Yea, it's junk. From Popular Mechanics (
Looking For A Miracle: We Test Automotive 'Fuel Savers' - Popular Mechanics )
ENGINE IONIZER
The Electronic Engine Ionizer Fuel Saver consists of a couple of pieces of wire molded to some rubber blocks, which the manufacturer refers to as "capacitor blocks." There are no capacitors in them, however, as we found out during the test. The rubber blocks clip onto the spark plug wires near the plugs, and are intended to carry the "corona charge" from one cylinder's plug wire to the electrodes of the other plugs. This charge is supposed to "cause a partial breakdown in the larger hydrocarbon molecules in all the non-firing cylinders, resulting in increased combustion efficiency." Yeah. Normally, we try to prevent cross-coupling between spark plug wires to prevent crossfiring between cylinders. The Engine Ionizer seems calculated to promote crossfire.
THE DYNO SAYS: The truck we tested showed about a 15-hp loss with the Ionizer. About 10 miles into our economy test, the left bank of rubber capacitor blocks started to melt and sag onto the red-hot exhaust manifold. When smoke started to fill the dyno room, we interrupted the test and redressed the wires and capacitor blocks more securely. But when one on the right bank liquefied and dripped onto the manifold, we had flames a good 2 ft. tall, requiring the use of a 20-pound fire extinguisher. This, of course, terminated the test. Besides, most of the capacitor blocks looked like yesterday's chewing gum. Consequently, we have no comment as to the abilities of the Electronic Engine Ionizer Fuel Saver to reduce fuel consumption.