Constant misfire #3

[AlienfromUranus]

I have a 2006 Expedition 4.6 3v XLT misfire on #3, rough idle have replaced spark plug, coil and injector and no change. While running timing is erratic and reading from MAF is near 0 at all engine speeds

 

[AlienfromUranus]

More info swapped spark plug coil and fuel injector from #3 to #1 no change still misfire #3 compression is 149 #3 and 151 on #1 o2 sensor Bank 1 sensor 1 showing 0.020 v Bank 2 sensor 1 showing 0.700v both are new OEM sensors

 

[Yupster Dog]

still misfire #3

First thing comes to mind is heater hose tee leaking on #3. Second is check wire harness for coil on #3.

 

[steelnewfie]

Not sure if an injector could cause that. I'd replace all plugs on that cylinder bank. Especially 4. It can cause errors on other cylinders (I found out the hard way). Also torque those puppies down good. Check ALL plugs are torqued down actually... they tend to back out sometimes (my 06 both banks it happened) Run a can of fuel injector cleaner / seafoam as well. Use Motocraft coil packs and plugs from Ford it will save you headaches in the long run. Once I fixed my misfires I got a tune and she idles, runs and pulls perfectly. Keep at it, they are good engines.

 

[steelnewfie]

Oh, and your cats are probably blocked solid. Once I fixed that everything got much better.