In this application they were going into a 4.0 L6 engine for a 2004 Jeep Grand Cherokee Laredo. The old original plugs, which were a different brand, were not even remotely gapped properly. When one of the plugs I removed was .100 I suspected that there might be an issue with why it was running poorly. You see, I bought this car used, and while it sounded good, it was burning a little rich and I could smell unburned gasoline.
The reason why I decided to change these plugs, was because I was doing a full tune up and repair on the vehicle which meant changing out the coil pack assembly, the sensors, timing chain, all of the emission and starting components. That said, Taking out the old plugs was the stuff of nightmares. Not so much the getting them out, it was what I found that disturbed me most. Not one of the original plugs was gapped correctly. In this application they are to be gapped at .040.
Autolite has made spark plugs for an extremely long time and I have had them in nearly ALL of the vehicles I have owned, including some motorcycles, and lawnmowers. They are simply the best plugs for the money you can buy.
What kind of vehicle do you drive? 2004 Jeep Grand Cherokee