Rough idle power loss

[Somethingbigandorange]

Looking for some advice. Idling rough, losing power, check engine light flashing. Throwing P0300. Misfire count on cylinder two is ten times the others but all are showing some misfires. Fuel is 60psi even when sputtering. Plugs are clean and gapped correctly. Throttle body is clean. Air filter is clean. No fuel smell or smoke out of the exhaust.

When it it first started I revved it a few times and it settled down. Recently got worse and is doing it full time. Since intake, plugs and pressure were good I thought it might be injectors. Nope. Changed them out still does it.

Suggestions?

 

[Reloader]

Did you check compression on no 2 cylinder and compare to others? Possible burn’t exhaust valve on no 2 . I assume you swapped coils to see if problem follows no 2 coil pack.

 

[08H3]

I second swapping coils to see if it follows first. Shouldn't really be concentrated on a single cylinder, but check for a massive vaccum leak too. Good luck figuring it out.

 

[Somethingbigandorange]

I did not try swapping coils yet...and now the misfires are on cylinder 5. Would a vacuum leak cause intermittent issues like this? It ran great for a day or so.

 

[Somethingbigandorange]

***UPDATE***

When I plugged in this time the misfires were reading on five, but I kept kicking around what Reloader said about swapping coils. If one is intermittently failing why couldn’t another be on its last legs? So I swapped 5 and 3 and lo and behold now 3 is serving up the misfires.

 

[08H3]

So no (or minimal) misfires on 2 now? Don't understand how that would have fixed itself, but who knows. I would swap the coil now on 3 (formerly 5) to either 1 or 4 and double check whether your problem is still following that coil and at least confirm or rule that out.

 

[Somethingbigandorange]

No, 2 settled down. Keep in mind this was an intermittent issue to begin with. My best guess at this point is that they were staring to fail and I got lucky and caught one doing it. Replaced then all and everything seems fine. As far as I know they were original and I have 190k on my rig so I’m not surprised.

Funny follow up - when I replaced the coils and fired it up initially it was still running rough and I thought “Are you effing kidding me?” Ok, maybe I said that out loud...very loud...anyway I rechecked the connections and I had accidentally bent a pin plugging one in. Straightened it up and everything is good.

 

[08H3]

Awesome! Glad you got it running well again. Fortunately I've never had an issue with a coil, but it is one of the parts I keep on the shelf just in case at this point. Really have no idea what the life expectancy on one is.