Check Engine Light / Engine mis-firing

[110reef]

I posted this in the vert forum, since that is where I spend most my time, but I figured there were a lot more people over here that might help.

I drive my car every day, never have had any problem with the motor so far. Got in it Friday and when it started up, I noticed it was running a little rough. No worries, just thought it might need to warm up a little. As I am driving out of my neighborhood, I notice far less power than normal and it is still running rough. Go a little further and I notice the check-engine light is on. I stopped and turned off the motor and re-started, no improvement. So I took it back home and got the other car and came to work.

Took it to Autozone and they read the code. It said #4 cylinder misfire. So I pulled the coil and spark plug to see if I saw anything obvious, but I didn't see anything visually out of the ordinary. So I figure it is either the coil not working or the fuel injector not working on that particular cylinder. Especially since it happened suddenly, I am thinking it is an electrical related issue.

Any tips on how to troubleshoot this?

By the way, just priced the parts if it is the coil or the injector. A coil is $95.06 and an injector is $116.40. That is for 1 cylinder! Plugs were something like $25 each! Boy this BMW stuff is expensive! A whole set of plugs for my Ford is <$25...(That is without labor, since i am free! ) So, correctly troubleshooting this would helpful so as not to spend a fortune.

[m2pc]

This happened to me before and it ended up being a bad coil.
Swap the #4 and #1 coilpacks, reset the code and wait to see if you get another CEL illumination.

If the problem "follows" the coil to #1, then it's either the coilpack or the rubber boot itself.
At that point, try swapping on a new boot and see if the problem goes away.
It's cheaper than replacing the coil, and chances are you could use a new set of boots anyway if it's unknown when they were last replaced.

As for pricing, I suggest you shop around. Avoid the "stealership" or other high-priced vendors at all costs.

These are popular:
http://www.pelicanparts.com/
http://www.bimmerworld.com/
http://www.mesaperformance.com/ <- My favorite local shop where I get almost all my parts.

[travis325i]

i had this problem also when i bought my car it would misfire above 4,300 rpm and then a couple winters ago another coil died and i was runnin on 4 cylinders i ordered aftermarket coils from www.bavauto.com they fixed it and they are really priced well so if your looking for a good upgraded ignition you can get them there. i love mine you get all 6 for like 280.00 thats way better than the price of 6 oem coils

[110reef]

Thanks for the suggestions. I will give it a try, switching the coil to another position. Hopefully that is it, the fix is easy enough. Looks like a set of 6 (the higher performance ones) at Bavauto for my car runs $405 on sale. The regular ones will be $329.70 plus the $41.70 for the connector boot = $371.40. I may just go with a single one since I didn't have any problems before.

I'll let you know what I find out. Probably won't work on it til Friday.

[110reef]

Ordered a new set of coils, boots and plugs today. Sure hope this solves my problems! (All for about $150 including shipping from fcpgroton)

Will let you know how it turns out.

[110reef]

Installed new plugs and coils this weekend, car runs smooth, check engine light gone. All is good again!

Thanks to those who helped me troubleshoot this and told me where to get great prices on parts!