Rich at idle and lean at high loads after rebuild

Discussion in 'Mazdaspeed 6 Troubleshooting' started by Altenius, Feb 14, 2021.

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  1. Altenius

    Altenius Greenie Member

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    Hello everyone, I need advice on how to troubleshoot a problem with fuel trims. At idle, the fuel trim drops to nearly -20. Under light load, it increase to around +/-5%. As load increases, however, the fuel trims increase to 20+. Mods are autotech internals, catless downpipe, and JBR Tru-3.0 Intake, and a base tune. The problem persists with the stock intake as well. Engine also makes a rattling noise around 2500-3000 RPM.

    Any kind of advice would be great.
     
  2. jsmith

    jsmith Silver Member

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    Hold up. Base tune. What exactly do you mean by that? Who made it?

    You are switching intakes with same tune?

    edit: And then I read the user name. So maybe you know things. :)
     
  3. Altenius

    Altenius Greenie Member

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    It's the base high flow down pipe tune from VersaTune. The MAF is calibrated for the correct intake :).

    Also, I know much more about software development and reverse engineering than I do about engines, unfortunately.
     
  4. Altenius

    Altenius Greenie Member

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    Also - the injectors have never been serviced.
     
  5. jsmith

    jsmith Silver Member

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    Does Versatune have two values for fuel trims? Long term fuel trims (LTFT), or short term (STFT)?

    If so, which are you referring to with the -20 / +20 trims?

    You have a gen one, right?
     
  6. Altenius

    Altenius Greenie Member

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    I’m referring to LTFT + STFT. It’s a gen one.

    A valve was burnt before the rebuild so it’s possible this was a problem before.
     
    Altenius, via an iPhone, Feb 14, 2021
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  7. Altenius

    Altenius Greenie Member

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    Here’s the rattle noise. Sounds disgusting
     

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    Altenius, via an iPhone, Feb 14, 2021
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