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Thread: built 350TBI with 7747, rich across the board?

  1. #1
    Carb and Points!
    Join Date
    Feb 2013
    Posts
    4

    Question built 350TBI with 7747, rich across the board?

    92 k1500 auto, swapped in a 7747 ECM

    Newly rebuilt 350 TBI w/ TB mods like salad bowl & injector spacer, trickflow heads, bigger cam (not crazy tho, cam is efi compatible), flow matched rebuilt injectors, and more.

    I'm basing ECM off of the ASDU bin/PROM.
    Base timing at 0.
    Engine compression test, cold, ~170 psi.
    Vacuum test, solid 15 inches at idle w/ slight fluctuation.
    Fuel pressure at TB (with new fuel pump), solid 12.5 psi.
    New MAP sensor, cleaned EGR valve, new IAC.
    ACDelco R44LTS plugs.

    I have a wideband O2 and ALDL logger. Both are showing that i'm running way rich, pretty much across the board. Other than high RPM which is just a bit rich. During cold start/open loop I can smell fuel in the exhaust and I can see soot on the spark plugs. Its pretty bad. I don't get it, I should be pumping way more air through this engine. I don't want to lower the fuel pressure. What is the best way to lower fuel amount in the PROM?

  2. #2
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
    Posts
    6,285
    There is the option of removing 3% from the entire VE Table.

    There is also the option of using a VE Fixer spreadsheet from post 7 on this thread: http://www.gearhead-efi.com/Fuel-Inj...Information-42

    Addition information about the VE Fixer spreadsheet is on this thread: http://www.gearhead-efi.com/Fuel-Inj...r-Spread-Sheet

    dave w

  3. #3
    Carb and Points!
    Join Date
    Feb 2013
    Posts
    4
    Ok I found A problem, if not THE problem. My 02 sensor wasn't working right in the aftermarket exhaust headers. I went back to the stock ones and the mixture is quite a bit closer to being right now.

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