Need Help/Opinions

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Irish_Eyes

Guest
Hey there! I just bought my car about four to five months ago, and things have been fantastic with it until recently. About two weeks ago, the check engine light came on almost simultaneously with the problem that when I was accelerating, mostly above 50mph, the engine would start shuddering rather violently. I went the day after that happened and got the codes for the check engine light, and all signs pointed to a bad spark plug causing one of the cylinders to misfire. OK, sparkplugs are no big deal, easy and cheap to replace yourself most times.

Yeah... most times. Turns out my car has three spark plugs, which in order to reach them, you have to do some extensive and near-dismantling of part of the engine. Well, there goes the idea of doing it myself. Took the car to precision tune, who've never steered me wrong before, and paid them 355 bucks for a tune-up, which also included an oil change(which I needed and usually runs me upwards of 50 bucks on its own).

Check engine light is gone, but the engine is still shuddering. Called my warranty service and they said I should try taking it to Hewitts. I called, but they couldn't get my car in for atleast two days. After talking to the mechanic, however, he said he thinks a coil(the one that feeds cylinders 2 and 3) might be going bad(the coil is of course not covered by warranty... bastards).

Here's my problem... is this a legitimate possibility? And is there anyone who could check this for me? Money is tight enough after blowing so much on the tuneup. It's certainly driving a lot better since the tuneup, the shuddering isn't as bad, but it's still there. I'd check the coil myself, except that I don't know what to look for or even how to replace it if that is the issue.

Any help would be greatly appreciated!
 
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Irish_Eyes

Guest
What vehicle?
Different coils on different cars.


Oops, sorry, thought I'd posted that. It's a 2004 Hyundai XG350, 6 cylinder, and the codes I got from when the check engine light were on reported that cylinder 2 was misfiring, which is why he suggested it might have been the coil.
 
Problem is, that a coil can appear to be working if you do a spark-gap test with an old plug, but it may not have the voltage required to fire that plug under the duress of acceleration. It's called "blowing out", like a candle. Yes, they do fail, but not terribly often. The only way to see if a coil is working properly is to use a spark/engine analyzer. Most home/hobbyest analyzers don't do a good job of it. You'd have to know the specific specs of the coil, resistance in ohms, firing voltage, etc... to begin to see if it's failing. An autopoarts place might have an analyzer that can do it.
 
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