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Q: What type of repair is needed when a third cylinder misfires? on 2002 Mazda 626

My engine light is on. After having it checked out I was told that the code says the third cylinder is misfiring. The mechanic then said the coil may be bad. After leaving, the car would not start and once I got a jump, it started jerking. What needs to be repaired when the third cylinder misfires?
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Code Description

P0303 Cylinder 3 Misfire Detected
P0303 Cylinder 3 Misfire DetectedPossible Causes Setting Conditions
Base engine mechanical problem that affects only Cylinder 3
Check for air leaks in the Air Induction system (e.g., in the intake manifold)
Fuel delivery component problem that affects only Cylinder 3 (i.e., a contaminated, dirty or sticking fuel injector)
Ignition system fault (Coil or Plug) that affects only Cylinder 3
Engine speed from 400-4,000 rpm; vehicle speed over 3 mph, and the PCM detected a Misfire condition in Cylinder 3 during the 200 or 1,000 revolution Misfire test under positive engine load conditions. If the misfire is severe, the MIL will flash on/off on1 trip!

This code sets in 2 Trip(s).
This code will turn on the MIL (Malfunction Indicator Lamp)

These are the parameters that set the check engine light for cylinder #3 misfire. Understand something, that one coil fires two cylinders. If one cylinder has a problem the other one will soon. A 4 cylinder engine doesn't run well on 2 cylinders. In fact, not at all!
Great answers above. Start with the plugs, wires, and injectors. Check all vacuum hoses for cracks, holes, etc. Also, if your vehicle has an EGR valve, check that to make sure gases can flow through it. Like Ron said, if it has alot of miles, get a compression test done, both wet and dry. Also a leak down test to check the valves. Good Luck!
It's possible the coil on #3 cylinder is bad. He will need to test the coil. He will also need to look at the spark plug(s), the plug wire(s) (if it has one on that cyliner). He also needs to know that the fuel injector that feeds that cylinder is working. One more thing, If the vehicle has 100k or more you should have the cylinder compression checked. All of these items can cause a cylinder mis-fire. I hope this helps!
Ron (AutoPros-Buford GA)
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