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  1. #21
    LTx Guru


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    Join Date
    Apr 2013
    Vehicle
    1994 Formula
    Location
    Central NJ
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    1,799

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    At idle, the LTFT's are back to rational numbers 130 Left/126 Right. Seems like you have eliminated the vacuum leak.

    The problem I see is that the car has not been driven much, and the LTFT's in the seldom used fuel trim cells are still up at ~150-160. When you roll into the throttle in the 1,000-1,500 RPM range, the PCM moves to a cell that still has the ~160 LTFT's in it and the engine is suddenly running excessively rich. The PCM is gradually moving these 160 LTFT's down, but you haven't driven enough for all this to work itself out.

    Clear the LTFT's by pulling the PCM BAT fuse (under hood fuse box in 1995) for 30 seconds. Drive it over a wide range of throttle position/RPM so the LTFT's can fully develop. Then see if the hesitation is still there.

    It's not going to show up with the car sitting still and playing with the throttle, or with cold engine. The PCM doesn't use the cells that are causing the problem until it's in closed loop and the car is actually being driven under load.

    The hesitation seems to be a common lt1 issue but nothing really solid as a fix
    Totally disagree with that statement. There is nothing inherent to a properly running, properly tuned LT1 that makes it prone to hesitation in that RPM range.

    94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams solid roller / TH400+GearVendors OD / 4.11's/Strange 12-bolt / 300-shot (dry) N2O / Spohn Suspension / 6-pt roll bar /AutoMeter instrumentation / MoTeC M48 Pro engine management system /a few other odds 'n ends.

  2. #22
    LTX Member


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    Join Date
    Sep 2017
    Name
    Brian Rota
    Vehicle
    1995 firebird
    Posts
    28

    Default

    Thank so so much I will try this out, I do appreciate you taking the time to look it over. I have driven a little more since this report was taken so I will keep driving.


    =Injuneer;
    Totally disagree with that statement. There is nothing inherent to a properly running, properly tuned LT1 that makes it prone to hesitation in that RPM range.
    Well googling around hesitation at 1100 or 1200 came up

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