Check the spark plug and wire for Cylinder 4 first

If you see the spark plug is dirty, oilly, or damaged, change that. There is a list of things to do to pin point the problem, see if you can do the following:
1. Vaccum line: attach a vaccum guage to a vaccum line. When engine at idling, you should see a steady 16-20 inH2O (not sure about the level, check the repair manual). If you observe low vaccum level, or hear hessling sound, try to find out the leak and replace leaking parts.
2. Fuel pressure: Bleed off the fuel in the fuel line by remove the fuel pump fuse and cranking the engine. Then attach a fuel pressue guage and reconnect the fuse. Start the engine and then read the pressure. It should be somewhere between 40-80 PSI. Otherwise, you may have clogged fuel filter or damaged fuel pump, or fuel regulator. Follow repair manual to make the repair.
3. Fuel injector: If is is a multi injection system, it could be the fuel injector malfuction. It could be either the solenoid problem or the nozzle is clogged.
4.Ignition system: See the the coil has physical damage or corrosion. Then try to see the spark in a dark environment. If you can not see the spark, either coil, wire, or plug is bad. Replace the defect parts.
After repairing, clear the code and drive around.

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• Appreciate your response. -hiyou.- ♀ (61 bytes) () 12/01/2008 postreply 22:02:00