Q: engine light-p303 cylinder 3 misfire, changed spark plugs,ingition coil and cylinder valves

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Hi,

Ive had a problem with my car for a couple months now.I had the engine light come on, done a diagnostics test,i got back p303 cylinder 3 misfire.I changed the spark plugs,ignition coils and got the cylinder valves professionally changed.The car engine light still comes on whilst I am driving and then the car starts to go in lag mode where it starts to run lumpy.I turn the car off and on again and the car runs fine.However,there is a constant misfire the car is producing.There are times when the engine light comes on flashing.I turn the car off an the engine flashing light goes and then there are other times,the engine light is static, i turn the car off and on and the engine light is still there.What could this be, any suggestions please?

My car has 55000 miles.
My car has a manual transmission.

Coils and plugs are usually the starting point for a misfire code, but some basic diagnostic work might save you some money. Sometimes I like to try swapping components from cylinder to cylinder to see if the misfire moves before buying expensive parts. There are a few other problems that could lead to a P0303, like ignition primary problems, vacuum leaks, or bad injectors, but those things are usually accompanied by other codes. It’s clear that you have a dead miss. When the ECU sees a consistent misfire, it shuts off the fuel to that cylinder to prevent damage to the catalyst. The the CEL will start blinking to warn you that you may be doing damage by continuing to drive. You’re at a point where you need to have a professional do some diagnostic work. by contacting Your Mechanic, you can have a technician come to your home or office to check out your misfiring VW and recommend a fix.

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