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355 355 96 5.2 check eng light

Discussion in '348/355' started by Beetle, Dec 12, 2020.

  1. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    I read the same info Ian did. Cat haven't done 1000k so far from ageing. My problem I believe and correct me if I'm wrong is that I have a possible injector fault and cheap **** downstream post cat sensors
    ( Lesson learnt). The only trim that is not functioning with the 10% working parameters is LTFRM1 Which has been 11.7/12.5% solid. That info comes from the scan tool. When I receive the sensors and install I will post any changes. If none injectors will be coming out but probably should be cleaned anyway.
     
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  3. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
    10,631
    San Carlos, CA
    Full Name:
    Mitchell Le
    First of all, you are all assuming that Ferrari does things like everybody else .... they don't.

    Beetle, I have seen this before, no more than a few months ago on a 355 5.2. The problem is not your cat converters or even your O2 sensors.

    Check the air leaks near the front O2 sensors. And check the condition of the knock sensors in the mess they call the V. Lastly, if the sum of the LTFT and STFT adds up to less than 10%, it's not a big problem.
     
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  4. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    John is it fair to say at this point that the post sensor LTFRM1 has an issue? IE slow to react possibly due to being a inferior item. LTFRM2 seems to be functioning correctly. Logic tells me that sensor 1 is where to start due to scan tool info? Hence the reason just replace both post cat sensors and see what the scan tool info reports.
     
  5. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    Knock sensors replaced at eng out service. It was a mess in there mate. I bought a smoke machine and intend checking the system Friday. What I can't get my head around is if it was an exhaust leak upstream then wouldn't the precat sensor be compensating? LTFRM1% 12.7??
     
  6. johnk...

    johnk... F1 Veteran
    Owner

    Jun 11, 2004
    8,637
    New England/FL
    LEV = Low Emissions Vehicles

    FTP = Federal Test Procedure

    DTC = Diagnostic Trouble Code

    Switchpoint = Voltage where ECU switched between rich and lean.

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    0.45 V = Point on the sensor voltage curve at stoichiometric AF ratio for a good O2 censor.

    I should not have said "zero shift". What I meant was a was a change or "drift" in the switch point. I was thinking of a zero reference. The swithcpoint (voltage at AF = 14.7:1) of an O2 sensor can change as it ages or become contaminated or damaged. In effect the sensor's calibration changes.
     
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  8. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
    8,637
    New England/FL
    Don't confuse fuel trim with sensor location. They are just bank 1 or bank 2. They are number derived from that the O2 sensors on each bank tell the ECU. I can not tell you what the problem is. All LTFT tell you is that the injectors are staying open 11.7% longer on bank 1 than the ECU was programed for because the O2 sensor is telling the ECU that with LTFT = 0% the bank was ruining lean. The simple truth is that, if the O2 sensor is good, then there is too much air in the exhaust on bank 1. Your code says slow response. That could be a number of things. Simple search:

    1. Check and repair exhaust leaks.
    2. Check wiring problems such as shorted or frayed wires.
    3. Check both the frequency and amplitude of the O2 sensor.
    4. Check for worsening or contaminated O2 sensor, replace if required.
    5. Check for inlet air leaks.
    6. Check the MAF (Mass Flow) sensor for the right operation.
    High LTFT could point to intake/exhaust leaks or MAF problem.

    Buy again, are you sure you don;t have the upstream and down stream sensors reversed?
     
  9. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    I'm going to swap post cat sensors bank 1 to bank 2 and so forth. This in itself will/should eliminate a bad sensor.
    I believe that the MAF would give high % reading on both LTFT due to being 5.2 version?
    All sensors are in correct positions.
    Smoke test will be done Fri. Thanks for your help John.
     
  10. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    Possibly found problem.
    Split brass compression ring/loose temp probe behind post cat sensor.
    Potentially sucking air into exhaust. Picked up on smoke test. No other leaks found.
     
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  11. Qavion

    Qavion F1 Veteran
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    Feb 20, 2015
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    Ian Riddell
    Was this on the right bank?
     
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  13. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    Yes mate LTFRM1. Im hoping that this is the issue just waiting on pack of Olives from RS Components. Couldn't get any metric olives locally.
    I'm also replacing both post cat sensors with Bosch brand
     
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  14. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    I don't know what this is? Have you resolved your issue?
     
  15. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    Yes resolved. Split compression olive was allowing air into the exhaust behind cats. Caused post cat sensor codes. The compression olive forms a tight seal around the thermocouple probe under the nut.
     
  16. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    ^^^^^Great to hear...congrats.
     
  17. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    Paul, can you post your fuel trim readings for both bank 1 and 2 now that you have resolved your issue. thanks
     
  18. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    Both LTFT'S are around .43/.46volts
    STFTs fluctuate but are no more than 6% +/-
    I erased the scan data after I seen they were .43/.46volt.(post cat)
     
  19. Targatime

    Targatime Karting
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    Feb 22, 2014
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    Could you post a link?
     
  20. taz355

    taz355 F1 Veteran
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    Feb 18, 2008
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    Grant
    Better yet put it in the parts sticky for 355s
     
  21. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    RS Components item No 293-6721 4mm brass compression olive
    Please note i had to file fit these to the thermocouple. 3/16' was to big.
     
  22. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    Is this a Ferrari part that is NLA? Is this something you added or is there a Ferrari part number for this?
    Can't find it in the parts manual
     
  23. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
    8,637
    New England/FL
    #45 johnk..., Feb 22, 2021
    Last edited: Feb 22, 2021
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  24. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    my question is whether Beetle has added these on his own? I don't have any compression fittings on my car, and I don't see them below?

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  25. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    Agreed. That's why I wanted Beetle to post his LTFT readings after the fittings were added; I don't think they would have changed, unless something else was done.
     
  26. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
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    New England/FL
    No, not added. Standard compression fitting on the TC mount to the cats. Come on the car from the factory.
     
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  27. Beetle

    Beetle Formula Junior
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    Apr 10, 2013
    776
    As previously stated one of mine was split. You only get the olive as part of the thermocouple kit from Ferrari.
    As per John's statement. I put this issue on here so people can check the area for leaks as mine was leaking in the area. On trying to tighten it would not stop leaking which required further investigation. New olive no more leaks no more codes.
     
  28. Carmellini

    Carmellini Formula Junior
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    Jul 16, 2019
    498
    Great to hear that solved your issue!
     

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