456 black exhaust smoke under load and other issues | FerrariChat

456 black exhaust smoke under load and other issues

Discussion in '456/550/575' started by Alexander฿, Apr 23, 2021.

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  1. Alexander฿

    Alexander฿ Rookie

    May 18, 2019
    14
    Full Name:
    A Mardenborough
    Hello,

    Long 420 mile trip today in my 95 456, returned home to find my bumper covered in a lot of soot. Particlarly one side.
    Saw for myself looking in the mirror with some WOT runs including standing behind the car as a friend prodded the gas..
    No missing or surging under WOT.

    Noticed under small constant throttle openings there's some slight infrequent kangarooing/surging at motorways speed crusing.
    I have this situation more frequently on a cold start ups which gradually reduces when warming up.
    Revs on start up are sometimes low enough to bog and die, second time firing revs naturally rise to normal 1300-1200 cold start revs. Have to say this didn't happen before this major.

    Car had a major 1000km ago and started to have these issues since then, haven't had this soot issue before.

    New x2 179278 control station units too that Ratarossa recommend from NZ.


    Worked out my MPG from today's trip at mainly motorway 75-80mph.
    14.4 litres per 100km or 19.51 MPG...
    Any ideas to check?

    Best Alex


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  2. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Dirty/dripping injectors can cause the cold start problem, but sounds like an ignition problem for the other part. If that mpg is Imperial gallons (1.201 US gallons = 1 imperial gallon), that sounds about right.

    If ignition diagnosis does not find an issue, a compression and bleed down to check valve guides might be in order. Odds are, though, something was not hooked up properly at the belt change.
     
    Fennicus and brogenville like this.
  3. Alexander฿

    Alexander฿ Rookie

    May 18, 2019
    14
    Full Name:
    A Mardenborough
    Thanks for that, checking around ignition today and will report back.
     
  4. Salami

    Salami Karting

    Oct 31, 2020
    219
    Oregon
    I’d look at your connectors also, especially the MAFs. Did you have any CELs?
     
  5. Alexander฿

    Alexander฿ Rookie

    May 18, 2019
    14
    Full Name:
    A Mardenborough
    Little update.
    Checked all connectors with contact spray. Did have some kind of gel on the MAF connectors see pic attached.

    Also swapped out those NZ company cat ecu's for my originals. Bought them to help clear a flickering of the check engine 7-12 light that randomly flicks on for a split second when the aux fans turn on. (Didn't cure.)
    Set out to drive to DK engineering in the UK to have a look at this smokeness and the dreaded drivers seat which is playing up which is fixed in the gangster lean position..

    Noticed no smoke or hesitation on the 120mile drive. Hmm. Could it be those aftermarket cat ECU's?
    Will back to back once I get her back and DK has a good check over too.


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  6. Salami

    Salami Karting

    Oct 31, 2020
    219
    Oregon
    Well you committed the sin of changing more than one thing at a time so we are only guessing now. I’d suspect it was the connector work you did that cleaned things up. Of course, it was also my idea so I would tend to like it best.
     
    franschman likes this.
  7. Alexander฿

    Alexander฿ Rookie

    May 18, 2019
    14
    Full Name:
    A Mardenborough
    Second update.

    She's running rich confirmed by DK due to one of the three temp sensors not functioning correctly. Changing all. (Didn't know there's 3) inlet has to come off so the coolant hoses underthere will be changed too for piece of mind.
    Seat issue was the potentiometer.
    Collect next week. :D
     
    white out and Fennicus like this.
  8. Robbe

    Robbe Formula Junior

    Aug 22, 2013
    609
    The Netherlands
    There are 3 coolant sensors located under the manifold, but one is for the cabin meter and when that one is broken, you would see it on the temp meter...
    I have not heard much about that one failing, but replacing it while you are in there is not unwise.
    Then there is the intake air temp sensor, which is, you guessed it, on the intake system (airbox).
    That one you can easily change yourself, 5 minute job.
     

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