99 Ranger 4cyl 8 spark plugs

[Rabbi]

MY Ranger has developed a #3 misfire. I've changed the plugs, wires, but it is still there?? Help

 

[RonD]

Welcome to TRS

Gasoline engines need 3 things to fire
Spark, at the right time
Fuel, mixed with air
Compression, above 120psi

So a misfire means you are missing 1, 2 or all 3 of these things

Dual spark plug engines rarely get Spark misfires, both spark plugs would have to be bad, it can happen, i.e. 1 spark plug failed a year or two year ago, and now the other spark plug failed, so can happen just a long shot

So low compression or fuel injector issue is more likely
Compression is mechanical so good or bad, not intermittent, so usually best to test it and take it off the table or find out thats the issue so you don't waste time and money on non-fixes

Cold engine
Unplug BOTH coil packs, the 3 wire connector, pull both out, so no spark
Crank engine over a few times
Pull out either #3 spark plug, its tip should be WET with fuel, light the tip with a match/lighter, if it burns its fuel, lol
You can also pull out #1 or #2 plug to see if it has the same wetness
If spark plug is wet with fuel, injector is working, and you have changed the spark plugs, so that leaves compression, test all 4 cylinders, compare results

 

[Rabbi]

OK Thank you