F355 2.7 Test Pipe Install Questions

Discussion in '348/355' started by PaulK, Aug 7, 2018.

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  1. PaulK

    PaulK F1 Rookie
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    That isn't bad actually when compared to the actual Ferrari SD tool. You would have thought by now that someone would make an open source one that just uses a laptop.

    But does the Galileo tool do everything the SD one does?
     
  2. F355Bob

    F355Bob Formula 3
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    I had piggy back computers to control fuel and timing. I would foul plugs all the time. When the tuner tuned it, he took a bunch of fuel out of low end and much better throttle response and much better low end power. It's not normal to foul plugs on just starting, these cars run rich. Jim are you thinking Motec?
     
  3. INTMD8

    INTMD8 F1 Rookie
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    I'm thinking Halltech or Pro EFI so far. Motec requires you to purchase "upgrades" I feel should be part of the system to begin with.
     
  4. Yassa

    Yassa Formula 3

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    I have test pipes instead of cats and y pipe... The car is loud and stinks and you get flames out the tail pipe.
     
  5. johnk...

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    Fuel trim does not tell you if the car is running rich or lean. It tells you what the O2 sensor sees and what the ECU is doing, adjusting LTFT, to try to make lambda correct. I.e., if the O2 sensor consistently see a lean condition (lambda > 1), the ECU will move LTFT (+) to get lambda back to about 1.0.

    Never had a problem fouling plug on my 95 in 5 years, 9k miles.
     
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  6. INTMD8

    INTMD8 F1 Rookie
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    Yes this is correct however if you have an exhaust leak driving fuel trims positive the engine will actually be running richer than lambda.

    So still good to see if there's anything abnormal with the fuel trims and if so find the reason why.
     
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  7. johnk...

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    Yes, I was assuming everything else is order. Excessive LTFT is an indication of a problem. Could be a bad MAF giving wrong air flow; a fuel pressure problem; intake leak; O2 sensor switch point drift. LTFT will correct for them. On the exhaust side, yes, exhaust leak before the O2 sensor can result in over rich because that air is not going into the cylinders. Also a miss fire can cause a rich condition because the O2 sensor reads excess O2 in exhaust.

    But I agree, excessive LTFT is an indication of a possible problem, though not necessarily a rich or lean condition, depends on where the problem is.
     
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  8. F355Bob

    F355Bob Formula 3
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    Do let your car warm up past the enrichment mode before you shut it off?
     
  9. johnk...

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    #34 johnk..., Aug 8, 2018
    Last edited: Aug 8, 2018
    Depends on what I'm going to do. Sometime I just back it put of the garage and shut it off. And actually, it runs smoother at idle before it goes into close loop mode. Once it's in closed loop mode it leans out and it will occasional miss at idle. Seems to be typical of a 2.7 car. They don't always idle that smoothly, but the rev like banshees. :)

    The more I read about 355s here the more I think mine is an odd ball.

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  10. Dave rocks

    Dave rocks F1 World Champ
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    Well true but the correction gives you clues to the condition prior to correction - correct? So it seems it points you in a direction for investigation.
     
  11. johnk...

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    Unless there is something wrong, it's just an adjustment. If you get a CEL and it says LTFT, then you have some clues as to where to look. In the simplest sense, LTFT is sort of like adjusting the idle mixture on a carburetor and short STFT is like the accelerator pump. Here is a quote from a BMW doc I have. Note the equivalence of LTFT and Additive value and STFT and Multiplicative values as with 5.2 and 2.7 cars.



    Q: What is “Fuel Adaptation” and what is “Fuel Trim”?


    A: “Fuel Adaptation” is the fine tune control of fuel delivery by the ECU. To accomplish this the

    ECU increases or decreases fuel delivery by increasing or decreasing the time that the

    injectors are open. The amount of this adjustment is known as the “Fuel Trim”. The fuel trim

    values over a range of engine speeds are known as the “Adaptation Values”.

    The ECU modifies the injection rate under two areas of engine operation. These areas are the

    idle or low load mid range engine operation and operation under a normal to higher load when

    at higher engine speeds. These altered injection rates are known as Long Term Fuel Trim

    (LTFT) Additive and Short Term Fuel Trim (STFT) Multiplicative. See figure 1.


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  12. johnk...

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    #37 johnk..., Aug 9, 2018
    Last edited: Aug 9, 2018
    Here is the doc. You might want to read it and in particular the last section, Rear O2 sensor fuel trim to understand why you should not run test pipes.
     

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  13. johnk...

    johnk... F1 Veteran
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  14. PaulK

    PaulK F1 Rookie
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    You guys are freaking me out!

    The car fouled the plugs because it was a cold start backing it out of the garage to wash it, and it was turned off. Wouldn't it be running rich on a cold start to act as a choke?
     
  15. Dave rocks

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    I found these videos to be very informative regarding fuel trims:



     
  16. Dave rocks

    Dave rocks F1 World Champ
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    Yes, I believe the ECU of all cars deliver more fuel on cold starts. You should hear my Maserati GT start "VOOOOORRRMM!!!!"
     
  17. PaulK

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    Thanks Dave!
     
  18. F355Bob

    F355Bob Formula 3
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    They deliver more fuel in the cold enrichment but mine was excessive. It would easily foul a plug if you cold started and then shut it off. A guy in my town had a 355 several serial # above mine and he routinely fouled plugs. A large amount of fuel was programmed out of it and has not been a problem since. These cars also have a weak spark and spark firing two plugs which doesn't help. Next mod will be coil on plug. I know there are old posts but any new insight on COP for the 355?
     

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