Contour Enthusiasts Group Archives Forums Modifications Duratec Performance What is the best spark plug to use on SVT's????

I was using the motorcraft plugs, the ones that came with the car which had maybe 20K miles on them when I had all that stuttering in my car early this year. After changing coil packs and new wires it was mostly gone. Anyway, I occasionally got a low rpm stutter/misfire from them so I decided to change the plugs back to the bosh platinum +4's I had used earlier. I had tried the +4's as a test when I had an unmodded 2.5L in the car and didn't find any benefit to them. I warrantied the plugs with Autozone (my buddy is a manager) and changed out the now 20K motorcraft plugs back to the new Bosh +4's. Idle was better and no more midrange stutters. THat has been 7 months and still good.
I learned the ford ignition system inside and out while developing that add-on module for the emanage and I can say that the plugs wires and coils are each equally important to the igniters in the pcm. The trouble is, you need an oscilloscope to see the kind of noise that is being introduced into the coil primaries and by using different plugs and wires.
My advice is to use the factory plugs (posted earlier) so that it gets as close to the orignial impedance on the igniter circuit as it was designed for.
I have put many hours with an o-scope into this ignition sytem and let me tell you that the less noise the system experiences the cleaner the individual sparks will be and the better your car will perform all through the rpm range.

warmonger