I’ve got a 2004 Chevy avalanche and O’Reillys
Say multiple miss firing is going on . I have
replaced the plugs & plug wires and still
misfiring & skiping can anybody help out ?
If you think a spark missfire, can you check for spark at the plugs, engine cranking or running. You might be able use a digital multimeter, lo voltage setting, engine running. Touch the meter lead to spark plug wire, one at a time. Note the reading. You don't take the plug wire loose and don't penetrate the wire insulation. It's an inductive reading. Some readings I've seen, .06--.07 volts. On some wires if reading bouncing off zero, that's where you start checking. Maybe a bad coil or wiring circuit to coil. If you suspect ignition coil, you can move it to different cylinder, see if problem follows the coil? Just about anything can cause a miss-fire, fuel--spark--compression?
Does it have coil packs? Checkem if so.