Alright. I've had a bad coil or two before. Maybe two years back. Replaced them all along with the plugs. But anyway here's my problem. I have a 2002 5.4 f150 4x4. Started out with my truck (every once in a while) having a rough startup. Taking a little longer to hold the key. But still always started right up. It idles fine and everything. But once I ease on the gas it sputters. Like it's misfiring. So I took it to advanced auto and put it on the scanner and he said no misfires at all and there were no codes in which could be the problem. He said something about an emissions code came up but was a confirmed code (w.e that means). Anybody had a problem like this? Could it still be the coils or spark plugs even tho no codes of misfiring cylinders? Just trying to pinpoint anything that could be the problem. Fuel filter? Pump? Any help would be amazing. Thanks guys!

 

I would think with an emissions code it's either cat related or your o2 sensors are going bad.

 

Replace ur iac

 

Don't you usually have a rough idle when that's bad/going bad? He said it idle fine.

 

Yeah my idle is fine. Just does that click noise when I'm sittin in the drive-thru but that's normal I believe. If not I'll figure that out another day. Just need to get this annoying sputter first

 

I have a 2001 5.4 and I have had trouble with a coil went bad and it idled fine but when accelerating going down the road it would run rough( shimmy and shake). Also seemed very noticeable when going up an incline almost thought I had tranny trouble until code came on. Don't remember the exact code off the top of my head but my #7 coil was cracked. I also had a bad iac(idle air control) the symptoms with my truck were when going down the road and would brake and stop at stop light motor wouldn't idle down I unplugged iac and it quit so then I replaced iac and it fixed that problem. I also had a vacuum leak one time but had rough idle. Hope this helps

 

Yeah my buddy had a bad coil before and it didn't show codes. So I'm hoping that's it. Only thing is if rather not replace all of them, basically because of time. I don't have much time on my hands but also wanna fix it myself. If anybody knows any other ways to somehow test, or narrow down to which coil needs replaced, it would be greatly appreciated

 

best thing to do is wait for a code to come up but ya can move coils around to try and pinpoint the bad one, think ya can also unplug em 1 at a time until the misfiring stops to find the bad 1 to, otherwise if you have access to a heat gun use that after the engine has been running for a bit to find the cooler cylinder which will have the bad coil, theres also a test ya can do at night where ya try and visually spot the bad coil but forget how that works hopefully someone who remembers it will explain