So I bought a 4.0 4x4 5 speed a week ago and it had a slight misfire. I changed the plugs, wires, and coil pack everything was tight and to spec. I pulled a plug and it still looked new. Still misfiring but worse… well today I was driving and at this point I’ve had misfire for a week now along with the check engine light, well today it started blinking and the last few days I haven’t had misfire till today. I’ve changed the pcv and the typical ford thermostat housing but that’s all I have changed since I’ve owned it. I leave for school 5 hours away from here in a week so I need help fast asf I’m so damn desperate and I’ve tried everything the codes I’m getting is p0446, the too lean bank one and two (occasionally it’s two) most of time it’s one then I’m getting p304,p0300,p301. I also replaced my tps as well but it was needed and half assed fixed some issues till today. I’ve ran some stp fuel cleaner and was hoping it would clean out the injectors. Nothing changed when I did either. I don’t have any vacuum leaks either I’ve checked everything with brake clean to make sure of it. I was also wondering if a bad o2 sensor would help cause these issues as well with a new evap vent valve since I’m getting a code for it. And would fixing the o2 fix the “leak” sound? It doesn’t have any metals or metallic bits either. It never drops oil either sits right at perfect. I’ve ran the wires from front to back from the evap vent valve and there isn’t any cracks or corrosion. I have what sounds like an exhaust leak sound but only when I give er some beans or a very faint a slight one at idle. Overall it’s a great truck with 180k I’ve put 1000 since I’ve bought it. Gets me anywhere so far. Anyway please please help me like ASAP thank you. At this point I’m ready to run it till I see a piston shoot to the moon but I really need this truck as it’s the only one I have for transportation. And to add on on “cold starts” since it’s summer so to say the rpms sit at normal 1100 then after truck warms up it sits at 800 and fluctuates down to 500 rpms and then back to 800. Again anything helps.

 

Welcome to the forum

One long sentence is hard to read............................lol

You should include the year of the Ranger as well, assuming 2004?????

P0446 is EVAP system code and won't effect operation, but is an emissions code

Check the firing order on the coil pack
3 4
2 6
1 5

NOT
3 6
2 5
1 4

Very easy to mis-wire the 5 6 4 side

Flashing CEL means "backoff the throttle", misfire is bad

P0301-P0306 IDs the cylinder the computer "thinks" is misfiring, its not for sure just a starting point

P0300 is startup misfire, P0316 is random misfires

When there is a misfire code(s) first thing would be to do a compression test
All spark plugs removed
Test each cylinder and write it down

This will tell you if you are dealing with a compression issue(exhaust valve usually) or if you should move on to test for fuel or spark issue

Computer can monitor spark feedback and injector feedback, but can not monitor compression, which is why in the absence of spark or injector codes it should be the first step


O2 sensors need to be changed every 12 years or 100k miles, only sensors that wear out, like tires and brakes wear out
Unlikely to cause misfires

Misfires set Lean codes, not the other way around, so when you have a misfire expect a Lean code soon after
O2's detect Oxygen in the exhaust, not fuel, when a cylinder misfires NO Oxygen is burned up, so that oxygen goes into exhaust and O2 sees that a Lean condition
So cure the misfires and lean codes will go away as well

 

I’ve triple and many times checked the wire order I’m almost wondering if it jumped timing so I’m thinking a timing chain and yes it’s a 2004

 

A compression test will tell you if cam timing is off, one bank will be lower than the other

And that bank would all have misfire codes
So not likely that is the cause

The most common reason for any engine misfire is burnt exhaust valve(s)
A dead spark plug would be next
Injectors, usually not, when there are misfire codes the computer switches to Batch fire to see if misfire(s) goes away

Sequential injection is when each injector opens when its cylinders intake valve opens, this is more fuel efficient
Batch fire, on a V6, means 3 injectors open at the same time, and alternates the 3 each RPM, so intake stays full of the air/fuel mix(like a carb) and each cylinder just sucks in what it needs

So while specific cylinder misfires could be injector related, its a long shot