4.6l #2 misfire advice

[jim midd]

My buddy recently gave me his 03 XLT 4.6l. When I got it CEL was on and I pulled 4 codes

Banks 1 & 2 lean
Misfire on 2
And misfire on first 1000 revs.

I'm no mechanic, but I'm pretty handy and not afraid to figure things out. I was able to (I think) solve the lean issues. I found the rubber elbow around the resonator was leaking that brought the LTFT numbers down below 10% on bank 2 and lowered from mid 20s to low teens on bank 1. After that I replaced the PCV valve and that seems to have done the trick. LEFT levels dropped to single digits.

Now the only codes I am getting are the misfire on 2 and misfire on first 1000 revs. Alos, the CEL now occasionally flashes. I never noticed it do that when i was still getting the lean codes

My buddy who gave me the truck was original owner so I have all service records. Looks like he's been throwing money at these codes for a long time. Looks like most of the shops he took to would replace a few parts and clear the codes. I'd like to avoid that as this isn't a daily driver for me, I just need to get it through inspection.

My questions are: could the vacuum leak and constant lean condition have damaged the plug enough to cause a misfire code ( he had all plugs replaced about 10k miles ago)? Does it make sense for me to just pull and replace the #2 plug? And if so Should I just replace the COP at same time? And finally, ive heard the horror stories about these trucks when it comes to plugs and have never attempted to change them before so if this is the right course of action id appreciate any guidence. At this point I'm only looking to deal with the cylinder that's throwing codes (#2). Once I get this thing through inspections it will see very limited use. Thanks

 

[ChrisOIFdoc]

Buy both, replace the plug first, then if needed, the coil. Return the coil if you don't need it, or keep it in case a plug ever launches out of the head. I've had to heli coil 3 and 4 on my truck due to blown plugs. I keep HELI-COIL SAV-A THREAD SPARK PLUG REPAIR KIT and an extra coil in my tool box at all times. Use a torque wrench on the plugs.

 

[jim midd]

Ok, that's kinda what I was thinking. Is it easy enough to access #2? Will I have to remove fuel rail?

 

[ChrisOIFdoc]

No. I've never removed anything to replace plugs or coils. I know a lot of people do, but if you have swivels for your sockets you should be fine.

 

[Bedrck47]

While you are doing the work on the 4.6 Check with the person that gave you the expy and see if the exhaust ports in the Throttle Body have ever been cleaned. If not would be a good time to remove the TB and clean them They tend to clog up more than the exhaust ports on the 5.4 engine. There are some good videos on you tube about cleaning them

 

[jim midd]

Thanks guys. Pulled the existing plug and Cop this morning. Plug didn't look bad ( Autolite) but it was out so I dropped in a new MotorCraft plug and COP. Problem seems to be solved. thanks for advice

 

[jim midd]

While you are doing the work on the 4.6 Check with the person that gave you the expy and see if the exhaust ports in the Throttle Body have ever been cleaned. If not would be a good time to remove the TB and clean them They tend to clog up more than the exhaust ports on the 5.4 engine. There are some good videos on you tube about cleaning them

Thanks. I'll look at service records a little closer and see if he ever had done.