Hey guys, I recently picked up a 2004 Mercury Mountaineer, 4.0 with 113,000 miles.

OBD reader says misfire on 3 cylinders.. Installed new plug wires first.. nothing.. going to install plugs next when she is cold. Now, am I really looking at replacing the coil pack to end the misfire codes? She likes to buck and shake and idle around 400 rpms.. I know that is too low..

I figured someone here has already been down this road and I'm looking at how much this might cost.

Many thanks guys!!

 

Which 3 cylinders are listing a misfire? If all 3 cylinders are on the same bank, it may be something other than plugs and wires, such as a vacuum leak or fuel injection wiring harness....

-Rod

 

Or maybe timing chains. Which was the case with mine.
Same symptoms as mine. Mine had about 117k miles at the time.

 

I have a 94 explorer I had to replace the brain. The camshaft position sensor. Egr valve.about sixteen hundred in parts and labor. The c.e.l. went out long enough to get it smoggged.after finding out the c.e.l.t burned out I replaced I replaced it. It came on and stays on .I performed the e.o.e.r. test and got a 337 code. I was going down the road at 45 mph when I noticed the cel light had gone off this lasted 20 sec or until I decelerated and it came and has stayed on.the question I have is this is that 337 code being caused by the egr valve or some other vacume problem? I just hate the process of elimination that is expensive. Any advice is appreciated greatly.

 

The code 337 points more to the DPFE sensor than an EGR valve itself. The DPFE was actually a pretty common issue on older Fords.

-Rod