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Trying to tune-up a Vortec 4.3 engine, GMC Jimmy 1995 V-6

Discussion in 'General Chevy & GM Tech Questions' started by bunfish, May 22, 2011.

  1. bunfish

    bunfish New Member

    I can't believe what a nightmare it is to tune-up my car. I've changed the plugs, wires, distributer and rotor, and still it's misfiring. What else do I need to do in this incredibly awkward and difficult truck? I hate my engine.:grrrrrr:
  2. texas99lb

    texas99lb Rockstar

    Hey bud, first off calm down...Dont hate your engine, Did you make sure you distributor rotor was in the right position when installing it. Also check your plug wire configuration, make sure you firing order is correct. Did you change your air and fuel filters as well?. Are you spark plugs gapped correctly? There is plenty of things that will make a truck misfire, if that truck running like absolute crap or is it just a miss or hesitation. You timing might need to be looked at as well. You can take it to a shop and have them check your timing with a timing gun to make sure it is correct. Hope this helps a bit..Remember, love your truck, because it carts your ass around. Good luck..
  3. Crispyt

    Crispyt Rockstar 100 Posts

    I have the exact same engine in my 1995 C1500. Mine has always had a small skip at idle and no matter what I have done it never has fixed it. But, the 4.3L is known to run a little bit rough because of its odd crank throw as it is almost a full crank from the 350. Same block and everything only the back 2 cylinders are removed from the block. This has made the 4.3 a weird engine. They fixed the rough idle issuse and installed a balence shaft on the newer models. How bad of a skip is it? Is it only a small amount? Only at idle? Make sure the dist. is set and timed right, and like texas said check everything simple. Also try cleaning your EGR valve in the back of the throttle body. I did that on mine when it was idling really bad and it helped it a lot. I used a brake cleaner and cleaned it really good. Make sure that you don't have a vacume leak or that your purge solenoid isnt stuck open or closed. Do you have a service engine light on after you drive it for awhile too? Also try replacing your Ignition coil. Its only about 40$ and those break down over time and cause misfires.
    Last edited: May 24, 2011
  4. Loyal Chevy fan

    Loyal Chevy fan New Member

    I had a '91 - 4.3 engine with over 225 ,000 miles on it , and it was still running great. If it stumbles off idle , I would look at the throttle position sensor first, In the Haynes repair manual it tells you how to check it.

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