Contour Enthusiasts Group Archives Forums General Troubleshooting spark plugs

Anyone have problems using bosch +2 spark plugs in 2.0 (1998) engine? I replaced mine with bosch plugs and engine started missing and check engine light came on.Replaced plugs with original plugs and cleared cel and engine ran fine. Removed plugs and compared bosch and motorcraft and found that the threads are not tapered the same. Went to parts store and compared autolight to motorcraft and autolights have the same thread pattern as the bosch. Replaced plugs with new motorcraft plugs and engine run great.

I'm not sure what you are describing about the threads. Autolite makes Motorcraft plugs. There is more than one configuration of threaded end that will work fine in that engine.

I suspect that it was the dual tip plug or just plain Bosch plug that made the difference. Bosch+4 doesn't work well in our engines either.

The engine really runs best with dual platinum plugs. Your ignition system fires two plugs in the conventional manner, center wire to side wire, and two plugs with reverse polarity, side wire to center wire. Messing around with the side wire configuration often is troublesome on coil pack "waste fire" ignition systems.