Changed the plugs on my son's 2002 Taurus today, this has the 3.0 Vulcan pushrod V6. The plugs removed were Bosch Platinum that I put in 80k miles ago. What was really strange is the three on the front bank looked really worn while the three from the rear bank were much less worn. Front bank had enormous gaps; about 75 to 80 thousandths while the rear still had the platinum tips and were at about 46 thousand. Why would the wear be different on each bank?
Strange Spark Plug Wear Pattern
- Thread starter Scout1
- Start date
Is it a waste spark system?
It is
That causes it. My jeep does it too. I assume it has something to do with the direction the spark jumps
Not sure the cause but do recall on some Fords, front and rear bank take different plug numbers. Maybe for this reason.
Go "double platinum tipped" to avoid the uneven wear. Can't afford/find them? ....go basic copper and change more often.
Interesting, I didn't know waste spark systems did that! Thanks for the info.
The car has 180k miles on it (with the original transmission no less!) so my son doesn't plan on keeping it so we just replaced these with some Autolite platinum's. Before we changed the plugs the symptoms were check engine light on with a multiple misfire code plus rough running on a warm start.
Maybe switch them around bank to bank after 40k? if it's easy enough to do...
My Ranger did the same thing with iridium's (waste spark). Went back to double platinum's and fixed the issue. Wasted good money (expensive) on iridium's.
The polarity change in wasted spark will mean that one plug will spark optimally from the centre electrode to the ground strap and the other plug will spark sub optimally from the ground strap to the centre electrode, That will mean different wear patterns with one wearing the centre electrode and one wearing the ground strap.
It's the 'polarity change" which baffles me.
Caveman Kira (me) sees the coil pack and spark plug wires and grasps any sparky-poo grounding to the head and block and through to the frame and to the battery's negative to complete the circuit.
Where's the path for current to the head to the plugs' grounding prong so it can spark to the center electrode...to where? ...back to the coil through the secondary wire? Maka no sense (graphically, anyway)
Caveman Kira (me) sees the coil pack and spark plug wires and grasps any sparky-poo grounding to the head and block and through to the frame and to the battery's negative to complete the circuit.
Where's the path for current to the head to the plugs' grounding prong so it can spark to the center electrode...to where? ...back to the coil through the secondary wire? Maka no sense (graphically, anyway)
The Ford Taurus SHO came out with this in the early 80's. From the factory the rear bank, the one that had spark from ground to center electrode came with double platinum and the front bank with the regular spark direction had single plats, ground strap only.
Yep. One of the spark plug leads is positive and one is negative. The block is ground, and it also has 2 voltages flowing through it (12v and 12,000v)
I don't know why this works but it does.
The dual output coil in a wasted spark system has the secondary flowing in a loop through one spark plug in the right direction and then back through the other plug in the wrong direction and back to the other side of the secondary coil.
Spark plug polarity can be an issue with points ignition where you want all the spark energy you can get but it's a none issue with electronic ignitions that have spark energy to spare. That doesn't stop points systems working in a wasted spark arrangement but it's less than optimum.
Spark plug polarity can be an issue with points ignition where you want all the spark energy you can get but it's a none issue with electronic ignitions that have spark energy to spare. That doesn't stop points systems working in a wasted spark arrangement but it's less than optimum.
