Hey all, thanks for checking this out, I'd love any opinions.

So this previous weekend while driving out to grab lunch, I noticed my 3.0 was idling very poorly. It was shaking pretty heavily, and it eventually threw a P0301 code. Let me start by mentioning I have already had the cylinder heads replaced last year due to the dreaded valve recession of 04-06 models. Anyways, I knew this idle shake from that problem, so I nervously limped it home. When I pulled the code I realized it wasn't the cylinder that had misfired during the valve recession time (cylinder 3), but this was cylinder one misfiring. I've been messing with this problem for three full days now to no avail and I'm at witts end. So far I have replaced all spark plugs, replaced all coil wires, replaced coil, replaced iac valve, replaced cylinder one fuel injector, confirmed coil wires are routed to correct spark plugs, checked for vacuum leaks with carb cleaner, and I'm STILL having the same issue. If it has compression, spark, and fuel, why the hell won't this problem go away? I'm really trying to avoid taking it to the shop and being without a ride to work, but I'm all out of ideas.

Highly appreciate any suggestions.

 

This is what i used to do years ago on the brit sports cars.... get one of those plug wire pullers it has the rubber handles run engine at idle and pull the plug wires one at a time if the idle does not change put wire back and move onto next wire. If you have a dead cylinder you will notice no change in rpm.... i even used a timing light to see if spark was getting to the spark plug...

 

I think it's time to do a compression test.

No sense throwing any more parts at it until you know.

 

So I went ahead with the compression test. I'm kind of confused at this point. Here are my readings. This was done on a cold engine and only a dry compression test.
Cylinder 1(misfiring cylinder): 168
Cylinder 2: 170
Cylinder 3: 165
Cylinder 4: 150
Cylinder 5: 160
Cylinder 6: 180

Obviously with Cylinder 4 being the lowest I'd assume that would be the problem cylinder, but the computer ONLY throws code P0301. Is there a chance the computer could be making a mistake and confusing Cylinder 1 wiith Cylinder 4? I can't imagine why Cylinder 1 which has good compression would be the one misfiring.

Yall got any ideas? Thanks!

 

Firing order for 3.0l Vulcan engine is 1 4 2 5 3 6

Misfire codes are set by the Cam sensor so while long odds, it could certainly confuse 6, 1 and 4 misfires, but as said long odds
The computer has the crank sensor for RPMs and baseline timing and the Cam sensor is used for better resolution since it spins at 1/2 the speed of the crank, at 1,000rpms cam is turning at 500rpms, cam sensor is used for better sequential fuel injection timing and for better misfire identification

Not sure if a 2005 Ranger 3.0l will start with Cam sensor unplugged, but give it a try
With no cam sensor pulse the computer may think there is no oil pump either so won't allow startup

If it does start then computer will run in Batch Fire mode, it will open 3 injectors at a time to keep intake full of air:fuel mix, original EFI vs sequential
See if misfire goes away

I would also compression test #4 with a teaspoon of oil added, a WET test, to see if its a leaking valve or rings, psi will go up with oil added, if it goes up to 180 then its rings that are leaking, if it just goes up a little then its a leaking valve