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Thread: on boost hits fuel cut

  1. #1
    Cairnsy's Avatar

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    on boost hits fuel cut

    I had recently fitted a manual boost bleed valve and had the car runing sweet until i junod a tooth. Got it back and was runing fine until i fited and adaptor to make a round hks mushroom filter bolt to the airflow meter. Now the car sounds great when i let off but wen i nail it it starts to make boost n then al of a sudden hits fuel cut. It never done this before with the standard airbox on. Has any one ant ideas? I havnt fitted an uprated fuel pump yet before thats suggestd. But it was runing fine before fiting filter

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    Subaru ETA's Avatar

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    Its because of the crap filter.
    You will have to turn the boost down.
    If you search pod filters around here you will see that it has been proven that the standard air box with a decent panel filter is better
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    Nick Mann's Avatar

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    Agreed. The mushroom filter in front of the maf is messing up the airflow through the maf. Most after market filters that bolt direct to the maf cause that problem.

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    i agree with above.
    you will either have to put stock air box back on, or turn the boost down, or fit a length of pipe between the pod filter and the MAF, but there is not a lot of room to do the last one, or get the fuel cut limit raised and risk a bad Air Fuel Ratio and potentiall damage the engine due to the mushroom filter.

    Bye for Now!

  5. #5
    Confused's Avatar

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    The best option is to ditch the mushroom filter and put the stock airbox back on.

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    Brilliant thanks for the advice its geting ripped off whe i get home from work lol

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    mushroom filter are not bad things they just don't like being on a vr4 without the correct modification to the air intake.

    you can still sell it on to another type of car person paricularly if they have MAP (Mannifold Absolute Pressure) sensor in stead of MAF (Mass Air Flow) sensor. this is why you see mshroom filter directly on the front of turbos on some setups. i would assume they use MAP sensor.

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    Davezj u can also have positive pressure maf sensors aswell that go after turbos. But usually setup with map

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    Nick Mann's Avatar

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    There are different types of maf too. I think I remember someone saying that Karman vortex type are more susceptible to non-linear air flow.

  10. #10
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    very true, i have just stripped apart me spare MAF and it is quite a complex little device, the sensor is on the bottom of the black square box and the air pathways up through the middle of the vertical black bar to a type of refector up inside the tube near the sensor.
    interesting.
    It is no surprise, that if laminar air flow is not present across the cross section of the MAF it will upset the readings.

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    If you use the correct pod/maf adaptor it will work fine... But as the guys say above the mushroom ones are the wrong type.

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    Sorry thread revival. I hit fuel cut for the first time ever last night. 14.5 psi boost, about 5,000 rpm. It was super cold if that makes any difference. I have just added hard piping as well. Fuel pump is factory too

  13. #13
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    Cold does make a difference.
    The fuel pump has nothing to do with it, it is the car seeing a certain amount of air that triggers the fuel cut.

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