News

Rough Idle, Loss power, Backfire

Discussion in 'Mondial' started by soucorp, Apr 18, 2012.

  1. Jeka

    Jeka Formula 3
    Silver Subscribed

    Nov 20, 2010
    1,083
    Rotterdam
    Full Name:
    Johan
    Superb job and a superb description of the work performed!
     
  2. jgoodman

    jgoodman F1 Rookie
    Rossa Subscribed

    Aug 29, 2009
    2,873
    Central PA
    Full Name:
    Jay Goodman
    Great job Mike. I like your perserverence. I prophylactically just replaced both of my ignition modules, as I thought I was beginning to have the same intermittent "lack of spark" issue, even though I just replaced one of the coils with the newer version from Magneti Marelli approximately 2 years ago. Car started right up, but because of the weather up here, could not test it under load. Now I purchased the inexpensive replacement modules first to see if that was the problem. I bet it was. Engine is already purring better, I think. I now have an extra coil and three extra ignition modules, all of which are original Magneti Marelli components from 1987. I'd like to test all four components to see what works and what doesn't.
     
  3. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,805
    Old Dominion
    Full Name:
    Mike
    #128 soucorp, Jun 7, 2012
    Last edited: Jun 7, 2012
    Hi Jay, best thing to do is hook up a timing light to each of the plug wires and see if you are missing any sparks when the RPM dips at idling, then determine which bank is misfiring. But if you replace both power modules, that should do it unless its the coils. The backfire and rough idling is another sure sign. Also don't forget the heat sink cement that goes in between the power module and coils!

    All the best,

    Mike
     
  4. Lino

    Lino Formula Junior

    Jul 7, 2010
    923
    Montreal Canada
    Full Name:
    Lino
    Hi Mike,

    I am having some rough idling and when I give it gas it drops well below 800 rpm and wants to stall. It usually revs at 1000rpm steady and when operating normally you can give it gas and will come to idle steady at 1000 rpm. I also get backfire and power loss. You can tell when driving when you let off the gas pedal somthing is wrong. After about 30 min of driving it goes away.

    Does this sound like your symptoms? I am going and get a spare module from my mechanic to trouble shoot. I also have spare coils.

    Why do you need to use that whit paste? Do I need that to trouble shoot?

    Lino
     
  5. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,805
    Old Dominion
    Full Name:
    Mike
    #130 soucorp, Jun 8, 2012
    Last edited: Jun 8, 2012
    Hi Lino, it sounds like it could be the power modules. rpm at normal idle=1000 +-100.
    Not sure about the 30 min it goes away. But you have a T. Not sure if your car would have the same components. plug a timing light and see if you get misfiring and trace it to the coils. It could be distributor, rotor, or spark plugs/wires.
    Thermal grease (also called thermal gel, thermal compound, thermal paste, heat paste, heat sink paste or heat sink compound) is a viscous fluid substance, originally with properties akin to grease, which increases the thermal conductivity of a thermal interface by filling microscopic air-gaps present due to the imperfectly flat and smooth surfaces of the components; the compound has far greater thermal conductivity than air (but far less than metal). In electronics, it is often used to aid a component's thermal dissipation via a heat sink.

    I dont think your car has a frequency valve protection relay so thats out.
     
  6. davebdave

    davebdave Formula 3
    Silver Subscribed Owner

    Mar 18, 2007
    2,372
    Northern VA
    Full Name:
    Dave W
    We had two separate issues that gave us similar symptoms. One was an o2 sensor and the other turned out to be a bad crank sensor (although the crank sensor problem got worse as the engine got hot)(In both these cases, however, we had intermittent Check engine lights and the ECU codes indicated the problem) Also, since your engine recently came out, check you ecu grounds...they are grounded to your red cam covers and maybe one got a little loose.

    Dave
     
  7. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,805
    Old Dominion
    Full Name:
    Mike
    Good call Dave. What gets me is Lino says it goes away after 30 mins of driving?
    What would cause that to happen in the ignition system? I would ask is it repeatable every time or is it random, meaning sometimes 15min, 30min, an hour? I code and test software looking for patterns, troubleshooting is what I do best. I would start from one end of the ignition system (basic flow) to the other end, testing and replacing the cheaper parts first.
     
  8. Lino

    Lino Formula Junior

    Jul 7, 2010
    923
    Montreal Canada
    Full Name:
    Lino
    Mike and Dave,

    Thank you. I drove the car all day and it ran great.

    I will check the grounds and I have changed one crank sensor already, I guess it won't hurt to change the other. The thing is now its running better then ever. I passed by my mechanic this morning for a quick espresso and it was running on all 8 revving at 1000rpm, he suggested that it may be the module for the cats located next to each ECU, he had a 348 with the same issue. Those modules are there to protect the cats from overheating and supposed to shut down the affected bank i am told but i dont think its that. Anyway at this point I will be taking all your suggestions and trouble shoot when the problem occurs. I have a spare crank sensor, ignition module and coil so I will start the trouble shooting with these parts.

    Dave I am not familiar with code reading, can you read the codes on the T. I thought you can only do that on the 348. Is there any thread on this?


    Thanks
    Lino
     
  9. davebdave

    davebdave Formula 3
    Silver Subscribed Owner

    Mar 18, 2007
    2,372
    Northern VA
    Full Name:
    Dave W
    #134 davebdave, Jun 9, 2012
    Last edited by a moderator: Sep 7, 2017
    Hey Lino, it depends on which Motronic version you have. Our 1992 has the Motronic 2.7 which allows code reading by pushing buttons in the trunk near the ECUs. Instructions are here..

    http://www.my348.com/

    If you are not sure which version you have, pop the engine lid and see how many throttle position sensors you have. If only one on the left bank you have a Motronic 2.5 and need an external computer to read the codes. If you have a 2.7 you will find the below button(s) in your trunk behind the firewall panel...follow the 348 instructions to get the codes.

    Dave
    Image Unavailable, Please Login
     
  10. Lino

    Lino Formula Junior

    Jul 7, 2010
    923
    Montreal Canada
    Full Name:
    Lino
    Hi Dave,

    No button for 89T, I guess it's that fancy switch box to read codes.

    I took the car out again for quite a long drive and it ran ok so maybe a gremlin. I hope it remains that way.

    Thanks,

    Lino
     
  11. davebdave

    davebdave Formula 3
    Silver Subscribed Owner

    Mar 18, 2007
    2,372
    Northern VA
    Full Name:
    Dave W
    Excellent! We've had a few gremlin's fix themselves over the years. I think the connectors are to blame. Stabilant 22 helps but one day we'll spring for Dave's gold kit and hopefully be done with it.

    Dave
     
  12. soucorp

    soucorp F1 Rookie

    Sep 20, 2011
    4,805
    Old Dominion
    Full Name:
    Mike
    The gremlins just adds character to the car, doesn't it? I noticed my "Slow Down" lights flicker sometimes driving in pouring rain. Any other conditions it never comes on. At the moment, my car runs beautifully, every note is in tuned. However, Aug-Sept I'll be doing the belts, Luca said he can help me but I have to get an air compressor/tools first which I was looking to get a set anyways for my garage. That should be interesting and the last thing I have to do to my car for a long time.
     
  13. davebdave

    davebdave Formula 3
    Silver Subscribed Owner

    Mar 18, 2007
    2,372
    Northern VA
    Full Name:
    Dave W
    Well there's your problem! What are you doing driving in the rain? :)
     
  14. greg328

    greg328 F1 Rookie
    Silver Subscribed

    Nov 17, 2003
    4,090
    Austin, TX USA
    Full Name:
    Greg
    Excellent thread, thanks for your perseverance Mike. Learned a lot.

    I'm currently experience a no-start problem with my 87 328. I wonder if the problem could be an ignition coil module? I checked for spark with an inline spark tester, no spark so we know it's ignition, not fuel that's my issue.

    I don't have a rough-idle, single-bank issue, I have a total non-starting problem. Cranks hard, but just won't catch. Problem has been intermittent until this morning, the car left me stranded. It ran fine last night, after cranking the crap out of it to start.

    See my thread, I'd appreciate any helpful tips posted to it! :)

    http://www.ferrarichat.com/forum/showthread.php?t=392334
     
  15. F360-1386

    F360-1386 Formula 3

    Oct 8, 2006
    1,637
    Markham, ON, Canada
    Full Name:
    51216M
    If it was cranking, then it shouldn't be ignition coil module. If ignition coil failed , it would have no crank at all. Seems like a starter issue. You may try to push to start it using clutch then drive it to the shop to check it out .

    Sent from my SM-N910W8 using Tapatalk
     
  16. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    What did the ebay unit cost ?

    I think this is the same one here: http://www.motorcityreman.com/maoe065858.html
     
  17. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    That's not correct.

    The car will run with a faulty ignition coil. It just runs of 4 cylinders, as there are 2 coils. One for each bank.
     
  18. srephwed

    srephwed F1 Rookie
    Silver Subscribed

    Apr 29, 2012
    3,269
    street,md
    Full Name:
    fred brown
    This may or may not have anything to do with your problem but maybe it will help with mine. I have a QV that I installed a 328 long block and used all components from the QV. One thing I did during the swap was installed Nicks XDI ignition. Expensive,yes. Easy,yes. Worth it, Absolutely. No more Digiplex. No more distributor cap or rotor. No more plug extenders. No more flywheel sensors. What mine does is run Flawlessly 95% of the time. Once in a great while it idles slow, seems to be loading up then I leave a stop light and start going up in the gears and it will give a pop or backfire then run perfect again. Mine is a euro with no cats, no air pump, no o2 sensors, nothing. By the way I am not associated with Nick and his business in any way. Just a nice setup.
     
    thorn likes this.
  19. MvT

    MvT F1 Rookie
    Silver Subscribed

    May 25, 2013
    3,774
    The Netherlands - NH
    Full Name:
    Tijn
    Digging up this old post as I recently lost 300 to 400 rpm when having the engine running waiting for someone and when trying to pull away it looked like the handbrake was on. No rough idle just lost half the power.

    Back home I looked at the problem and narrowed it down to a broken ignition module. Taking off the module I notice the cooling paste totally dried up. So it is very good to check this before you burn up a module. Processor cooling paste is also fine to use.

    My 3.2 has the same module as Mike's (Magneti Marelli bkl 3ba), but these are hard to find and cost a fortune compared to what it does. It usually is also only shippen with a coil and its cooling bracket.

    I found a Hella module with the same specs, but can take somewhat more heavy AMPs then the Magneti Marelli one.

    Have fun with this one for $50.00 :)
    Hella 5DA 006 623-001

    I'll put it also on my cross reference list on my site:
    http://www.mymondial32.nl/part-cross-reference/

    Image Unavailable, Please Login
     

Share This Page