Fighting a misfire issue Fiat Dino 2.4L | FerrariChat

Fighting a misfire issue Fiat Dino 2.4L

Discussion in 'Technical Q&A' started by eastwest7, Apr 11, 2021.

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  1. eastwest7

    eastwest7 Karting

    Oct 1, 2014
    119
    roseville,ca
    Hi all, hoping for some help with a misfire issue on my 2.4L Dino. #2 cylinder is not lighting off. Ive done the obvious. New NGKs, compression while a bit low was 120-125 on all cylinders. I assume its getting enough fuel since the plug is wet after running for a bit. I am getting spark to the plug. Swapping wires and plugs in that cylinder changes nothing, its specifically not firing on #2. Im lost now. Its an older engine and has been sitting for a few months but cant figure out why its not hitting on the cylinder. Any advice would be great. Trying to figure it out before I decide to have someone else take a look.
     
  2. wmuno

    wmuno Formula Junior
    Silver Subscribed

    Dec 24, 2007
    430
    Wilmette, Illinois
    Full Name:
    Bill Muno
    If the plugs and wires are OK, the next things to look at are the distributor cap (hairline cracks?), rotor, points, condenser, and coil.
     
    nini likes this.
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,038
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Are you saying that there is no spark detected occurring in the #2 spark plug wire with a timing light?
     
  4. eastwest7

    eastwest7 Karting

    Oct 1, 2014
    119
    roseville,ca
    I dont see any obvious problems with the ignition system. There is spark going to the #2 cylinder. I confirmed it with a timing light and the wire is arching when I have it off the #2 plug.
     
  5. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    19,344
    The Cold North
    Full Name:
    Tom
    I would be double checking the compression of that cylinder. If it checks out ok..next step would be a running compression test. You may have a broken valve spring..
     
    2NA likes this.
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,038
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Can you give some more background information please:

    Are you saying:

    A - it was running fine, stored for a few months, and now it has this issue (i.e., it went from running OK to having a problem with no one doing anything at all).

    or

    B - you are resurrecting the engine from an unknown past, and it's always had this trouble (i.e., you don't know who's done what to it since it last ran OK)?

    Does it do this at all engine speeds -- both idle and higher RPM -- or just at higher RPM?
     
  7. eastwest7

    eastwest7 Karting

    Oct 1, 2014
    119
    roseville,ca
    Thats the problem with letting things sit. Im confident that I got this car running without a miss last summer but exactly how great....i dont remember. This car has been sitting for a solid 7 months and hasnt been driven much at all in years.

    It is missing at idle and at lower engine rpms. A dead cylinder type of miss, every time. In the upper rpm range it smooths out, but I think its still missing. It hard to tell with the upper rpms 3-4k because I think the engine sounds like its naturally balancing its self out if that makes sense.

    When I got home I pulled the plugs and cranked the car over with the wires still attached. They all had the same quality spark even on the dead #2 cylinder. Thinking about a possible broken valve spring, Im going to borrow a scope camera from a friend, turn it over and see if I can see the valves open up. I have confirmed no vacuum leaks as well.
     
  8. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    Are you running on fresh fuel or from left over of the 7months old storage? Have you also checked the ignition timing?

    These are easy tests I would perform before dropping the cylinder heads...
     
  9. Hocakes

    Hocakes Formula Junior

    Apr 24, 2010
    451
    FL
    Old gas doesn't magically go bad in only 1 cylinder.
    Sent from my Samsung Note 8 using FerrariChat.com mobile app
     
  10. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    On my distributor tester I've seen up to 3degree difference between cylinders. Coupled with bad fuel, this could cause a rough idle that would have otherwise been unnoticed.

    At higher rpm the advance kicks in,
    which could explain why his engine seems more balanced.

    As said, I' d rather make a diagnostic with clean fuel. Seems reasonable before removing the camshafts (?)
     
  11. eastwest7

    eastwest7 Karting

    Oct 1, 2014
    119
    roseville,ca
    I will add some fresh fuel and recheck timing before digging into the engine. This weekend I am putting a scope down the cylinder to see if the valves are moving.
     
  12. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,772
    So it revs up and smooths out? That sure sounds like a plugged idle jet?
     
  13. Andy 355

    Andy 355 Formula Junior

    Jun 2, 2013
    434
    Sydney
    Check the firing order.
     

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