old Ferrari and Maserati cars the following weekend.
    The pumps were immediately available from the Mercedes dealer, however at a premium price compared to some internet offers with longer delivery delay. The new pumps do now have external non-return valves, which can be replaced individually.
    The following part numbers are applicable:
    Ferrari 121727
    Bosch 0 580 254 975
    Mercedes A 002 091 97 01 replacing A 116 091 02 01

    I would like to add that thanks to all the previous step by step improvements, the engine is now running smooth after cold starting, during warm-up and in hot idling condition like never before. But it took me almost three years to find the real cause since the incriminated valve was working properly now and then giving me the feeling that my preceding repair was successful.
    Image Unavailable, Please Login
     
  14. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    I was on the right track then , a pressure gauge on the k tronic would have been handy. Nice to hear it is going well.
     
  15. Jasonberkeley

    Jasonberkeley Formula 3

    Apr 23, 2017
    1,321
    NW Corner, CT
    Full Name:
    Jason Berkeley
    My car is actually in now for same issue. Cracked o-ring on one of the fuel distributor fuel pressure regulators. Also a leaking fuel pump, and injectors were not holding. New o-ring, two new Bosch fuel pumps, and 12 new Bosch injectors going in now. Should have car back tomorrow. I'll report back if problem is solved.
     
  16. Jasonberkeley

    Jasonberkeley Formula 3

    Apr 23, 2017
    1,321
    NW Corner, CT
    Full Name:
    Jason Berkeley
    #16 Jasonberkeley, Aug 31, 2017
    Last edited by a moderator: Sep 7, 2017
  17. Jasonberkeley

    Jasonberkeley Formula 3

    Apr 23, 2017
    1,321
    NW Corner, CT
    Full Name:
    Jason Berkeley
    #17 Jasonberkeley, Aug 31, 2017
    Last edited by a moderator: Sep 7, 2017

Share This Page