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95 F355 acting up but no codes again?

Discussion in '348/355' started by Orange Crush, Aug 31, 2017.

  1. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
    Full Name:
    Rob
    Went out to start the 355 and when I started it up it stumbled a little bit and then ran a little bit rough but cleared up. After letting it warm up a little bit I drove around the block and coming to stoplights when I put the clutch in the idle would hang around 1500 to 1700 And then drop back to 1000 after a few seconds. I didn't notice a loss of power but I did notice what could be a bit of a change in the tone of the exhaust. It also smells like it's running more rich but I do have a Capristo stage III and hi flo cats. Any thoughts on where to diagnose? Hasn't thrown a CEL or SDL in months and I just replaced the O2 sensors and one thermocouple a couple months ago. It definitely feels like it's running rich down in low rpm but clearing up in higher revs? Thanks for any direction!
     
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  3. Dave rocks

    Dave rocks F1 World Champ
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    Perhaps a plug / wire / coil. If you are not getting spark, you would have un burnt fuel and rough running.
     
  4. fatbillybob

    fatbillybob Two Time F1 World Champ
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    sounds like not running on all cylinders...could be even whole bank dead.
     
  5. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
    Full Name:
    Rob
    It's definitely not a whole bank dead, that has happened to me before and it was far worse than this. It still revs smoothly just stumbles a little under 2k and fine over that. I'm dreading the hole in the header as the culprit but I would think tone change plus more exhaust smell and weird idle might be just that?
     
  6. Dave rocks

    Dave rocks F1 World Champ
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    Don't think a hole in the header would cause a stumble. But, we aren't there to feel the "stumble"
     
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  8. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
    Full Name:
    Rob
    It's only when the car is idling and if in neutral. If I blip the throttle, right on tip in it just stumbles for a second at 1100-1200 and then revs fine. Sometimes it's accompanied by a light squeal which goes away when the hiccup occurs down low.
     
  9. eyboro

    eyboro Formula Junior
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    May 30, 2004
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    Eitan
    I bet it's the throttle position sensor, you need to remove it and clean it or replace it,
     
  10. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
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    Rob
    Where is it on the car and what is best to clean it with?
     
  11. eyboro

    eyboro Formula Junior
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    May 30, 2004
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    This is the part #158170, on the 95 355 there are 2 of them. You will have to remove the air intake to gain access, take a look at the diagram https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/355-group/f355-m2-7-1995/throttle-holders-and-controls/158170-potentiometer.html it's a very easy job, should not take more than 30 minutes.

    I paid $27 for a new one, but cleaning it with this item CRC 05111 Mass Air Flow Sensor And Throttle Body Intake Cleaner, should do it.
     
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  13. m.stojanovic

    m.stojanovic Formula 3
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    You can only clean its 3 pins. If this does not help, connect an ohm-meter to 2 of the 3 pins (find out across which 2 pins the resistance varies with the opening of the throttle). The resistance should change smoothly as you move the throttle. If there are any breaks in the resistance variation (especially while you move off the idle), the sensor is bad and you need to replace it. An analogue ohm-meter is much better for this test.
     
  14. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
    Full Name:
    Rob
    Great! I will give this a try, thanks guys. I read an older thread where some similar symptoms ended up being cam timing off just a bit. If that were the case it wouldn't just pop up out of nowhere correct? I would think it would have had to have been off since the last major and this car has been fine for a few years since?
     
  15. ssnowball

    ssnowball Formula Junior

    Oct 28, 2013
    251
    Orange County CA
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    Scot
    Just a thought, check your ignition wires. I experienced a similar condition and found that the bottom side of one of my wires must have come into contact with heat and was slightly melted.
     
  16. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
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    Wichita KS
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    Rob
    Update!

    Mechanic tested both O2 sensors and the passenger one was reading nil to dead. Driver side was good. He swapped both O2 sensors and it stayed bad on the passenger side!?!? What could cause this?
     
  17. Dave rocks

    Dave rocks F1 World Champ
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    Wiring
     
  18. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
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    This is why sometimes you need an SD 2, a breakout box, or some positaps. So you can actually see what signal is reaching the ECU.
    What stayed on the passengers side? You said there were no codes of CELs. So how do you know it's the passengers side? Part of the story is missing here.

    Also, hard to believe an O2 sensor was dead and no code or CEL. Could be the mechanic damaged the sensor when he removed/tested it. Once reinstalled the O2 code/Cle would take a while to come on unless it was the heater circuit that failed.
     
  19. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
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    Rob
    There was a code stored in the computer but the CEL never came on, that's how he knew to check the o2 sensor. Not sure why it didn't trip the light?
     
  20. Dave rocks

    Dave rocks F1 World Champ
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    What year is the car? If 96 and up (OBDII) will have pending codes
     
  21. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
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    Rob
  22. Dave rocks

    Dave rocks F1 World Champ
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    Apologies as I see the thread title has 95 in it.
     
  23. taz355

    taz355 F1 Veteran
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    Feb 18, 2008
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    Maybe cel bulb is taken out I know people have done that. If it lights with key on then its good.
     
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  24. johnk...

    johnk... F1 Veteran
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    What was the code?
     
  25. steved033

    steved033 F1 Rookie
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    that was my thought.

    sjd
     
  26. Orange Crush

    Orange Crush Karting

    Dec 30, 2009
    85
    Wichita KS
    Full Name:
    Rob
    Spoke to my mechanic and he said the driver side kept a 1211 code and the passenger side a 1114. Lights didnt trip and bulbs do work as the CEL's come on when i start the car for a couple seconds and then go out. He ran a temporary wire to see if the wiring was an issue direct to the o2 sensor and that did not cure it either. Does the ECM need codes cleared before it will talk to the o2 sensor again?
     
  27. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
    8,685
    New England/FL
    1114 is bad O2 sensor. 1211 is Lambda control. Typically a bad O2 sensor. However,

    "This code is stored when the DME detects excessive

    deviations in the air-fuel mixture (too rich or too lean) for longer

    than 10 seconds. Possible causes: Fuel tank ran empty,

    Incorrect Fuel Pressure, Injector valve defective or coked,

    Engine Temperature Sensor defective, Secondary air leak,

    Fuel evaporation control system defective, Air Flow Meter

    defective and/or the combustion is being disturbed by

    mechanical failure (Spark plugs,, compression,

    intake/exhaust valves, ...etc.)"
     
  28. jstar

    jstar Karting
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    Aug 8, 2014
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    up north
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    i had a 1121 1211 on both banks and surging issues. Cleaned maf with maf cleaner and all codes/ surging resolved!
     

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