Burbling / Farting Sound from my 348 Spider | FerrariChat
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Burbling / Farting Sound from my 348 Spider

Discussion in 'Technical Q&A' started by marbro, Jun 1, 2011.

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  1. marbro

    marbro Rookie

    Jan 31, 2009
    14
    Calgary, AB, Canada
    Full Name:
    Mark Heber Brown
    #1 marbro, Jun 1, 2011
    I have a 1994 348 Spider with low mileage. I had a major service done about a year ago. Recently it has developed a burbling / farting sound barely perceivable in the exhaust note at neutral throttle and only at revs below 3750. It pulls hard and there appears to be no loss of power, but at cruise or low revs (below 3,750) is burbles and upon gentle acceleration it feels like it is missing slightly then it disappears altogether on hard acceleration. No loss in performance, just this annoying little burble that was not there a year ago.

    I have tried ECU reset procedure as per wkshp manual. no change. Still there.

    I have not pulled the spark plugs to check for build up, and I have no reason to suspect HT wires or connections.

    Any ideas?
     
  2. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,966
    Milton, Wash.
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    Jeff B.
    #2 Miltonian, Jun 1, 2011
    My idea would be that the anti-backflow valve on the exhaust air injection system is failing on one or both banks, and if so, it would be a good idea to correct it before it melts the rubber hose.

    Other ideas?
     
  3. 3forty8

    3forty8 F1 Rookie
    Owner

    Apr 25, 2006
    2,713
    San Diego
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    Eric
    #3 3forty8, Jun 2, 2011
    I used to get the burbling with a small miss at low RPM. It cleared up when I installed Dave's connector kit for the sensors and ECUs. Does it happen right from a cold start (i.e. open loop mode), after the car is warmed up in closed loop mode, or all the time?

    You may also want to unplug the connectors to major sensors (like the TPS, phase, O2, etc), clean the connectors with electrical contact cleaner and a wire brush and see if there is an improvement. So many gremlin type problems on these cars can be traced back to poor connectivity and the ECUs not getting the correct info from the sensors.
     
  4. robbie

    robbie F1 Rookie

    Aug 26, 2005
    3,015
    Los Gatos, CA
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    Robert
    #4 robbie, Jun 2, 2011
    Maybe it's that Burrito you had just before hearing the sound. :) (Sorry .. couldn't resist .. good luck with the diagnosis)
     
  5. marbro

    marbro Rookie

    Jan 31, 2009
    14
    Calgary, AB, Canada
    Full Name:
    Mark Heber Brown
    #5 marbro, Jun 2, 2011
    Thanks for all your replies. Most helpful.

    It only happends after full warm up. Upon start and while cold (oil temp not up to full temperature) the problem is non-existent.

    I suspect you are right about the connectors. It seems to me that my service specialist suggested I do the full Dave's gold plated connector treatment, but I passed because I am such a purist and I had just seen all the shiney new lookign connectors when I had the last engine out.

    Do you think the Stabilant 22 stuff will help?

    marbro
     
  6. Sledge4.2

    Sledge4.2 F1 Rookie

    Oct 19, 2007
    4,786
    Marin
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    Geno
    #6 Sledge4.2, Jun 2, 2011
    its the carbs. probably lean.
     
  7. marbro

    marbro Rookie

    Jan 31, 2009
    14
    Calgary, AB, Canada
    Full Name:
    Mark Heber Brown
    #7 marbro, Jun 2, 2011
    Carbs? It is a 348 we are talking here. Do you mean the MAFs? They apparently can be adjusted to 'thin out' or 'thicken up' the air to fuel ratio.
     
  8. Sledge4.2

    Sledge4.2 F1 Rookie

    Oct 19, 2007
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    Geno
    #8 Sledge4.2, Jun 2, 2011
    joking
     
  9. 3forty8

    3forty8 F1 Rookie
    Owner

    Apr 25, 2006
    2,713
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    Eric
    #9 3forty8, Jun 2, 2011
    It may help initially, but it hardens up over time creating a varnish and (in my experience) made matters worse. Dave's kit works - it's not just the fact the connectors are gold plated, the spec and tolerance of his connectors are vastly superior to OEM. The OEM connectors really are junk, only rated for 5 connects/disconnects.

    I'd rather be called a non-purist and have a car that runs properly. ;)
     
  10. marbro

    marbro Rookie

    Jan 31, 2009
    14
    Calgary, AB, Canada
    Full Name:
    Mark Heber Brown
    #10 marbro, Aug 13, 2011
    Finally solved this, or more accurately my local Ferrari specialist solved it.

    Turned out to be a very bad spark plug (electrode completed worn down).

    I had pulled one bank off and these were fine. Being lazy I did not pull the other bank. Then the weather got really good and all I wanted to do was drive my car, so a took it in to the garage thinking that would get me back on the road quicker.

    Anyways, they checked virtually everything and ruled everything else out. The car is running beautifully now with a fresh set of plugs.

    Have fun all!
     
  11. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,723
    Amsterdam
    #11 166&456, Aug 15, 2011
    Electrodes on spark plugs do not wear down all of a sudden by themselves. Has the cause been investigated? Do that before the damage is worse than just a plug. It could for instance be that the injector for that cylinder is bad and it's running lean.
     
  12. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,220
    Mount Isa, Australia
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    Pap
    #12 PAP 348, Aug 15, 2011
    Glad to hear it's sorted! Happy motoring. :):)

    I have seen this happen before with cheaper brand spark plugs.

    The customers supply the cheap plugs, we fit them. In 6, 12-18 months (whatever), they come back with an engine miss.

    We have seen it all too many times where one plug is almost worn completely out and the others are fine. I put it down to it being a **** batch of plugs when this happens. I have never been able to confirm the exact cause.

    I have also fitted new (cheap brand) spark plugs and have one dead from the get go. Or fit them and have the owner come back weeks later with an engine miss and I find the dead plug then.

    If you stick to the good brand spark plugs, you never have an issue. Maybe once I recall getting a dead NGK spark plug many years ago. Every other time has been smooth sailing.

    Would be nice to know what brand spark plugs were fitted to Mark's 348. :)
     
  13. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,723
    Amsterdam
    #13 166&456, Aug 15, 2011
    It would be a first for me to see that, hence my surprise. Knowing the plugs' brand would be useful information indeed, as well as if the damage occured after any hard use? Your post is reassuring but I still would be very wary of differences in the burn pattern between the cylinders on that bank.
     
  14. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,220
    Mount Isa, Australia
    Full Name:
    Pap
    #14 PAP 348, Aug 15, 2011
    Absolutely, would be nice to know what plugs he had/has in there and the condition of all the old plugs. Especially from the bank/cylinder with the worn plug. :):)
     

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