So I recently changed my oil which i'm pretty sure has nothing to do with this, but once i started the engine after the oil change it was running terrible and and the check engine light came on. The truck seems to only be running on 5 cylinders, it pings when i accelerate, and you can smell the unburnt gas from the exhaust. i have replaced the coil, spark plugs, and wires with no success. I have checked the compression, the plugs for spark even though all those components are new, and i swapped the injectors from cylinder 1 and 2. But still cylinder one is still misfiring and I cannot figure out why.

Can anyone give me any suggestions? is this possibly a pcm problem?

 

Yes.

1) It's always a good idea to give the year, make, model and other pertinent facts when asking technical questions. Without those, no one can give any vehicle specific info.

2) If this problem started immediately after work was done under the hood, then there's a very high probability that it is related to that work. Look around for disconnected or damaged electrical connectors or wiring, disconnected or damaged hoses.

3) The CEL is there to help with diagnosis. Finding out the trouble code(s) will point you toward the problem.

4) It is extremely unlikely that the PCM could cause a single cylinder misfire.

 

Hate to tell you this, but I have a 05' ranger edge, 3.0 v-6 and I had misfire codes . I replaced everything to do with ignition and nothing helped. Then I read about a common problem with the valve seats in the heads were recessing and causing low compression and misfires. I replaced both heads, yes both! The problem went away!! Awesome, no more stupid little engine light between the tach and speedo. Just to make that go away was worth it.

 

This post needs to made a sticky.

 

It's a shame you didn't investigate you problem first instead of throwing parts at it.For anyone reading this now, a simple process of elimination will lead you toward your problem. an engine needs three things to run, Compression, air/fuel mixture and ignition. Start with the simple things first.

 

nope, def not a pcm problem. The pcm will not cause a missfire on one cyl. Honestly it sounds to me like you have and air/fuel mixture problem, possibly MAF sensor.

 

My 2005 stx started misfiring going up steep hills, then it started missing at idle. I tried a new fuel filter then the check engine light came on ( po301 ) so i pulled # 1 plug and it looked fine. I ordered a ( new ) coil pack for $23 from eBay. The coil pack fixed it, i drove it home from work where I replaced the coil pack ( 20 miles ) at 90 mph and it ran great. I would have diagnosed it sooner the code never came up until check engine light came on.

 

I have a 99 ford ranger 3.0 flex fuel. I just rebuilt the engine and have literally replaced everything that has to do with the ignition, fuel, or drive train and I'm throwing drive not complete code misfire cylinder 1 then a multiple misfire code... all I can think is the injectors seeing how everything else checked out fine.. what do you think?

 

did you replace the ignition wires as well

 

I have done the process of elimination, it has cost me a bundle. Unfortunately my problem still persist however not only does the engine light come on but it starts to Blink and then my truck sputters like it's not getting enough fuel. I replaced the coil pack spark plugs spark plug wires the Overflow sensor both O2 sensors the throttle body gasket the upper intake gasket and now I'm replacing the fuel injectors. I hope to figure this out soon because if I have to replace the heads I am going to be pissed. Ford out did itself with screwing the public consumer on this one and after this I highly doubt I will buy another ford. .. other than that thank you for your advice

 

well you know I’ve also had condition like this and the first time ended up being a clogged cat. While it’s running have someone rev it up couple times to about 2000rpms quickly and feel how much air is coming out the tailpipe. If it’s not much then your cat is clogged. Also I’ve had an instance where it was the purge valve. Oh and possibly check fuel pressure regulator.