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ignition problem on 328?

Discussion in 'Technical Q&A' started by Dutchman, Mar 14, 2004.

  1. Dutchman

    Dutchman F1 Veteran
    Lifetime Rossa Owner

    Dec 4, 2002
    6,180
    EU
    Full Name:
    Ton
    Hi Guys,

    I need your help. Yesterday I started my 328 to take her for a drive and I already noticed after a couple of minutes that the engine was not running properly. Every now and then there is a short fall in RPM. I took her for a drive to warm up the engine properly but during the drive the car holds back (rather firm) regularly and sometimes there is a loud bang out of the exhaust. Even with a hot engine the car acts the same. Is this an ignition problem? Or is it a fuel problem? I cleaned all the plugs on the Magnetti Marelli ignition system and removed and reinstalled the sparkplug cables. But the problem stays the same.
    What should I do?

    Thanks

    Ton
     
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  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    20,499
    Texas
    Full Name:
    Steve Magnusson
    Give more information? ;)

    You've got to start lopping branches off of the tree.

    I understand the actions you've taken, but does that mean you've actually verified good spark ignition is occuring on all 8 spark plug wires over the RPM range where you're noting changed behavior? If so, then you should direct your attention elsewhere; but otherwise, I'd say that branch is still possibly "open".

    Is cold-running now also degraded/changed? (Lambda-equipped K/KE are a little stupider/simpler during cold-running mode.)

    One thing I'd try as a first sniff is to measure the voltage behavior on the O2 sensor output wire for maybe 5~10 seconds (long enough where you should see some voltage change if it's truly running in closed-loop mode) and maybe both at idle & 2~3K RPM in two conditions:

    1. warm-running with the O2 output wire plugged-in (closed-loop mode)

    and

    2. warm-running with the O2 output wire unplugged (open-loop mode)

    If you've got a single-cylinder-type problem these O2 voltage measurements might not show much, but it's an easy place to get a first peek into the injection system IMO.

    Good hunting...
     
  4. TOM B

    TOM B Formula 3

    Jul 24, 2003
    1,038
    Orange County, NY
    Full Name:
    Thomas Buckley
    Ton,


    The symptoms you describe could be caused by a bad sparkplug extender. These are the long, plastic towers that connect each sparkplug to its wire. Sometimes the offending extender will only show a burn mark on the outside the size of a pinhole. Other times, the burn mark can be much larger. The key is that the burn mark on the outside will extend through the plastic to the inside of the extender. When this happens you have a misfiring cylinder .

    I hope this helped. Let me know if you'd like me to post pictures of some bad extenders for illustration.

    Tom
     
  5. Dutchman

    Dutchman F1 Veteran
    Lifetime Rossa Owner

    Dec 4, 2002
    6,180
    EU
    Full Name:
    Ton
    Tom,

    Can you show me a picture of a bad extender? I looked at them all today. Nothing really drew my attention.

    thanks,

    Ton
     
  6. cinquevalvole

    cinquevalvole Formula 3

    Feb 6, 2004
    1,151
    Germany, Bayern
    Hi Ton,

    this could be a bug inside the spark plug.
    When this happened to my 328 GTS we changed all 8 and could see that
    spark plugs from cylinder 5 and cylinder 8 were in bad condition (too dark).
    With bugfree sparks the car was running smoothly again for another 10.000 km.
    My mechanic said:
    Cleaning the spark plugs won't be a proper solution in every case.
    Sometimes the spark plug is destroyed/buggy inside what you can't see on it's surface.
    Sometimes it sparks, sometimes not. It has it's own will. (LOL)
    You can sort it out by changing just on the rear bank (4 sparks) as a first step.

    good luck

    cinquevalvole
     
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  8. TOM B

    TOM B Formula 3

    Jul 24, 2003
    1,038
    Orange County, NY
    Full Name:
    Thomas Buckley
    Ton,
    My wife is on a road trip in Canada and I think she took the digital camera with her. She'll be back tomorrow so I should be able to shoot some pictures and post them in the evening. OK ?


    Tom
     
  9. Dutchman

    Dutchman F1 Veteran
    Lifetime Rossa Owner

    Dec 4, 2002
    6,180
    EU
    Full Name:
    Ton
    Thanks Tom!

    I will check again tomorrow.

    Cinquevalvole,

    Thanks for your input. I will change the sparkplugs and let you know what the result is.

    Ton
     
  10. theo-m

    theo-m Rookie

    Dec 26, 2003
    35
    Very common. You have a bad wire or connector. It is probably time to install new as well as new rotors and caps. You are then good for years.
    Theo
     
  11. KurtK328

    KurtK328 Formula Junior

    Mar 6, 2001
    347
    Villeneuve-Loubet, France
    Full Name:
    Kurt Kjelgaard
    A couple of years ago I had the same problems with my 328.
    New wires (all 10) took care of it.
    If you measure the resistance for the spark plug wires you will
    probably notice some or all have indefinite resistance.
    The car will still run, but intermittently you will have a misfire.
    Make sure that your wires are fixed in the black plastic holders,
    as they seem to be sensitive to vibrations. The conductor in the
    (original) wires consist of a cord "soaked" in graphite powder and
    apparently something happens to this over time.
    I also changed the extenders as they looked a bit shady.
    Be sure that you get the correct parts (red for the 328) as there are
    different radio suppression characteristics for different partnumbers.
    The black extenders in my mix of extenders were also a little bit shorter.
    The "disks" on the original silicone sleeves could not be pursuaded to
    stay fully on the extenders when pressed down on them, but tended
    to pop up to their normal position in the valve cover, making the
    connection with the extender less than optimal.
    Finally, there are several threads on this from earlier times, also check
    the early FChat forum archives
     
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  13. jarends

    jarends Formula Junior

    Jul 23, 2001
    567
    Princeton, NJ
    Full Name:
    John Arends
    Hey Ton,

    Sounds like a bad dream. My wife's started that last year and got progressively worse. I've ask this question on the TEch thread before and got the same answers.

    HIstory: (I hope you don't go through this)

    first: $2600 New cap/rotor and tuneup (worked all the way home and the next time I started it, same thing).

    Second: towed from Matt's place in Flemmington after a good ride all morning (around 100 miles) and then when started after lunch, missing like mad). New mechanic picked it up and said it was the fuel filter, fixed and did I don't know what and bang another $2500. Rode home great. Next startup, no go, same thing. (Now 5000+ into the problem)

    Third: Same shop picks it up and after nineteen hours of work ($2100) said he didn't know what was wrong, but it's running fine now. (It isn't, surges at idle and the pedal is soft)

    I'm tired of it and intend to do my own work before my wife sells the car in disgust.

    Let you know,
    J
     
  14. TOM B

    TOM B Formula 3

    Jul 24, 2003
    1,038
    Orange County, NY
    Full Name:
    Thomas Buckley
    #11 TOM B, Mar 15, 2004
    Last edited by a moderator: Sep 7, 2017
    Ton,

    I don't take very good close-ups but I think this picture illustrates the point. The extender on the right has a very obvious burn - through. The one on the left, though not as obvious, is also burned through. I hope this helps. If not, please e-mail me and we'll work it out. Good luck.


    Tom
    Image Unavailable, Please Login
     
  15. jarends

    jarends Formula Junior

    Jul 23, 2001
    567
    Princeton, NJ
    Full Name:
    John Arends
    Tom do you think a first class mechanic would miss a simple spark through like your showing. Gus found one in his blue 328, but I didn't check for that.

    Would the problem be intermitten? Anyway, would one extender intermittenly cause the engine to run that rough. It just doesn't make sense.

    Oh well, I might never know
     

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