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  •  » Engine running rich?

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    4/02/2020 4:07 PM  #1

    TremendousWand
    I FYI 24-7

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    Registered: 5/16/2013
    Posts: 657

    Engine running rich?

    1966 mustang, 1988 5.0 HO SWAP, MAF, EFI

    I drove my car to the exhaust shop today and it started stalling literally as I was pulling in.  I'd drove it around the block a few times earlier in the week w/ no problems to make sure it was good enough to take on the road.  
    The car only has shorty's installed as of now.  No O2 sensors connected.  The ECM is from a 1990 Mustang 5.0.

    While I was at idle the car died and started giving out some black smoke from the headers and stalling.  The fuel pressure is holding.  It seems to be fine at higher rpms and on the road.  Will the air fuel mixture be corrected once the Exhaust system is installed and the O2 sensors are connected?  With no O2 sensors, how does the air fuel mixture get calculated in a MAF setup? 

    Thanks.

     

    4/02/2020 4:31 PM  #2

    Bullet Bob
    Senior 24-7 FYI Addict

    Online!

    From: Montrose, Colorado
    Registered: 4/01/2013
    Posts: 4,888

    Re: Engine running rich?

    Probably trying to go into closed loop with no HEGOs.  What other mods have been done to the engine?  What codes is it reporting  besides the open HEGO ckts?  It may have ran around the block but never got warmed up to go into closed loop.
    I'd say get the the HEGOs installed and connected, then disconnect the battery for a half hour or so to reset any codes, then run a KOEO test to make sure the ECM is happy with what it sees, then see how it runs.

    BB1

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    4/02/2020 5:23 PM  #3

    50vert
    Senior 24-7 FYI Addict

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    From: QLD Australia
    Registered: 4/01/2013
    Posts: 1,427

    Re: Engine running rich?

    ^^^ what BB1 said.
    In open loop, fuel is calculated with no input from hegos.

    Last edited by 50vert (4/02/2020 5:24 PM)

    "Those telephone poles were like a picket fence"
     

     

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