P0305 code has me puzzled and needing help. First Post Here

[BULLA]

I have a 2002 ranger with the 4.0 auto that was given to me by my brother. He lost the key and after about a year of sitting he gave it up. So I had a key programmed for it and it wouldn’t start. Through some troubleshooting I found the fuel pump was out. Replaced fuel pump and it fired right up. Now my dad had told me it was leaking oil and boy was it. But it also had a miss. So I decided to pull it in the shop to change the valve cover gaskets. Not the hardest but not the easiest job! Well I figured since it had the miss I’d also replace the spark plugs and the injectors. Figured one of those would be my culprit. Long story short I got it all reassembled and the moss is still there. Now I almost could guarantee which cylinder was gonna be the problem it the beginning cause #5 had lots of carbon build up in the intake and that spark plug looked the worst. Now since I had cleaned everything and new injectors and plugs I started pulling wires off of the coil. Sure enough number 5 wouldn’t change a thing. So I pulled that plug and it was wet. At this point I thought it didn’t have fire to that plug. So I cranked the truck with that plug out and there was plenty of fire. So I opted to pull the number 6 also. I checked it for spark and it was the same. Then I decided to do a compression test. Both cylinders tested 150psi. I reassembled everything and swapped the #5&#6 plugs just for good measure and no change. So now I’m wondering could it be a bad injector that just so happened to be on that same cylinder that originally seemed to be the problem. Trying to be through. I have read of a leak down test though never performed one. Guess I need to look into it.

 

[franklin2]

I wonder if #5 plug would still be wet if you unplugged the wire to the injector? Also check the injector wire carefully, they feed it 12v all the time on red wire, and the computer grounds the other wire to fire it. #5 injector wire is supposed to be tan/black. Make sure this wire is not rubbing ground somewhere. Here's a diagram of the injector wiring.

 

[BULLA]

Thank you. I did read this when researching and was headed there next. Just glad someone else is here n same page as me.

 

[BULLA]

Well I think I found my culprit, I tested that cylinder again after running the truck with the spark plug removed and only got 130# of compression. So I took the compression tester tool and removed the gauge and began to blow air into the cylinder and it had blow by so much that putting a bag on the oil filler cap it would move the bag. Also my best guess for this scenario was that when I had done the compression test the first time it was after I had driven the truck and parked it and checked it cold the next day and maybe after fouling the plug the cylinder was wet enough it gave that 150psi reading. Cause tonight it did almost that except the first crank not as high. But I re checked it about 3 times and it would get a little lower each time. But the 130 was the lowest.

 

[JohnRgr2005]

Hi Guys,

I have a 2005 4.0 and wanted to Thank Mr. Franklin for posting that diagram for my possible future use.

Can you please confirm the diagram is same for 2005 4.0 SOHC.

Learning Every Day.

 

[franklin2]

2005 injection wiring is similar.

 

[Lawman534]

Do you have any updates on this problem. I am having a similar problem on mine, just with a different cylinder. I believe I have a valve that is getting stuck, but not stuck every time. I also get good compression. Maybe thats why only an occassional misfire occurs?