4.0 misfire thread

[wilpetty]

I have a 2003 4.0L explorer. I had timing job and new valves put in the car by mechanic. He timed bank 1 180* out, and I retimed the vehicle. I still have a misfire on cylinder 2, and O2 sensor has a stuck on lean code. New plugs, New Wires, New Coil,...Maybe he did not install new valves? What else could this be? Checked the plug, and it looked fine. May buy compression tester to help diagnose if the valve is bent. There is a loud tapping sound on that side..I thought it was an exhaust leak at first, but noise is coming from within valve cover.

 

[donalds]

Your on the right track test compression

 

[wilpetty]

If there is no compression, is it worth it to have the head(s) rebuilt? What is the cost of that if I pull and put the head(s) back on myself? Or should I just throw in the towel and do a motor swap?

If there is compression, then I am totally lost as to what it could be...

If there's anyone in the austin area, I would trade help on this with help on yours!

 

[donalds]

One step at a time
This CAN still be a simple fix

 

[wilpetty]

CLICK FOR VIDEO

click the link and listen to what my passenger side head sounds like. This has to be correlated with the misfire, as it began to do this after I put everything back together. any ideas? should I still check compression, or go ahead and tear down the motor again to inspect what is going on? I removed the cam followers during the timing job, and slightly loosened some of the bolts that hold the camshaft bearings in place, and some did not want to tighten down as much as before, but got snug.

 

[donalds]

If your engine might have a tube (oil spray bars) on the top to lubricate the cams it might be bent or on wrong and rubbing on the cam lobes as they come around. I had this happen to me when I had my new engine put in, and we spent hours trying to figure it out. The only way to know for sure is to take the valve cover off and check.

 

[wilpetty]

I ran a compression test on 3 cylinders and here are the results
Cylinder 1- 100psi
Cylinder 2- 100psi
Cylinder 5- 155psi

I am thinking the passenger side head is toast. Should I buy a rebuilt head? I can’t afford to buy both heads. I’ve never done a head gasket, but I think I can do it with a better torque wrench than what I have. Any recommendations on where I should buy a head? what all should I expect to buy? I am okay with buying the other side head in the future and doing the work, right now it is more about the cost.