HELP: Mondial 3.2 backfire/stumble/running lean after 3K rpm | Page 2 | FerrariChat

HELP: Mondial 3.2 backfire/stumble/running lean after 3K rpm

Discussion in 'Mondial' started by LA_Rari_22, Feb 13, 2021.

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  1. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    42
    Full Name:
    Len U
    I wish it was that, prob wudda been fixed a long time ago. I actually first replaced both ignition modules first (the generics). no luck so I replace both coils ($$ btw) which comes with the original module. it wasn't ignition related. thought it was that actually. its the fuel distributor for me, been doing the Techron slow flush which has been working so far.
     
    soucorp likes this.
  2. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,814
    Old Dominion
    Full Name:
    Mike
    Good to know, since I've had my car, the ignition module and clutch slave cylinder leak was the only 2 issues and I was able to fix it myself along with DIY cam belt replacement. She starts up 1st time everytime. Hope you get it sorted out.
     
  3. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    I have also had a problem with an ignition module. The symptom displayed was an intermittent loss of 1 bank of cylinders. The car basically became a 4 cylinder. There were no backfires, but it was really down on power.

    I replaced an entire coil unit. I probably could have gotten away with just the little black ignition module for $20. Ducati motorcycles, and many other vehicles use this same part.
     
  4. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    The trick with checking them is to start the car from cold, ie next morning . Then drive it until the backfiring starts, stop the car with engine running- see if one coil has a temp difference by hand. The warmer one is breaking down and might be source of your problem if coil related
     
  5. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    What I did for testing was to swap the coil positions. When I started losing the other bank, I knew it was a faulty coil assembly.
     
  6. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    I was lucky with mine as it was very obvious by the temp diff. I was 3 hours from the dealer plus a 4 hour ferry ride and they put me onto this test to see if it helped.
     
  7. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    42
    Full Name:
    Len U
    UPDATE

    Jkstenvens2... After a month of running the car (about 1000 miles) almost daily and using Techron, the problem never went way. The only way I could get the car running decent is by adjusting the lean/rich screw near fuel distributor and setting it to rich. As a consequence, I began experiencing hard warm starting and after a while some bogging when cold. I replaced the WUR with a rebuilt unit and it made it obvious that problems were within the fuel distributor.

    I have sent mine out to Larry at CIS flow tech per your recommendations (4-6 weeks wait)... I hope this will solve the issues.

    spicedriver... I tried the Techron and it slightly helped in the beginning but eventually got worse towards the end.

    to be continued...
     
  8. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,628
    Canada
    Went through the same process on my 1988 3.2, thinking it must be spark. The rebuilt fuel distributor will solve for things. You should change spark plugs and the O2 sensor while you wait, they will no doubt be badly fouled from the prior poor running.

    Any car with the original fuel distributor internals after 32 years should do the rebuild. There are rubber parts in there, and it is amazing they last as long as they seem to.
     
  9. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    The only problem I've had that got worse over time, and needed to have the mixture richened, was the accumulator. But you've said that was replaced already. Another possibility is a vacuum leak.

    Hopefully, the rebuilt fuel distributor will fix the problem, or at least eliminate that as the cause.
     
  10. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    42
    Full Name:
    Len U
    UPDATE

    Just got my rebuilt fuel distributor back from CIS flow tech and YESSS.... it fixed the problem. Still some tuning to be done (going back to lean) as I had to richen the mixture to compensate for the problem

    btw moysiuan, I took your advice and replaced the spark plugs as they were fouled as I set the mixture rich prior to rebuild

    Thank you all for helping and giving your insight/advice =)

     
    moysiuan likes this.
  11. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    I pointed you to this in the beginning, with it being the distributor have you changed the engine oil since you repaired the distributor. It will have been dumping unburnt fuel past the pistons into the sump.
     
    moysiuan likes this.
  12. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    Glad you made progress with this.

    Did Larry happen to say what exactly was wrong with your fuel distributor, and what he did to fix it ?
     
  13. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    42
    Full Name:
    Len U
    Not specifically but I can see and feel how freely the plunger moves down now. I missed the call for update but message said diaphragm was dimpled and needed cleaning inside. Still tuning it, going back to lean is making the car run better as of recent

     
  14. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    When they go wrong it makes the usual fuel balance to each injector to be way out. Some get too little and some too much, it can be enough to wet the plugs etc and then the backfiring. The example i saw was that bad the sump level was coming up as the unburnt fuel poured past the rings and you could smell the petrol on the dipstick.
     
  15. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    42
    Full Name:
    Len U
    I did change the oil prior to installing the rebuilt fuel distributor... and the oil did smell like gas. I also changed all spark plugs and 2 were more fouled than the others.

     
  16. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    It will go for years now u have that done
     
  17. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    "Go wrong" isn't really very specific. I suspect the filter screens, or metering slits inside the FD were clogged with fuel varnish, and all they really had to do was clean them with some solvent.

    But it would be nice to hear from Flowtech as to what problem they found, and what they did to fix it.
     
  18. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    They have rubber diaphragms in them from what i recall
     
  19. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    Sorry, I missed this post. "needed cleaning inside" sounds about right. Best not to let these cars sit for more than a week, IMO.
     
  20. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,829
    Isle of man- uk
    If you look up Bosch k tronic repair kit it shows the renewable parts inc the rubber diaphagm
     
  21. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    Right. And I would wager that if the diaphragm was replaced without doing the "needed cleaning inside", the faulty running symptoms would still be there.

    This would be akin to replacing gaskets in a carb, when the actual fault was a jet clogged with varnish.
     
  22. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,628
    Canada
    The rebuild includes splitting the case, and cleaning out the very small holes in the casting and the various delicate filtration screens inside. Once you split the case, replacing the diaphram and o rings with new ones makes sense, the cost is minor for the rubber internals. But most importantly the rebuilder recalibrates the flow for each port, which can be altered through the split and clean process, such that each port flows to spec. They use the Bosch factory calibration equipment. The plunger also has to be precisely set, which they do using the flow equipment.

    If your unit is likely clean (ie. the car has never sat for too long and gotten gummed up), but any of the rubber parts have perished or failed, one can buy the ebay kits and do it yourself. It is a meticulous job, but quite doable. But one can not do the calibrations without the flow equipment, although there are some enterprising you tubers mostly working on similar Mercedes who have some techniques for getting close. As long as you don't break anything, giving it a go in some instances would make sense for the curious handyman.
     
  23. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    Of course if you're going to disassemble the FD, it makes sense to replace the various gaskets and diaphragm. Flow rates can be easily checked with a set of graduated cylinders.

    The point is, this is not what is causing the problems.

    The problems are caused by fuel varnish buildup from old gas that is given time to evaporate, and leave behind a residue. This is very stubborn material to clean off. A common problem with motorcycles that are not run for the winter. You go to start it in the spring, and it either won't start, or runs very badly. Many carbs have a drain for the float bowl, so you can drain the gas out before it goes into storage. This prevents the jets from getting clogged with varnish. I believe the K-Jet system is even more sensitive to varnish than carbs were. And it's not just the FD, there are filter screens in the injectors, and the WUR, and the fuel pump can rust weld without lubrication from gasoline.
     
  24. jkstevens2

    jkstevens2 Formula Junior

    Aug 25, 2015
    278
    Winter Park, FL
    Full Name:
    JK Stevens
    Such a spirited debate regarding fuel additives and their amazing ability to clean out the fuel distributor.........the fact is the plastic and rubber components of the 86 Mondial are literally biodegrading. Have you looked at your original windshield wiper reservoir lately? The thing is completely decomposing as the petroleum based plastic are becoming unstable. The molecules are separating........The same thing is happening inside the fuel distributor. The rubber diaphrams are splitting and decomposing. I suggested LA Rari send off the FD to have a real expert service the part........I am sorry Spicedriver, I just dont agree that sticking alcohol solvent in the FD will disolve the buildup to the point that it will pass thru the super small regulating orifaces and filter screens. At least we were on the right path.......Every post I ever read on Fchat always goes the route of the electrical, the car needs ignition modules, distributors, voltage regulator..........the Fuel Distributor is by far the most mis-understood, mis-diagnosed problem with the Mondial 328 engine. Unless Mondial owners are putting non-ethenol gas in their ferraris, they are pumping ethenol into the car. Thats corn alcohol......its super corrosive and it leaves huge white deposits on the inner wall lining of gas lines tubes carbs fuel injectors alike. I cant tell you how many pressure sensor monitors I have replaced in my Chevy suburban gas tank because ethenol has literally eaten the rubber ribs fastener /washer that holds it in the top of the fuel tank. Thats a car 20 years younger than my 1986 Mondial and the rubber is getting eaten by the fuel. 20 years of rubber advancements? and we are arguing that the rubber diaphrams inside the FD are fine? They dont even recommend you put ethenol gas is outboard boat motors, lawnmowers and weedeaters. Because it so corrosive. I replaced the fuel lines on my Mercury outboard motor and they looked like diseased human arteries full of plaque cholesterol......a white film on the inside, almost like a lining. Now we all agree, that the Ferrari motor is the heart and soul of our beloved machines........why would we even consider putting ethenol gas in them? Everybody......thank you for the input on this subject. Its what makes Fchat so great.
     
  25. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    My 86 still has the stock FD that's never been opened. Works like new. Actually better than new, because I've replaced the WUR with a vacuum enrichment type from a 911. Our state went E10 in 2006. I believe the big problem with ethanol in boats is the fiberglass fuel tanks.

    The washer reservoir is an interesting issue. I'm thinking the manufacturer changed the formula for their plastics at some point, because the earlier versions are still holding up. I've seen other equipment that also has some faulty plastic formula that becomes brittle over time. You go to pick it up and it disintegrates in your hands.
     

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