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I just got the spark plugs changed because my 2009 6 cyl. Jeep Wrangler (with 70,000 mi) was throwing code for a misfire. After the change, it doesn't run as smoothly as before. It chugs and skips, but does not stall. There are no warning codes showing up currently.

Is this considered normal for a vehicle with newly changed spark plugs? If so, how long should I expect it to take until it runs smoothly again?

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If you did them yourself check that the correct wire is going to the correct plug aka the firing order is correct. If you paid someone bring it back and complain. – mikes Apr 6 '13 at 20:51
Thank you for your advice. I'll be taking it back next week. – JohnZ Apr 6 '13 at 20:56
Hard to believe some mechanics are so unprofessional as to return a vehicle to you in that state (worse state than when you brought it in)... – R.. Apr 6 '13 at 21:32
up vote 1 down vote accepted

Your engine should run smoothly the second you change your spark plugs, smoother than before even, that's the whole point of replacing them. Otherwise, something else is wrong or was performed improperly.

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