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Thread: Stumble on Acceleration with very lean readings from wideband

  1. #1
    Electronic Ignition!
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    Post Stumble on Acceleration with very lean readings from wideband

    Hey everyone to start off here is what has been done to my 1989 Chevy S-10 4.3 liter Vin Z Computer #1228062.
    *All cylinders bored 30 over
    *New Pistons (do not have in front of exact ones)
    *Comp Cams Cam,Springs,Hydraulic lifters and Roller Rocker arms Part # 09-420-8
    -Camshaft C43 270H-R10
    *96 and up Vortec Heads
    *2114 Edlebrock Performer Intake manifold
    *Stiffer spring in TBI Regulator that pushes pressure from 13 to 18.

    The Prom I have in the computer now is the stock prom with Main Spark table changes to more of a vortec type table and EGR dissabled. The problem that I am having is that when I fire her up she runs good at idle nice and smooth. I throw here in to drive and head out and for the most part runs fine no problems until I try to accelerate with the pedal more than half way down to WOT my truck stumbles and hesitates but then if I just give the pedal a little push it gets going accelerating normally. My wideband 02 sensor shows a really lean mixture during the stumble like somewhere around 22.3. I have attached my latest data log its not way long but shows the problem. Thank you for the advice and opinions in advance im pretty much at a loss at this point.reference.
    Last edited by S10Sanity; 01-26-2015 at 01:58 PM.

  2. #2
    Fuel Injected! brian617's Avatar
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    Try adding more TPS AE in at 20% at a time.
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  3. #3
    Fuel Injected!
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    Quote Originally Posted by brian617 View Post
    Try adding more TPS AE in at 20% at a time.
    ^^ Except know you have Vortec heads and a large carb style plenum I would do both TPS and MAP AE values. I would multiply all but the lowest values in both tables by 1.5. I leave the lowest values alone because it seems to do weird things to the idle/off-idle tip-in if you

  4. #4
    Electronic Ignition!
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    Thanks for the replies guys I have been out of town for the past week so now I get to play around with this stuff. Thanks again.

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