1989 Chevy misfire help!
October 17th, 2015, 3:41 PM
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1989 Chevy misfire help!
89 Chevy 2500. 4sp 4wd. Got this truck out of the weeds. Only has 51,000 on a new motor. Previous owner parked it cause it was mis firing. I bought it to fix up. Here is what I found : plug wires bad. Cap , rotor, distributor corroded terrible. Intake gaskets vac leak. Tbi gaskets leaking. Here is what I have done : put new intake gaskets in. Rebuilt tbi (just gasket kit). Plugs, wires, cap, rotor, coil,dist pick-up coil new. Timing set at zero deg with wire unplugged. I stil have a slight misfire throughout the whole rpm range. Replaced the map and ect sensors. I know I shouldn't just throw parts at it but from experience, corrosion is baaaaad so That's why I replaced stuff. I think I'm having a spark issue tho. My comparison has been a 92 truck with the same stuff. I have one of them little spark pens that you lay on the spark plug wire and it lights up every time that plug fires. My father has my "comparison" truck. When I put my spark pen on his plug wires it lights up awesome on all plug wires. I take that pen to my truck I'm workin on and only bout 3 plugs have that good consistent spark like my dads does. The other plug wires when I put that pen on them, light up at random it appears. The coil is workin great. I took that spark pen to another vehicle thinking the pen is not working but I was wrong. It lights up and shows ya that plug firing every time as long as I'm touching that wire with the pen. So I don't think my pen is bad. I haven't replaced the ign module at the base of distributor yet. Comp is good across the board. Bottom line is that I've got good energy goin into the cap but coming back out to the plug wires seems lackin like it's not telling it to "fire now" . Any help is great!
October 25th, 2015, 8:24 PM
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have you replaced your pick up coil in the distributor,sounds like it maybe bad.i have come across this on the older gm engines.also check for play at the top of the distributor shaft,if there is any play in the bushing it could cause the reluctor wheel to touch the pick up coil in the distributor and cause a missfire.hope this helps.