2004 4.0 with 150,000 absolutely reliable miles on it. Always had every scheduled service with premium products. Now I'm feeling a slight engine miss happening only on a cold engine. As soon as it warms up a bit, it's perfect again. Checked with OBD2 and no code appears. Any tips on this one would be appreciated!

 

Most likely a failing spark plug, it happens, even with new spark plugs

 

Thanks for the tip. I may even now which plug, since the last time I changed them I did not do the one back by the A/C evap box. I removed the inner fender liner and I've got just about every socket configuration in the known Universe but could not figure out how to remove that plug. I changed the rest of them but since they all still looked pretty good I just left that one. I guess the time has come . . .

I wonder why it's never thrown a code when it was misfiring? Now all I need do is to figure out how to swap out that plug! Got any ideas? A short socket with a hex end runs out of room before the plug is all the way out. I'm thinking of cutting the back inch off of a socket and welding on a hex-nut collar . . .

 

3/8" universal will usually do the trick, seen here: https://cdn.rona.ca/images/00276661_L.jpg

But just to loosen it, then remove the wrench and universal, and remove socket and plug by hand

 

I tried that. No room for a swivel in there at all. Only way I can even loosen the plug is with a hex-top deepwell socket and an open-end wrench. But a few turns out and the top of the plug hits the A/C evaporator box. The corner of the box comes within less than an inch of the top of the plug. I'm thinking of cutting off the corner with an angle grinder and repairing it once the plug is changed. Of course, cut it a bit at a time to make sure I don't contact the A/C core. That plastic box is probably enough bigger than the evaporator that I can repair it in such a way to allow clearance for future plug changes.

Making that clearance so small was one of Ford's bigger design fails. Except for that one wee detail, I love my 19-year-old Ranger. It still looks nearly new and except for this one glitch, runs and drives like new. Only mods are a 2" cat-back Flowmaster dual exhaust system and Bilstein shocks. At 86 yrs young, I'm still doing all the work on it.

I'll report on however I finally manage to fix this!

 

I have only done spark plugs on two different Rangers with the 4.0l SOHC, 2001 and 2007 if memory serves, neither was THAT tight on right rear, I didn't pull the inner fender either, did pull off the wheel and rubber flap and was able to do all 3 on that side

Not sure why the engine is so close to the heater box?