cel P0304

1999 Tiburon, 2.0 DOHC

Suddenly - out of the blue, began to run rough. Got a CEL P0304 code extracted from reader. #4 cylinder misfire...

I pulled #4 wire and checked spark - very much appears strong and consistent.

I do hear what could be a vacuum leak through what appears to be a small electric vacuum pump behind intake. It has a half-inch hose intake from main air intake (opposite MAF sensor), runs along firewall to a small air pump(??) and then into intake.

The car simply will not run if this pump (??) is disconnected. On key positition "ignition on", the little pump starts up. On starting the car, I begin to hear a possible vacuum leak "hiss sound".

I cannot see or feal any other source of vacuum leak.

Am I barking up the wrong tree - is this simply an injector problem? Or may it be as simple as a vacuum leak (affecting the fire of cyl #4 only?)

Thanks for any help...

bring it into dealer... you should still have a warranty on it.

bring it to the dealer. Even though you get good spark coming out the wire the wires on these cars tend to get small holes in the side of them the spark then taes the easy way out and goes into the head instead of through the sparkplug .