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update on 87 tbi K5 low rpm/ under load balking...

Discussion in 'The Garage' started by wolfy87, Feb 4, 2004.

  1. wolfy87

    wolfy87 Registered Member

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    Checked all the plugs, wires, cap, and rotor last night. 7 plugs looked pretty good, maybe a bit too hot burning (CR43TS). However, the #8 plug is getting oil/ fuel fouled even after replacing and testing. /forums/images/graemlins/doah.gif Truck seems to iron out and run on all 8 strongly when I get the revs up and pulling. Still have the low rpm, under load stumbling/ missing though.

    Moving on to checking the timing and then compression on #8 cylinder tonight. /forums/images/graemlins/thinking.gif With those symptoms, would that suggest overly advanced or retarded timing following that hypothesis? or am I just retarded? /forums/images/graemlins/grin.gif

    /forums/images/graemlins/1zhelp.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Idle and off-idle stumble is a dead giveaway for a vacuum leak a lot of times.

    I tweaked the engine/carb/distributor in a car I had for two years, never could get rid of the poor idle and "asg" when I tried to accelerate from a stop. Problem disappeared at higher vehicle speeds of course.

    Finally pulled the motor for another reason, found out I had hooked up a manifold vacuum port up to something that "leaked". Two years of bad driveability because of a hose I originally hooked up wrong. /forums/images/graemlins/tongue.gif

    Obviously in an '87 hooking vacuum lines up to the wrong spot isn't as likely to be an issue, but vacuum leaks from other causes would be just as likely.

    Don't know if you've already checked for these, but thats something to look at if not. A scan of the MAP sensor readings should show a vacuum leak if one were present I'd think.
     

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