Well, found another issue... corroded/messed up plug wires... when I replaced the plugs, I messed up one wire (the metal thing pulled off). I just replaced all the plug wires, and at least one other was all jacked up too. These were Bosch premium wires, less than a year old, and properly installed at the time.

I have nothing but issues with Bosch electrics, be they on a Volvo or a Porsche... Is Bosch a subsidiary of Lucas, or what? LOL.

I like the Bosch copper-core, metal-endcap spark plug wires over Bougicord.

I think it was on this board where I read someone say that Bosch as a brand is not the problem, but you might want to look for the country of origin on the packaging.

In one or two accounts where someone was dissatisfied with Bosch plugs, and they identified the country of origin, it was China or India. This is just hearsay from my fading memories, and may not have come from a reliable source in the first place, so I pass it along just as a rumor that merits some data collection, not a statement of a known problem.

I use Denso and NGK, but it would be helpful if Bosch users would make note of the country of origin and report back if they detect a pattern.

I think I agree with Randy: I've put only Bosch Platinum plugs in my 1991 745Turbo (Bosch LH 2.4 fuel injection system, Bosch EZ-116K ignition system), which has a normal, cylindrical coil made by Bosch, and a distrubutor mounted on the rear of the cylinder head. Seems like I've never had any trouble with them.

May try copper plugs next year. But, in the mean time, at least on the cars with the more advanced EZ-116K ignition system, the platinum plugs seem to be okay.

By the way, you have to identify your ignition system by looking at what is actually in the car. Don't go by what some list in a manual says: Even Volvo's manual lists the EZ-117K for my car, but it clearly has the more advanced EZ-116K in it, as shown by Volvo's own chart of which components indicate which system.
--
Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)

I have used a lot of different sparkplugs including Bosch Platinum and I have never had a problem with them. They seem to take more than their fair share of abuse.

On the other hand I once was involved with looking into a no start situation that was solved by installing new sparkplugs (the old plugs were plain jane Bosch) This is no reflection on the reliability of Bosch plugs in general- they just had run their course.

Randy