How do you know for sure that coils are the problem?

[shstony831]

I have an 04 lincoln ls v6 and i wanted to know how I can be sure that the coils are the problem with my car.
My car tends to misfire at times. The steering wheel shakes when braking. It shifts hard when I put it in reverse at times. It also tends to struggle while accelerating at times. When accelerating, it will be at about 2 rpm when all of a sudden it goes to 3 or 4 rpm and jerks hard but then goes back to norma. I wanted to know if these were symptoms of coils being bad. I also used +87 gas for a couple of months since I didn't know my car used 91+ but been using it since then and I read that +87 gas could shorten the life of coils. Can anyone tell me that this is likely the coils? or should I go somewhere so they can be sure of it?

Also, who on ebay would be a good seller to buy coils from. I saw that alanisdeals is selling motorcraft for 160 so I thought about those coils. But i also saw some from per4mance_part$ on their. Who would be more reliable?I tried to include a link but for some reason my browser won't let me.
Thanks for any input

 

[Alax7]

The hard shifting when putting it in reverse is your tranny not your coils. Prob a selenoid going out.Send it to get it fixed if it's that bad or get a tune for it until you have time to take it in. Mine did it really bad but calmed down A LOT after a got a tune for it.

You can pull the codes from your ls if the CEL came on to get a better idea of the problem. You can just replace them, you can take them to ford/lincoln dealer or a place that can strees test them.If a coil is bad it causes the car to misfire, but a good coil with a bad plug will feel the same and bad injectors because they end with the end in the same place, the piston not working right. Most likely it's your coils. Most likely it's your coils but you shouldn't assume it's then for sure.

 

[joegr]

As was said, you have at least two problems.
1. The solenoid valve assembly in your transmission is failing.
2. You have an engine issue. It could be coils, plugs, something else (like the PCV), or all of the above. Getting the OBD-II codes read would be a good first step. Post the code numbers here. Don't listen to what the auto parts store says they mean.

 

[shstony831]

Well the check engine light has yet to turn on but it's been like this for a while. The PCV valve was just replaced by a Ford dealership in October when it had about 61,000 miles on it. It now has 69,000 miles on it or around that so I don't think it would be the pcv. It probably has nothing to do with the battery starting to fail since I replaced that a couple of months back.
I think it would be a plug or a coil but I can't tell and I probably can't afford to take it into a shop and have it all done in one trip since I'm a college student. Well I hope I can figure it out and maybe find a person around the Fresno area who can check it out and tell me.

 

[Sifrino3]

Now considering you have a coil on each cylinder. Lets say your having a miss on cylinder #4 for example. Switch the coil out from another cylinder. While you are doing the work. Disconnect the battery. Drive it around after words if the misfire switches to that cylinder. Theres your problem. Thats considering you have a mis-fire code.

 

[rainjacks]

You've got three problems, the shifting is an issue in the transmission. That might be solved by a computer flash. I seem to recall there being a TSB about it. The missing, hesitation could be Coils. Luckily you only have 6 that'll be cheaper than those of us with 8. Your third problem is likely a warped rotor causing the steering wheel to shake when you brake. You may be able to get away with having the rotor machined to smooth it out. More likely you need to purchase some front brake rotors.

 

[joegr]

You've got three problems, the shifting is an issue in the transmission. That might be solved by a computer flash. I seem to recall there being a TSB about it. The missing, hesitation could be Coils. Luckily you only have 6 that'll be cheaper than those of us with 8. Your third problem is likely a warped rotor causing the steering wheel to shake when you brake. You may be able to get away with having the rotor machined to smooth it out. More likely you need to purchase some front brake rotors.

My opinion on rotors for 90's+ cars is that you should never machine them. They are too thin when new. If you machine them they will just warp again soon. Replace them, they don't cost much more than machining would cost anyway. Make sure the lugs are not installed with an air wrench. Uneven pressure can cause some warp too. (It's okay to remove the lugs with an air wrench, but putting them on you should hand tighten. Bonus points for using a torque wrench.)

 

[rainjacks]

My opinion on rotors for 90's+ cars is that you should never machine them. They are too thin when new. If you machine them they will just warp again soon. Replace them, they don't cost much more than machining would cost anyway. Make sure the lugs are not installed with an air wrench. Uneven pressure can cause some warp too. (It's okay to remove the lugs with an air wrench, but putting them on you should hand tighten. Bonus points for using a torque wrench.)

Agreed on all points.

 

[bearsfan39]

I have the exact same problem for cylinder 5, replaced the coil pack and all new plugs, and still does it, so i order the rest of the coils to finish the tune up, so hopefully that will work and i still need to take a look at the shifting into reverse, you may get lucky and your tires may be low on pressure, i had that problem, put more air in them and its fine now