Problems with fuel trims

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Mazda3speedster, Aug 19, 2021.

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  1. Mazda3speedster

    Mazda3speedster Greenie Member

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    so my 07 speed 3 has a boost leak making only 13 psi, it usually makes like 19-20, and the fuel trims were very negative LTFT would sit at -20, and STFT would go +-25, I found that my turbo inlet has slipped off a bit so I put it back on. On startup, the trims were not perfect but they were better After a short amount of driving I noticed that I accidentally forgot to plug in the vacuum line for the blowoff, so I went to plug it back in, this made the fuel trims go even worse than before(LTFT +-15, STFT+-25), wondering if I have a bad blowoff and how I could test this. Also have a log of all this I can post, not sure if that help diagnosing my issue
     
  2. StayFrausty

    StayFrausty Frok Greenie Member

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    Easiest way to most likely fix this issue is build yourself a boost leak tester and test from the intake.

    Implementing smoke is going to make things very easy but I use a 40 dollar harbor freight pancake compressor and built a 3.5in (intake size) plug with things from Home Depot/Lowes and run 30ish psi to it and am able to listen for most leaks and then feel around. There’s videos online, pretty cheap and easy, and an extremely valuable tool to have with boosted cars.
     
    StayFrausty, via an iPhone, Aug 19, 2021
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  3. Awafrican

    Awafrican Moderator Gold Member

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    boost leak test needed



     
  4. Mazda3speedster

    Mazda3speedster Greenie Member

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    Ok Ill try those out hopefully nothings to broken
     
  5. Mazda3speedster

    Mazda3speedster Greenie Member

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    So I did those tests didn't find any boost leaks but I just took apart all the hoses afterwards and tightened everything and it seemed like one of the hoses to the EBCS was loose so I took it off and put it back on (it wasn't actually loose in the first place it just looked like it), after this I was back up to stock boost when I went to the store, on the way back I was back to making 13 psi max. Also when I was driving on the way back the car seemed to drive weird dash was flashing and DTC and ABS lights were on I just put it in neutral till it stopped. Not sure what the problem could be
     
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