Fuel trims/AFR fluctuation

Discussion in 'Mazdaspeed 3/6 Fuel, NOS, Meth, & Water Injection' started by _russ_, Sep 23, 2021.

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  1. _russ_

    _russ_ Greenie N00B Member

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    Ive been trying to chase a fueling issue the past couple weeks, seemingly to no resolution. my longterm fuel trims are sitting at -20.44, give or take about 2% either way.

    I was watching my AFR otw to work this morning, and it dipped down into the 9.0/1 range, and i let off as soon as i saw that/felt no boost. Car has issues returning to idle after a quick rev up to 2.5/3k, as well as hesitates under throttle. I can try and grab some logs after work too, granted someone wants to take a look.

    so far i have
    -Had injectors cleaned+flow test, 3 of them were within factory flow spec, 1 was just a hair under.
    -new CS injector seals
    -Rebuilt my fuel pump, new o-rings/cleaned
    -replaced my pre-cat o2 sensor
    -replaced my MAF
    -replaced my coolant temp sensor
    -new ngk plugs
    -cleaned my TB and IM
    -Cleaned my MAP

    Engine wise the car is stock, factory intercooler, turbo, intake manifold. Has aftermarket CAI, but that is basically it.

    the lack of boost and the really rich afr as i get into higher load make me think a leak between the intake outlet on the turbo to the throttle body.
    Thoughts?
     
  2. jdab555

    jdab555 Greenie Member

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    When in doubt do a Boost Leak test, and physically / visually check your vacuum lines. I was chasing a gnarly issue with maxed out fuel trims, turns out I didn't fully seat the hose that runs from the PCV to the Intake Manifold when I did my OCC (only able to barely see it from under the car), and it popped off at an autocross.
     
  3. _russ_

    _russ_ Greenie N00B Member

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    Ill definitely check that tonight. I was going to replace my PCV valve tonight anyway since i just read on another thread that not evacuating fuel vapors from the crankcase can cause fuel trims to go pretty negative. Thanks for the reply :)
     
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