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

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

  1. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    So I've been chasing this problem for some time and threw quite a few parts at my 1988 3.2 Mondial. Every part has helped make it run better but I still have this annoying problem...

    PROBLEM: Starts up no problem, idle is not holding steady, tiny rpm bounce, idle holding at 900-1000 rpm. When cold engine is hesitant and stumbling with lean backfires on acceleration throughout rev range. After 5-10 minutes of running engine, 3000-6000rpm there is stumble/hesitation/backfire but after 6000rpm power kicks in (like a sudden boost of power). After 20 minutes of running, it gets better! Same stumble from 3-5.5k rpm but power kicks in about 5.5k rpm. After 30-45 minutes same stumble/backfires from 3-4.5k rpm then power kicks in at 4500rpm...

    They are lean misfires as dash stop light has lit up a few times(lead me to replace cat and o2 sensor)

    Parts I've replaced chasing this has made the car run better, performance use to be really bad and hesitating like crazy. Still getting lean misfires and poor performance from 3-5.5k rpm, 3-4.5k when running a while.

    Here's the list of parts I've replaced so far (ignition and fuel)...
    Ignition: new coils with modules, all spark plug wires, all spark plug extenders, new plugs, new dist caps and rotors, crank sensor
    Fuel: new fuel pump, new fuel accumulator, new fuel filter, Bosch brass fuel injectors and seals
    Exhaust: new o2 sensor, test pipe (got rid of cat for now), exhaust is new.

    -My 1988 3.2 Mondial doesn't have the frequency valve with fuse in trunk btw
    -Its K-Jetronic with lambda.... buzzing heard from valve near fuel distributor

    HELP!!!!!!! What is causing this problem? ... running out of ideas... anyone experience this b4

    Thank you all in advance for your input =)
     
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  3. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    This system is easy to clog from fuel drying out. Try to get the entire system filled with Techron, and let it sit for a few days. This will clean everything to brand new. The FV buzzing is trying to enrich the mixture.
     
  4. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    Hi Spicedriver... has this happened to you? Im on my second bottle of Techron fuel system cleaner and its still the same.
     
  5. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,194
    Uk
    Have a smell of the dipstick for fuel. Is the sump level coming up ?
    If so then look on e bay for a repair kit for the fuel distributor, on the distributor where the pipes are attached to the top with banjo fittings you will see a Bosch id label on the side. Use this to get the correct kit.
    The Mondial a friend of mine had backfiring problems traced to split diaphragm in this. The equal metering of the fuel is upset and you get uneven fueling so some get too much and passes the pistons into the sump oil.
    Its worth a try as kit about £55 . Same system used in volvo and others.
     
  6. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    Yes it has happened. The worst thing IMO, is to let the car sit unused. This is when I get problems develop. Try to run the car weekly at least. And add a bottle of Techron with every tank of fuel. It really is amazing stuff.
     
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  8. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    spicedriver: It funny u mentioned that because the car was running great until I let it sit for 1 month. Since then, ive been having a hard time shaking off this problem. How many Techron's did u use till it cleared up for u??

    Mike 32: no smell of fuel on the dipstick. I actually just changed the motor oil 10 40w before the problem started. Its actually running lean causing the misfires.

    Could it be the Warm up regulator?? they are $$$, might try and clean it first possibly rebuild mine...
     
  9. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    Yes, a clogged WUR can give you a lean mixture. There is a filter screen in one of the ports which clogs. You will have to remove the diaphragm in order to clean it out, because of the pressure on the other side.

    There are also filter screens inside the FD, and fuel injectors as well. Rather than taking everything apart, I would just try to fill the system with Techron. Drain the fuel tank, and add enough Techron to completely fill the system. You should be able to hear the injectors working, when you press down on the air vane. Let the Techron work for a couple of days before starting the car. It will clean everything out.

    Also, whenever you change a major component in the fuel system, you may need to adjust the mixture screw, and/or system/control pressures.
     
  10. jkstevens2

    jkstevens2 Karting
    Silver Subscribed

    Aug 25, 2015
    223
    Winter Park, FL
    Full Name:
    JK Stevens
    I had the very same problem with my 86 Mondial. My mechanic kept insisting I use fuel injector cleaner......that was part of the problem. IMO it loosened up the ethanol deposits that then clogged the fuel distributor.......or very well ate through the rubber diaphrams inside the fuel distributor. Send the fuel distributor to a Larry Fletcher in Mobile Alabama 251-929-3771. He will rebuild it for about $500 and your Ferrari will run smooth again. Trust me, I have gone down the road you are traveling........replacing everything from distributors to fuel pumps to the voltage regulator in the trunk. Oh yeah, you do have a voltage regulator. It in a panel that rests upside down under the right side of the trunk. You cant barely find it. I have done all of these things with no positive result. Its the fuel distributor plain and simple. And by the way, run non-ethenol gas from now on. Good luck
     
  11. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    That sounds like a good way to clear out the fuel system. Do u think 2 bottles of Techron on a near empty tank would work too??
    What do u think of just removing the WUR and flushing it with Techron to speed things up???

    Today, I just added Techron and cleaned the connectors from the WUR with deoxit and it ran surprisingly a little better. still not great from 3-4.5k rpm but a very slight improvement!
     
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  13. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
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    Len U
    jkstevens2: What happened was there was a slight stumble after I let the car sit for 1 month. I thought ok fuel cleaner and some run time, got worse the next day, then I threw a bunch of parts at it (barked up the wrong tree with ignition) and its back to the original stumble/hesitation at 3k rpm.

    After redoing the whole ignition system, I know its fuel now. Was afraid either fuel distributor or WUR as they are $$$

    The Techron did help today, maybe I wont overdo it
     
  14. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    If you want to clean the WUR quickly, you will have to remove the membrane from the fuel cell. Then you can use a carb cleaner spray. This is not difficult, but you have to make sure that everything goes back together, the same way it came apart. I would also bet that the filter screens in the injectors are also clogged. These will need to be soaked.

    Gas doesn't last nearly as long as most people think. It's best to dump out the old gas.

    Sending out parts to a rebuilder, just because you've got a varnish build up is the expensive way to fix it.
     
  15. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    t
    Thank you for the input. Wondering if I need the rebuild kit fo the gasket once I split open the WUR? or will it go back together and just use rv silicone to reseal
     
  16. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    Silicone will not seal gasoline. The rubber gasket in the fuel cell does not have any sealer on it. The new gasket from the rebuild kit will be thicker, and it will change your pressures/fuel mixture. If you have all the right gauges, and know how to adjust the pressures, that's not a problem. Otherwise, you might want to leave the original gasket in place. A new gasket will make your mixture richer (lower control pressure).

    There is also a rubber gasket that goes around the perimeter of the case. This is just to make an air tight seal.
     
  17. Wingnut

    Wingnut Karting

    Feb 11, 2005
    91
    Corolla, NC
    Hylomar Blue gasket sealer works great for sealing fuel gaskets.
     
  18. jkstevens2

    jkstevens2 Karting
    Silver Subscribed

    Aug 25, 2015
    223
    Winter Park, FL
    Full Name:
    JK Stevens
    Send the warm up regulator to Larry Fletcher too. Its the same mechanism just simplified for one outlet. Everyone I run into underestimates the importance of the Fuel distributor and the total impact it has on the entire workings of the engine. Its a very delicate piece of machinery. It operates on specific rates of liquid pressure, liquid dosage and if you have the means to measure and quantify these, then by all means rebuild it yourself. But there are adjustment screws on the fuel distributor and if those need to be adjusted......game over. You can disconnect both the warm up regulator and the fuel distributor yourself, mail them off to be re-built and reinstall saving yourself the shop fees and markup. Its not about varnish buildup. The ethanol (corn alcohol) in our gas is super corrosive. The plastics and rubber components of 1986 (and any for that matter) are physically biodegrading. The molecules are breaking down and the plastic is falling apart. Look at your windshield wiper reservoir. Its probably crumbling like mine. They become discolored and start to decay. Now take those parts (and in your case its the rubber diaphragm inside the fuel distributor) and immerse them in gasoline that contains ethanol. Oh yeah pour some techron on top........all that is is pure alcohol and you are going to have problems. Good luck!
     
  19. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    thank you for the response! so the problem symptoms I described is from a failing fuel distributor and not the WUR?

    BTW... The Techron as recommended by spicedriver has been helping tho. I just put one per full tank and been the car driving daily so far. It still runs crappy from 3-4.5k rpm but a lot better that before.
     
  20. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    Hey, the Techron with every tank has been helping along with using the car daily. I haven't tried the Techron flush but the small amounts per tank has been working so far. I mean the car still runs like crap but "better" crap at 3-4.5k rpm. U were right, the problem happened as I let the car sit for 1 month.

    Wondering, how many of those Techron's did u use to clear the problem for u?? I didn't take apart the WUR, gunna use the car more to see if problem clears on its own...
     
  21. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    #18 spicedriver, Feb 18, 2021
    Last edited: Feb 18, 2021
    Techron has been around for a long time, so I wouldn't worry about it damaging engine parts. Use a bottle with every tank of gas. And keep a note of when you're buying gas if the car isn't used every day.

    As long as you keep running the car every day, and use the Techron with fresh gas. This problem will likely clear up in a few weeks.
     
  22. jkstevens2

    jkstevens2 Karting
    Silver Subscribed

    Aug 25, 2015
    223
    Winter Park, FL
    Full Name:
    JK Stevens
    Yes, I think its a fuel distributor.
     
  23. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,194
    Uk
    This fuel injector cleaner is ok once a year, if you now think the distributor needs fixing you can do yourself on the kitchen table. Just take the number off the head and look on e bay for the bosch repair kit
     
  24. Subito Grigio

    Subito Grigio Karting

    Jun 2, 2009
    211
    My ‘83 Cab is with SRI Dave Helms now because Fuel distributor is broken. The car has about 70,000 miles. SG


    Sent from my iPhone using FerrariChat
     
  25. LA_Rari_22

    LA_Rari_22 Rookie

    Nov 3, 2019
    27
    Full Name:
    Len U
    UPDATE: I've been using the car daily and running one bottle of Techron per half tank gas....and its been running BETTER!!! backfires from 3-4K rpm but not hesitating much and running smoother the more I drive.

    spicedriver... so do you put Techron with every tank from now on? my Mondial can sometimes be a garage queen (due to me not having time to drive out). I'm glad you pointed me to the least expensive yet fun solution to my problem btw. big thanks =)
     
  26. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,194
    Uk
    You are just papering over a problem, if it has not cleared by now you have an existing problem
    Can you rig up a multi meter on some long wiring and observe the voltage supply to the coils when driving. Any variation in volts will give you a backfire.
     
  27. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,536
    I use it religiously.

    Varnish is a big problem with motorcycles that sit too long. So I had some stinky old gas, and decided to experiment with it. I put it in a glass jar, and let it evaporate. This left a thick layer of varnish stuck to the bottom of the glass. It was like taffy. So I tried to remove it with powerful solvents like Acetone, B12, and some of the other cleaners. Nothing really had any effect. So I poured in a bottle of Techron. Nothing happened at first, so I let it sit overnight. The next day, the Techron had stripped away the varnish from the bottom of the glass. It was completely cleaned off. I was astonished !
     
  28. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,808
    Old Dominion
    Full Name:
    Mike
    #25 soucorp, Feb 26, 2021
    Last edited: Feb 26, 2021
    Hi, I haven't been on FChat in a long time but read your question. My car did the same as yours and I also have an 88 3.2.
    The backfire and lost of power was due to a bad ignition module ~$190 part. Your car has 2 ignition coil modules for each bank. Try replacing one or both sides, the problem should go away, at least it fixed my issue after troubleshooting for a month. Good luck!

    Here is my thread on this issue:
    https://www.ferrarichat.com/forum/threads/rough-idle-loss-power-backfire.364375/
     

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