I own a 2005 Ranger, 4.0 SOHC, 4X4 Automatic with 71,000 miles. Started it up one morning last week and backed it out of my garage. It had a very noticeable miss and within a half mile the CEL came on. I went straight back home and hooked my code reader up. It showed a cylinder # 2 miss fire. No other codes were showing and the truck was running fine when I parked it the night before.

I didn’t have time to mess with it as I had several things going on all at once. (I really thought that things would slow down for me after I retired) Luckily I have a couple of spare Fords to drive. I drove it 7 miles in to town and left it at the local shop where I have a lot of my work done.

Here is what has been found so far (or should I say not found). The above code is the only thing showing (his scan tool is much more in depth than my code reader). The spark plug gap was quite wide so he put 6 new ones in. The color seemed good, about like cooked toast but # 2 plug was a little darker brown. One of the plug wires (not # 2) was chafed so those were all replaced too.

Swapped the coil pack out with a known good unit but it made no difference.

Compression was found to be 170 psi to all 6 cylinders and # 2 passed the leak down test. The fuel pressure was 40 psi at the rail with the key on and 70 psi with the engine running. The fuel pressure passed the leak down test too.

Unplugged the injectors one at a time while the truck was running. # 2 showed no difference in the idle at all so a dirty/faulty injector was suspected. #2 injector was replaced with a new one and the computer code was cleared. The truck ran much better but still has a very distinct miss and the CEL came back on showing the same code.

Sprayed WD 40 all around the upper and lower intake and vacuum hoses looking for an increase in the idle speed but none was found. There was a very clean spot where the lower intake bolts to the aluminum head right above # 2 cylinder. The aluminum was bright and shiny clean right there, indicating that perhaps a leaking intake gasket as everywhere else around the lower intake was dirty except that one spot. Tried spraying starter fluid instead of WD 40, directing it to that clean spot expecting the idle to increase but no joy was noted.

It seems to run better when the engine is cold and gets worse as it warms up.

Whatever is wrong with it seems to be isolated to cylinder # 2. Anyone have any ideas?

 

Was the intake manifold leak test performed After the engine was warmed up & missing?
What was the bank 1 fuel trim showing?
Any unusual noise on the top end around #2 cylinder when listened to with a stethoscope?

 

I'm not sure if it was warmed up good or not. I will ask about that. I don't know what fuel trim means so I can't answer that one. All they said was that it had good fuel pressure, 40 psi with the key on and 70 while it was running. They did tell me that the engine was running quiet with no unusual valve noise so I am going to assume that they listened with a stethoscope. They took my truck to another local shop this morning where one of the mechanics is more knowledgeable on Fords. I haven't heard back from them today so I would assume that the other shop will have to work it into their schedule.

 

The verdict is in. The initial problem was a dirty (or dead) fuel injector. The secondary issue was defective new in the box spark plug wires. Runs like a champ now and has even stopped spark knocking. I'm a happy camper. Thanks for the advice.

 

Ok, good find, fix, feedback & to hear all now seems well & your on the road again.