Should the idle be 'silky' smooth (F355)? | FerrariChat
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Should the idle be 'silky' smooth (F355)?

Discussion in 'Technical Q&A' started by racer17, Aug 28, 2006.

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  1. racer17

    racer17 Karting

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    #1 racer17, Aug 28, 2006
    Guys...have a '97 F355 with Tubi and hyperflows installed. All else is stock. Been driving it now for about 3 weeks and starting to notice the 'small' details. At idle (hot and cold) the car runs a solid 1000RPM. If you listen real close, every 2 or 3 minutes there may be a slight change in pitch/sound/resonance of the idle for about a second (or even less). Not a dip in RPM necessarily, but more of a 'burble or gurgle' in the exhaust note (maybe the RPM is dipping for a slip second, just not being recorded on the tach). I know its hard to describe the sound, but just wondering if these cars should have a constant silky smooth hum to them all the time at idle? My M3 does, but it is a 2005 vintage with oodles of technology all over it.

    I should mention that with a load on the car at 4-5K, never misses a beat. As well as hard acceleration, car is steady and strong right to red line on all shifts.

    Your experiences with what a smooth idle should sound like in an F-car?
     
  2. PaulK

    PaulK F1 Rookie
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    #2 PaulK, Aug 28, 2006
    I don't own a F355 yet but it sounds normal. Have you posted pics of your car in the F355 pics thread in the 348/355 section? You should if you have not! ;)
     
  3. johan6504

    johan6504 Formula 3

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    #3 johan6504, Aug 28, 2006
    My 355 GTS F1 -98 has a slight misfire on idle, I can hear it when the engine is hot. The misfire was a lot worse as I got the car but the engine runns better the more I drive it, alomost gone now after the summer.

    The sound you describe makes me think of the change in engine sound as the fans start. When tha fans starts (or AC) on my car I can hear a slight drop in rpm for a second much as you describe it.
     
  4. racer17

    racer17 Karting

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    #4 racer17, Aug 28, 2006
    Last edited by a moderator: Sep 7, 2017

    That could definitly be it. I hadn't put 2 and 2 together on that one yet.

    I would assume that a true misfire (bad plugs, wires) would be real apparent under heavy load/acceleration?

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  5. PaulK

    PaulK F1 Rookie
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    #5 PaulK, Aug 28, 2006
    I love it. I remember it from the other thread. Hasn't got old though ;)
    Thanks.

    PJK
     
  6. Vivid

    Vivid Rookie

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    #6 Vivid, Aug 28, 2006
    Sounds normal. If there is a random misfire, the ECU will throw the CE light. I wouldnt worry about it.
     
  7. rmfurzeland

    rmfurzeland Formula Junior

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    #7 rmfurzeland, Aug 28, 2006
    I hear a similar blip in the idle in my 550, I have always assumed this is normal and due to the feedback loop of the emissions sensors and the ECU, always constantly adjusting and any small delay effects. I believe with fuel injected ECUs its hard to get it perfectly stationary like you can with a carburetted car.
    I notice it on non Ferrari cars too. The effect is more noticeable on a Ferrari since the idle is often higher than most other cars and the exhaust note (and its change) is more obvious.
    Ron
     
  8. racer17

    racer17 Karting

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    #8 racer17, Aug 28, 2006
    Hey thanks a lot fellas for chiming in here. It's my first F-car (and loving it), and I am still slightly paranoid....getting more comfortable with every drive!
     
  9. F355 Spider

    F355 Spider Formula 3

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    #9 F355 Spider, Aug 28, 2006
    I've got a '97 Spider and have the same thing so I wouldn't worry about it... By the way has your check engine light come on yet??? Don't want to jinx you if it hasn't but that is a fun one chase around...

    Sonny.....
     
  10. racer17

    racer17 Karting

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    #10 racer17, Aug 28, 2006
    Nope....she runs tight!!
     
  11. Lagerlout

    Lagerlout Formula Junior

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    #11 Lagerlout, Aug 28, 2006
    Yep it's closed loop mode, very noticeable in older injected cars.
     
  12. Llenroc

    Llenroc F1 Veteran
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    #12 Llenroc, Aug 28, 2006
    As an extention of what is said above the ECU at idle is using the 02 sensor to keep the A/F mixture at 14.7:1. the ECU will alternate the mixture back and forth(rich/lean via the reading from the 02 sensor) and in that process you get occasional slight miss. If you unplug the 02s the miss goes away but then you won't be omissions compliant and you CELs will come on. Regards, Vern
     
  13. Monteman

    Monteman Formula 3
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    #13 Monteman, Aug 28, 2006
    My 98 does the same exact thing and always has. Nothing to worry about, it's normal.
     
  14. RayJohns

    RayJohns F1 Veteran
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    #14 RayJohns, Aug 29, 2006
    I had a 97 355B and it did the same thing. Keep in mind the 355 has a nasty habit of developing a hole in the headers, and that can affect the idle (usually making it louder). If you start hearing a ticking noise, you may have a hole developing. But as I recall, my 355 would throw out a little up/down change to the idle tone every so often as well.

    Ray
     
  15. davey_jones

    davey_jones Formula Junior

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    #15 davey_jones, Sep 7, 2006
    Yep, just like the others said Verns got it on this one too.
    Good explanation too. I drove myself nuts trying to figure it out as well.
     
  16. gothspeed

    gothspeed F1 World Champ

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    #16 gothspeed, Sep 7, 2006
    Yep, my 355 seems to run better and better the more I excercise it too. :) A slightly uneven idle sounds normal, especially when the fans kick in.

    The fans draw more current when starting and put more load on the alternator. Which in turn transfers the load to the engine.
     
  17. jm3

    jm3 F1 Rookie

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    #17 jm3, Sep 7, 2006
    My car is one of the best idling f355's I have been in.
    I made it even better, almost BMW like, by:

    Unclipping the airflow meters (1995). Spraying electrical parts cleaner all over the hot wires inside, about 6 seconds worth. Not carb cleaner

    Disconnect battery at switch.

    Let sit 1/2 hour.

    Reconnect airflow meters

    Reconnect battery.

    Start and let idle for 10 mins with no blipping or a/c.

    It just idles better now, dead steady at 1000 rpm, 3 weeks later.

    Jay
     

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