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Q: Car sputters, shakes, and check engine light on

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My vehicle started sputtering and shaking on my way to work. After about 10 miles, I stopped at a store. When getting back in my car and starting it, the check engine light came on, flashing on/off. My car had almost no horsepower and I couldn’t get over forty (uphill, maybe 10). Most of the time the MPG gauge stays around 28.5 mpg, but it dropped to 19. I drove on to work and it was parked all that time. After work, I started it and it was running fine, but the check engine light was on continually. There was better horsepower than there had been that morning, but it was not normal. After 10 miles, it started getting sluggish - more and more. After pulling over, I turned off the car and let it sit for over an hour. After restarting, the engine light was still flashing and it started running like it did that morning. The more gas I’d give it, the worse the car would run. Can you give me direction on what is causing this and how to correct it?

Typically, when the Check Engine Light is illuminated and it is flashing, this is an indication that the vehicle’s engine is misfiring. This would also explain the symptoms on your 2007 Lincoln MKZ. If the engine has a misfire, then each time that cylinder fires it will cause the engine to run rough for a split second. The higher the RPMs go, the more times the misfiring cylinder is required to fire, and therefore the rough running engine happens the whole time because that cylinder may be misfiring several times per second.

I would recommend having a certified technician take a look at your ignition system to diagnose the shaking and sputtering problem. This inspection would cover the spark plugs, the ignition coils, and any wiring that may be associated with those two parts.

The most common causes of the issue you are having is faulty spark plugs and faulty ignition coils. If a spark plug is the cause of your misfire, it is recommended that all the spark plugs be replaced at once for best maintenance practices.

If an ignition coil is the cause of the problem, it is okay to just replace one because each spark plug has its own ignition coil on that engine and would not have any affect on the other cylinders.

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