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Mondial 8 weird start issue -- relay related

Discussion in 'Mondial' started by DanielGA, Apr 10, 2018.

  1. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    PS: also a symptom is that sometimes when I accelerate the engine (with or without load), when the RPM comes down on its own, it goes so slow it stalls. Sometimes, it "pauses" around 2k then slowly comes back down to idle. This second behavior is typical. So what does it mean when it does not happen....TDC/tach sensor failure? something else?
     
  2. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    Just measured WUR control pressure when warm...is 70 psi.... guess it is clogged too! And that causes a mixture that is too rich!


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  3. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,275
    No, that makes the mixture too lean. That's the problem right there. Take the WUR apart to clean the screens. Specifically take the diaphragm out, or you'll never get cleaner through the screens.
     
  4. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    Thanks all for your help! Here is an update:

    1. not quite working yet.... :(
    2. I had the fuel distributor and WUR rebuilt; they seem good now
    3. control pressure to WUR is around 45 PSI when warm but it raises after 5-10 minutes because crud builds up on entry to WUR; I can easily clean and then pressure is back where it should be; I know FD is clean, and fuel filter is new, so it must be crud in the line from fuel filter to FD and that despite my cleaning efforts is still there. The FD should have a small filter at entry to it from the fuel line but its disintegrated in mine (= gone) and rebuilders tell me they cannot find that filter.
    4. I was thinking of adding a small new additional fuel filter RIGHT before the FD; any one know the size of the fuel line from the fuel pump?
    5. Also, now that all systems are rebuilt, I think the air-fuel mixture is wrong because the motor did not act right; I have tried to adjust using my ears and nose so to speak but I could not do it well; anyone know of a trick to get that more or less into range? I have to play with the air-fuel mixture screw right next to FD, idle screw by plenum, and auxiliary air bypass by plenum.

    D.
     
  5. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,275
    The fuel line from the filter to the FD is rather short. You could disconnect both ends, and spray cleaner from the FD end to clean it out. Or perhaps just replace it. The last time I replaced my fuel filter, it was full of junk. I have resolved to replace it every year now. With extra long wrenches, it's not that hard to do.

    For mixture adjustment, remove the air filter box. Warm up the engine. Rev up to 3,000 RPM, and press down very slightly on the air vane. If the RPM increases, that means you're too lean. Start from a lean setting, then adjust rich 1/4 turn at a time. Make sure the engine is hot, because there is a big difference between hot and cold fuel mixture. This is tuning for power, not emissions.
     
  6. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    I did clean the FD, maybe should do again. If I want to change it, do you know the compression end sizes?

    Thanks for the mixture adjustment routine! I suppose you mean have some keep RPMs at 3k, and then adjust as you say?

    I also found this at cisflowtech.com:

    After assembly of the fuel system, run the fuel pump and depress the air flow sensor plate for a couple of seconds to bleed air out of the fuel distributor. Remove one injector line from the top of the fuel distributor, and while looking into the injector port in the top of the fuel distributor turn the mixture adjustment screw clockwise until the port just starts to fill with fuel then turn the mixture screw 1/2 turn counter clockwise. Reinstall the injector line, start the engine and adjust mixture when it reaches operating temperature.


    thoughts?
     
  7. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,275
    I think the cisflowtech starting adjustment is for recently assembled parts, just to have a starting point. I thought you already had the engine running.

    The problem with trying to adjust the CIS while it's running is that you create a vacuum leak when you have that adjustment port opened. By depressing the air vane slightly, you are richening the mixture. That should tell you where you're at with the adjustment. Optimum mixture will give you the highest RPM for a given throttle setting.

    Not sure what size the fittings are, but I'm sure a shop could assemble new hoses for less than what the dealer cost of the parts are.
     
  8. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    All, thanks for help! Turns out my fuel tank was too
    dirty despite my prior simple cleaning...is clogged up filters and reduced system pressure; now after a comprehensive cleaning with an auxiliary pump, lots of water, lacquer thinner, and time, it seems good; for the first time ever system and control fuel pressures seem to stay ok!!! Mixture setting is out of whack; I think I adjusted it correctly, but could be wrong; when driving power is very low and doesn’t feel right; when I go downhill and Gravity accelerates the car, it turns off (or maybe just not enough Gas in tank?)...any more pointers to adjust mixture? Somebody with experience in Midwest US?


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  9. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    All, update:

    VERY LOW POWER ENGINE, HELP!

    I did this: "After assembly of the fuel system, run the fuel pump and depress the air flow sensor plate for a couple of seconds to bleed air out of the fuel distributor. Remove one injector line from the top of the fuel distributor, and while looking into the injector port in the top of the fuel distributor turn the mixture adjustment screw clockwise until the port just starts to fill with fuel then turn the mixture screw 1/2 turn counter clockwise. Reinstall the injector line, start the engine and adjust mixture when it reaches operating temperature." from CIS/Flowtech guidelines.

    Then start car and warm it up.

    Then when running if I adjust mixture screw about 1/4 to 1/2 turn more (CW, rich) it seems unhappy and wants to stall (at idle). Similarly, if I turn about 1/4 to 1/2 turn less (CCW, lean) it wants to stall (at idle), so I think I am more or less in the middle mixture setting. But I am not 100% confident on this.

    I also did this with the bypass valve (big knob) shut.

    Then I adjust idle to 600-700 then use bypass valve to get around 1000-1100.

    I think this is all correct, modulo small errors.

    In the meantime, my fuel pressure is FINALLY correct the whole time: system pressure near 80 PSI and control pressure 45-48 PSI.

    Engine starts easy when cold or hot, I think.

    HOWEVER: there is no power. I have gone for spins around the block and it simply has no power, and few times stalled (but restarts after 1-2 cranking attempts). I can even tell just going up and down my driveway with a mild incline. What is it?????

    Some observations:

    1. the tachometer goes crazy every once in a while (quickly oscillates +/- several thousand RPM, but of course engine is steady). I visually inspected the 3 speed sensors on the engine, and I think I tested the ohms of the RPM sensor and it seems ok (not sure anymore, so many things...).
    2. the idle is sometimes lower then it should be (like down to 300 RPM)
    3. I checked that both banks are working by disconnecting one entire bank on purpose (from the coil); when only a single bank running it is even weaker and cannot accelerate engine (did not try driving).
    4. Sometimes the brake pedal (when at low RPM) goes hard, like if no vacuum assist? Is this related? just slow engine?

    Can it be a timing issue because the RPM/TDC sensors are bad? Would that cause this issue?


    Suggestions?
     
  10. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,275
    For mixture setting, bring the RPM up to 3,000 then press ever so slightly on the air vane. If the RPM increases, you are too lean. Too rich symptoms are dying at idle, and difficult hot starting.

    The car should actually run reasonably well on 1 bank. You basically have a 4 cylinder engine at that point.

    Misfiring / low power can be caused by multiple faults. Start with a compression check. I would like to see those numbers.

    Valve seats wear faster than shims/cams, so you have to check/adjust those, or you will eventually have the valves not closing all the way.

    Even though your jetronic pressures are correct, you could still have a clogged injector. Best thing is to pull them all out and check the spray pattern, that they all come on at the same time, etc.

    High voltage arcing can occur at the spark plugs, extenders, wires, rotors , caps, coils. If there is high voltage arcing, there will usually be a visible path on the various components. Also, you can set your AM radio to the lower channels, and hear the arcing coming through the radio/speakers. The Cavis spark plug wires are known to go bad, increasing resistance. Spark plugs can be cleaned to like new condition with a propane torch. Check the gaps. Check the length of the ignition sensor wires, that they are not rubbing against a ground, shorting out at some point.
     
  11. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    17,537
    Texas
    Full Name:
    Steve Magnusson
    Typically not as a bad flywheel sensor would cause a whole bank, or both banks, to lose spark (and your description seems more like weak, but smooth, running and not erratic misfiring). Any chance that the intake vacuum supplied to the DigiPlex igniton ECUs has become disconnected? A fairly easy next step might be to put a timing light on it, and see if the ignition advance on both banks is quasi-reasonable vs what's shown in the Mondial8/QV WSM (and/or confirm it changes when.vacuum is applied and removed from the DigiPlex ECUs). Just a thought...
     
  12. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    Success!!!!! At last!!!!!!!

    Following spicedriver, I inspected my new injectors...I took them all out and cleaned them with carburator spray and compressed air...remember my fuel tank was terrible, so they had some bits of varnish in them, even though they were new...now fuel tanks thoroughly cleaned and everything after is new/cleaned/replaced...

    At last power and glimpse of potential fun driving!

    I drove a bit around town but did not press the accelerator too hard yet...it would stall when I only had a few gallons in the tank, now have 8-10 gallons and stalling issue is gone...

    For the first time, I spent most of car-time today doing something more fun like washing, polishing, waxing, and cleaning the interior, make trim black again, etc... looks like new now!

    *** Of course something new has to appear, now the oil pressure light just barely comes on when at idle (low pressure), but when I accelerate it goes back up into the normal range 70-80ish PSI as per the instruction manual; at first I checked oil and put some more in...its hard to read the amount of oil with the odd dipstick it has...I think oil is plenty (and new; recently changed). Tomorrow I will observe some more...not sure what to do...manual indicates oil pressure can be regulated with a valve...no clue if its easy to or not.

    Tachometer is still a bit crazy every once in a while, but oh well...

    For now, I want to drive...

    Not done, but significantly farther at least!!! Thanks spicedriver and Guido and others!!!!
     
  13. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    All: here are some pics! Btw, oil when cold is 80psi; when driving cold or warm stays around there; when quite warm at idle goes down to 45 or so as per indicator and light just barely flickers on; slight rpm increase and all good; not sure of issue; will have my mechanic check with an external gauge in place of oil pressure sending unit.... Image Unavailable, Please Login Image Unavailable, Please Login


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  14. theunissenguido

    theunissenguido Formula 3
    Silver Subscribed

    Jan 21, 2004
    1,117
    Argent/Brasil/Blgium
    Full Name:
    Guido
    Finaly you have the some fun to drive the car...great to hear !!

    Guido
     
  15. DanielGA

    DanielGA Karting

    Mar 19, 2018
    89
    Midwest
    Full Name:
    Daniel A.
    Oil checked out good; basically pressure is a bit too low when at low idle (500), hot weather, hot engine.... goes to like 35, but that's ok. At 1000 RPM hovers 40-45 but after a hard drive, touches 35 (when light comes on). Mechanic tells me behavior is fine. Maybe can put 10-60 oil for hot weather and hot driving... :)

    Breaks are great!

    Sound is great!

    Next are minor things: tachometer, need new muffler (maybe will do cat delete) -- both are 36 years old. Thinking simple custom exhaust with something like Flowmaster or Magnaflow dual muffler...dont need or want to spend much...

    I am eyeing electronic ignition (Electromotive), full EFI conversion, or just keeping it stock....

    I take my other car to the track everyonce in a while...I want to take this one too every once in a while. Fun stuff!

    Thanks all!
     

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