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Thread: 7747 TBI Tuning: where to next?

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  1. #1
    Carb and Points!
    Join Date
    Feb 2016

    7747 TBI Tuning: where to next?

    Hey All,
    Before I start, truck is a 1990 4x4 GMC Jimmy with TBI, 350, 700r4, NP241, 33" tires, 4" lift.

    Current bin and logs are attached, using the $42-1227747-V5.9.3.xdf and $42-1227747-V5.2.adx

    Been working on tuning my stock TBI as a way to learn the ropes, in about a month I will be pouring about $5K into the motor and want to be up on tuning for it before I do. I have a good ALDL cable, an Ostrich 2.0, and a MiniPRO EEPROM writer.

    My motor is stock, worn out, the only things I have done are the normal tune up steps(new plugs, new wires, new dist cap, new air cleaner, regular oil changes) flip the lid on the air cleaner, and installed a AcDelco EP381 pump. Still running the stock regulator.

    So, right now I am running the ASDU base tune with VE tuning done(using the spreadsheet). Looking at my data logs I have a few questions on where to go from here.

    One: I was going to throw more timing at it but going by the knock counts I think the stock timing curve is about right, but curious on others thoughts(I.E. is the 200+ knock counts OK?)
    Two: The Injector Duty Cycle approaches 100% under WOT sometimes, so do I need to raise my fuel pressure to get more fuel going in, or am I reading too much into it?

    Overall the VE changes were minor, the biggest change I have done is enabling HiWay Lean Cruise Mode, which will pay for the Ostrich on its own with my improved MPG(I drive a LOT!)

    Thanks in advance!
    Attached Files Attached Files

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