Calling 348 gurus. idling problem | FerrariChat
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Calling 348 gurus. idling problem

Discussion in '348/355' started by SFchallenge, Nov 8, 2005.

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  1. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
    11,945
    Sgp, KL, HK & London
    Full Name:
    Jon Wijaya
    #1 SFchallenge, Nov 8, 2005
    Alright, my 348 is @ it again. It's a 1990 model. Just had a 30K major done with new fluids, belts, clutch, MAF meters, fuel lines, fuel filters, starter motor, K & N filter etc. My ECUs are good & I've tried the battery cut off & "learning" period. Compression is good.

    The problem: on every cold start, the car will idle well & then starts to fluctuate after 3mins+ & so bad it kills the engine. It'll then be difficult to start & I need to hold the accelerator to maintain the rpm for a few minutes till it's stable. This can be a headache if I need to leave immediately & dangerously as the car can just die off after leaving carparks which I need to play between the accelerator & clutch/brake. It's OK when it's warm & pulls strongly. No backfire.

    My mechanic said it's probably due to worn injectors & seals or maybe they're just dirty. The mixture is rich, a lot of unburnt fuel. It's running 800-800 parts/million. New injectors are going to cost me US$1500. My question is: is it injectors or something else? Eg. water vapour in fuel tank/lines, wrong plugs or whatever.

    Finally, does those fuel injector cleaners help or do more harm? Thanks. Jon
     
  2. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,223
    TN
    #2 308GTS, Nov 8, 2005
    I would be surprised if it the injectors. Have you verified spark on boths sides of the engine when this condition is present? If spark is present on both side then I would look at the fuel pressure regulator. If that was ok I would check your Mass Air Sensors. If you have a fuel pressure gauge it would be a good idea to check your fuel pressures. Let us know what you find out. This way if someone else has this problem that can see the repair when they pull up this thread.
     
  3. BT

    BT F1 World Champ
    Lifetime Rossa

    Mar 21, 2005
    15,291
    FL / GA
    Full Name:
    Bill Tracy
    #3 BT, Nov 8, 2005
    The idle adjustment is done on both sides of the engine intake. You loosen the retaining nut and then adjust the idle set screw and then retighten the retaining nut. It may have been adjusted differentially (more on one side than the other). My mechanic (Tim Stanford) told me that you can get uneven idle if both sides are not set exactly the same. I don't know how to reset it to factory (how many turns), but someone else here may chime in with that info.
    BT
     
  4. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
    11,945
    Sgp, KL, HK & London
    Full Name:
    Jon Wijaya
    #4 SFchallenge, Nov 8, 2005
    Forgot to mention that my mechanic was a workshop manager with UK's Maranello (Ferrari agent). So, he should know the factory adjustments but I'm sure there's more things you guys know. I was told my car is 15yrs old & the hot & humid climate's not too good.

    My Mass Air Sensors are new. Bought them off Rockauto, I still don't know how to use the multimeter on them to get the 263 ohms. "NO doubt"?

    Fuel regulators, I haven't tried them! How can we check this? I wanted to install the gauges on the fuel lines but was worried about leaks=engine fire.
     
  5. chrisx666

    chrisx666 Formula Junior

    Dec 6, 2004
    562
    YorkshireUK
    Full Name:
    Chris B
    #5 chrisx666, Nov 8, 2005
    Last edited by a moderator: Sep 7, 2017
    Might be as simple as a bad connection somewhere, I'm not sure the "it's old, what do you expect?" argument helps much. There is a diagnostic section in the worksop manual that starts like the picture below and goes on the check oxygen/coolant sensors etc. etc.

    The resistance of the MAF's is pretty easy to check. You need to set your multimeter to read 'ohms' (doubt if the &#61527; symbol will post, it's like a curly n). Multimeters normally show OL (off scale) with the probes apart and near 0 (<5) ohms when touched together.

    Turn off ignition. Disconnect the MAF cable and place one multimeter probe on each outermost connector pin (1+6? MAF side, not loom). The base value is 383&#61527; IIRC – I checked mine for the fun of it and they were exactly that.

    Try here for more..

    http://www.ferrarichat.com/forum/showthread.php?t=75815&highlight=348+MAF
    Image Unavailable, Please Login
     
  6. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,614
    The Brickyard
    Full Name:
    The Bad Guy
    #6 ernie, Nov 8, 2005
    Have you pulled the codes yet? Even if you haven't gotten a check engine light there are others codes that get stored silently. Try pulling the codes first to see what ecu's have stored.
     

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