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2014 Buick Regal cylinder 4 misfire


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I own a 2014 Buick Regal 2.4L Turbocharged, automatic and has just reached 100k miles. I'm getting the P0304 code. Found out it was a misfire so I bought 4 new spark plugs and 2 ignition coils. One for back up. I changed out all my spark plugs since they needed changing, and changed my ignition coil for cylinder 3 and 4. My car is still shaking when I drive it and already had to replace number 4 ignition coil twice. I took it to the same mechanic that changed out my ignition coil. Today, they told me that the valve in one of my cylinders is bad.  Any advice? Thanks I enjoy your channel. 

This topic was modified 2 months ago by NotAMechanic94
3 Answers

How did they determine a valve is bad? Compression test? Leakdown test? Did they give you the actual  results of the tests? If you do have a bad valve in that cylinder then at a minimum you would need the cylinder head rebuilt or replaced and other repairs may be needed while in there.

Since this would be a major repair ($$$$) you might want to get a second opinion. Take the car to another local independent mechanic and don't tell them the previous diagnosis, see what they say is causing the misfire.


Bad valve sounds fishy to me.  Like @chucktobias said, a leak down test would confirm a bad valve but you definitely need a second opinion.  Have the mechanic follow these items to diagnose the cause of the misfire -

Sounds fishy to me too. Granted, it's a post-bankruptcy GM product and turbocharged, but as far as I've been able to find those are not particularly known for burning valves.


Scotty answered at 3:38