My 2000 Sonata (V6) suddenly started misfiring and was displaying code P0303 "Cylinder 3 misfire detected" so I figured it was either the plugs or plug wires. I cleared the code and replaced the spark plugs with Bosch platinum plugs and nothing improved. It still was displaying the same P0303 code. Disconnecting the #3 plug wire did not worsen the problem so I surmised that the wire was bad. Since the car was under warranty, I took it to the dealer who replaced the spark plug wires, but insisted that the new Bosch plugs be replaced as they were contributing to the problem. They told me that Bosch plugs should never be used in a Hyundai as they caused misfiring. I called another dealer and they told me the same thing, that Bosch plugs were not to be used in a Hyundai as they would cause misfiring. I have contacted Bosch USA and several indendent mechanics and none of them have ever heard of this problem. Just wondering if any of you are aware of Bosch plugs causing this type of problem. There are four Hyundais in my family so I would really like to know if this is a real problem before I replace any more plugs. Anyone ever hear of Bosch plugs causing this type of problem? Thanks.

Jeff

 

I just bought a set of platinum 4's for my Accent I'll let you know if I have a problem.

 

bosch spark plugs are the worst plugs on the planet!!!!!!!!!!!they casue problems in any vehicle you use, gaurenteed! the reason, all the distributorless ignitions that use "coil packs", are whats called a waste-spark ignition. basically, on lets asy a four clyinder engine, clys 1-4 and 2-3 are paired together. when the spark is fired to clyinder 1, the spark occurs, travels thruogh the block, and BACKWARDS through #4 cly when its on its exhaust stoke, bask to the coil were ground is. its usually the reverse firing of the plugs that cause bosch "crapnums" to casue misses. if you look at the center electrode, its very tiny, compared to lets say a plain ac delco, so when i say they fire backwards, that means half the clyinders are firing from teh ground electrode to teh center electrode. makes bosch products horible. and besides, +4's are supposedly 4x's the platinum, WRONG.....all bosch plugs only have platinum at the center electrode, NOT teh ground electrode, were half teh plugs in the engine will wear out faster. my suggesting, just stick with factory plugs, or if you want, just get some autolite, champion or ac delco double platinum.