Alright so I bought a 2009 Ranger from an auction for cheap, knowing the CEL was on and IT ran a little rough. I got my scanner out and found it had 2 codes, P0301 and P0303. I put new plugs and wires on it and cleared the codes. Went out for a drive on a stone cold engine and the P0301 went away, but the P0303 came back. I cleared it when the engine was hot from the drive and drove it again, but obviously the difference is, this time the engine started out hot, not cold. Did the same loop and found no codes. So it only misses on #3 when cold, clearly. What could this be? I definitely notice it when it fires up cold since it stumbles while starting and the truck has a minor shake.

When I took the old plug out on #3, it smelt of raw fuel pretty bad, I could also smell fuel in the exhaust too. It's a 2009 4.0L SOHC with only 98,000kms(60,000 miles). Please help!

Thoughts:

*How is the plug wire on the cyls in question? This because, it's harder to fire a cold spark plug than a warm one. Note: unless the wire is cut/torn/burnt to an exhaust manifold, the old "look under the hood with engine running at night for arcing" test is not a reliable test. The insulation will conceal a failing conductor. Either use your ohm meter or move the wire to another cyl and see if the problem follows to verify the wire for integrity.

*Is it consuming coolant? This because, if for some reason coolant is entering the cyls in question then it's possible that the moisture will not allow those spark plugs to fire until it drys up, typically when engine heat does the job.

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2004 Ranger FX4 Level II, 5R55E, Sonic Blue Pearl

Proudly JAP/RICE free since March 2000

Well they are brand new plugs as well as wires so that shouldn't be an issue. But in case that there is a wild chance I got a defective wire and/or plug on the same problem cylinder, I'll swap them to cylinder 2 and check. I'll also do a compression test.

Did you get OEM Motorcraft plugs and wires?

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93 Ranger XL 3.0 V6
-Tint, wheels, K&N filter, Flowmaster super 44.
04 Mustang GT Vert.
-Tons of mods, supercharged 392/393

have you checked the injector?

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1999 Ford Ranger 3.0 auto 4r44e 4x4 XLT Off-road package 4.10 open extended cab pioneer head unit. 12" Crossfire sub with Alpine amp. 16x8 DC2 Rims -12 offset. Gibson dual catback exhaust. Engine swapped from 2005 Taurus with 140K

No. Just went to an auto parts store and got supposedly good quality stuff.

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How would I check it? I think it's working since I do smell raw fuel.

you can check the resistance with a multimeter or i will advise you to watch this

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1999 Ford Ranger 3.0 auto 4r44e 4x4 XLT Off-road package 4.10 open extended cab pioneer head unit. 12" Crossfire sub with Alpine amp. 16x8 DC2 Rims -12 offset. Gibson dual catback exhaust. Engine swapped from 2005 Taurus with 140K

That could be the issue. These trucks don't like anything else other than Motorcraft or Autolite plugs and Motorcraft wires.

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93 Ranger XL 3.0 V6
-Tint, wheels, K&N filter, Flowmaster super 44.
04 Mustang GT Vert.
-Tons of mods, supercharged 392/393

Try getting that additive for the fuel that cleans out the fuel injectors or seafoam and see if that helps

Swap injectors- take the #3 injector and move it to a different cylinder putting that cylinders injector onto #3.

Start engine cold and take it on your loop. If the misfire returns at #3, its likely not the injector. If the cylinder that you moved #3's injector to gets a misfire code, that injector sticks open and dumps way too much fuel into the cylinder. You can try to clean it, or just replace it.

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s