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Q: Cylinder #6 misfire on 4.0 liter SOHC

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I've replaced EGR plugs wires TPS idle control valve coil MAF sensor still show #6 misfire starts and runs but had vibration at 55 mph do u have an idea what this could be and has been wrong with similar vehicles cost to fix? Thanks Dan.

My car has 212000 miles.
My car has an automatic transmission.

A: Hello. Good job on getting the basic tune-u...

Hello. Good job on getting the basic tune-up work done! Given the mileage, this engine may have a longer-term issue, namely, accumulated wear on piston rings or a blown head gasket. Both of these can be diagnosed with a compression test, or a leak-down test if compression numbers are more consistent than engine running suggests. If the miss is constant and regular, a burned valve is also a good possibility. I recommend having a professional, such as one from YourMechanic, inspect the misfiring issue in person to diagnose this problem and assist with repairs.

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