Squig

Someone please help me!!

I have an 08 tC manual with approx 130,000 miles
Mods(if you want to call them that): Throttle spacer and short air intake with K&N.

So recently when I come to a creep or complete stop then accelerate. The car loses power, sputters and shutters with the CEL flashing(less pickup than a model T ford). Eventually it will level out and power restores. This is intermittent and doesn't seem to have a specific pattern. Other than it only happens when I stop and accelerate. This used to happen every once and awhile and now it happens so much it is almost undriveable. Also the car has a rough idle that comes and goes as well. Reads that it's a misfire detected in cylinder 4 (P304 trouble code). There are several cause of problems for this code but I been striking out.

So here's what I've replaced and or switched around to rule out easy stuff like hoses under the hood, no vacuum leaks that I could identify BTW

*Replaced the PCV and cleaned the MAF(assuming a faulty MAF would cause all cylinders to misfire), no change.
*Replaced gas cap, no change.
*Swapped coils and fuel injectors around and still says cylinder 4 misfire though I've switched each of them to different cylinders.
*Replaced Cylinder 4 spark plug, no change.
*Replaced Vapor canister purge valve solenoid(under the hood attached to intake), no change.

So the only thing I can think of is the MAF but it only reads a cylinder 4 misfire and not all cylinders. So I'm inclined to think it's another issue that I'm unaware of. I've spent enough money on parts I didn't need so If someone could please help that would be awesome! I'm hoping that someone has the magic answer and I smack my forehead and say "why didn't I think of that".

Fingers crossed!

Louczar

You mentioned that you swapped coils. I just wanted to get a more clear understanding. You swapped the coil from cyl 4 with which other cyl?

If you replaced / swapped items from the last electronic part (spark plug) then lets look at this from a broader view.

spark plug - replaced
coil swapped with another cylinder
Injector swapped with another cylinder

Let me be sure to say I am not trying to be a smart a$$. Just trying to help you think it through.

I see 2 potential options from here.

1. have you checked the compression of that cylinder. If the problem happens more when the motor is warmed up then do it after it is so. Not a bad idea to check the others while you are at it. Not because I think there is a problem with the others, but why not check all 4 when you are it?

2. What does the coil pack plug into besides the spark plug? The coil pack wiring harness. Have you reseated all the connectors for the harness? I know you did for the 2 you swapped out. But did you for the main connector?

the last question is just because I am curious and nothing on you. I have done stuff like this before and anyone can make a mistake. Did you make sure you swapped the coil pack for cyl 4 and not have it backwards and swapped #1 cyl?

if you try these suggestions and it is still acting up, then what sends the signal to the coil pack wiring harness?

I hope this helps you figure out the problem.

take care,
Lou