I drive a 2003 Protege5, bone stock daily driver, 150,000 miles on the clock.

Recently it started stuttering occasionally especially while the engine was heating up. It finally threw a P0302 (misfire cylinder 2) code. I am not a mechanic but I decided replacing the ignition stuff on top of the engine would be easy enough. I found a youtube video which showed exactly how to do it so off I went.

I could only get 1 ignition coil from the auto parts place (all they had in stock) so I bought it, wire, plugs, and a PCV valve because the video I watched on Youtube recommended replacement of this as well while the other service was being performed.

I gapped all four plugs to 0.044 which I found online as the recommended gap, and installed them [the plugs I pulled out were gapped much wider, probably .060-.065] Not sure if this means anything? I also installed the new ignition coil and a new wire to off it to what I believe is the 3rd cylinder (the other middle cylinder that isn't #2). I reinstalled the second ignition coil and original wires as they had not been giving me problems yet.

I popped out the old PCV with no problem and installed the new one.

The engine seems to run well (no more stuttering or engine codes being thrown) but after it warms up, the idle is super low, like 150-200ish.

I am at a loss for what could cause this? There does not seem to be any hesitation when accelerating. No check engine light and I would say it runs fine as long as you are on the gas. Could this have something to do with the PCV I installed? The original was black plastic and the new one was translucent white although they are the same size/shape.

Any advice on troubleshooting and fixing this would be appreciated.

 

Update: I removed and reinstalled PCV valve and car seems to be operating normally. Not sure if it wasn't seated correctly before (or if that would even cause a low idle?).

Not a terribly fulfilling resolution but at least the car is up and running again.