[carman5575]

I have been working through a laundry list of issues on the 2003 Ford Focus Se 2.3L I bought my son a few weeks ago. Its nearing the end of the list now and my new headache is starting. I got to drive the car for the first time 2 days ago and it seemed like it had a misfire but it would do it when it felt like it...then I got it on the road and when I got up to about 50 it started doing it bad...if I let off the gas and pushed it again it seemed to help some. This car had sat for about 6 months with 1/4 tank of gas so I have my thoughts that the gas may be bad or condensation has put a lot of water in the tank. I had plugged my scanner into the car but no codes at all and the check engine only came on when I unplugged the coils to make sure they were working. The code that drew that was for unplugging the coils...Figured I would reach out to you guys who have been a huge help to me so far on this car.

 

[sailor]

Had an intermittent that was occasionally bad, found a setting on the scan tool that would give me misfire counts instead of having to wait for a pending code or "set" code.

Swapping the bad cyl. coil with another one, and having the problem follow the suspect coil, was the final answer (replaced bad coil).

Unless you get a J/Y one cheap, replacements are expensive. I waited until it goofed up consistently enough to test & found the bad one that way.

Hardly the only possibility, wanted to mention the swapping coil trick to tracing which messed up that you can do on these.

 

[freemind]

&^This x's 2

 

[carman5575]

Problem solved! After swapping coils around and not getting anywhere. I started to borrow coils from a friends car...long story short...I had to replace all 4 coils if i left any one of those coils in my car it would make all 4 cylinders misfire. I took a chance and bought a set of 4 brand new coils online for $35 with free shipping and it runs great now...funny how one coil would make all 4 cylinders misfire.

 

[Milton]

Well with a recently purchased, 12 year old car with an unknown maintenance history it's not that surprising to see all four bad. For all you know the prior owner sold his four good ones. Moving around a suspect part only works if the other parts are good.
Going through a laundry list on a new to you old car is the way to go. Make sure you do a visual inspection of all brake components, replacing the brake fluid is a must. Good luck!

 

[carman5575]

funny part is if I install 1 old coil with 3 of my new ones all 4 cylinders will misfire until I remove the 1 old coil. I had autozone scan it that way just for giggles and they told me I needed 4 coils for it and a new battery. Just goes to show just cause people have a scanner does not mean they are qualified to use it and diagnose problems with it.