2007 Misfiring

[Eagles Driver]

Recently had the explorer inspected when two days later (7/4) the check engine light started blinking. Acceleration was slightly sluggish, figured it was plugs, researched changing them myself, realized I could be in way over my head (tales of special tools and busted plugs...), panicked and got a quote from the CarX Auto Service (San Antonio 78240) across the street from my apartment. Over the phone I was quoted for plugs, dropped explorer off and before long the calls started coming ('well we got the special plugs out without busting any but your injector is filthy....cleaned the injector but we noticed the coil needs to be replaced..). since then she's been running clean, no misfires until two days ago: again blinking check engine, then went to solid, sluggish, can feel the misfire. now she starts and you can feel the misfire (no big shudders, just slight misfire) but only in idle. went to autozone to get the TPS test done and results:

Cylinder misfire detected #4
Probable cause:
ignition system: fault spark plugs (new), ignition wires
wires: coils (new)
vacuum leak
injector fault (cleaned)
high or low fuel pressure

should have but didn't get wire harness changed. All work done on 7/4 is ''covered'' under 12 mon/12k mile ''warranty'' but i read that about the same as anyone ending any sentence with ''trust me''. finally; not sure this has anything to do with above but noticed a slight 'tapping/ticking' sound months ago after turning her over. sound goes away around 2k rpm or a few minute of driving.

2007 Ironman
V8 281ci 4.6L 4WD Automatic
109K+ miles

 

[Explorer_PL]

I would check the plug and see if you can remove it easily. If they replaced all, they all should come out easily. Maybe they did not ...

 

[Boomyal]

Check to see what plugs they used!

 

[Eagles Driver]

Thanks for suggestions, crew. CarX had replaced coil number 2. Their scan showed misfire in cylinder #4 also, they suggested replaced coil in 4. Currently replacing.

 

[thebrakeman]

Coil is easy to replace. Do it yourself.
As far as the ticking on cold startup, that's a well-known common issue, and is an exhaust leak. After a couple of minutes, the exhaust system heats up and seals itself.
If it gets worse, or does not go away, it could indicate that 1 or more manifold bolts have sheared. That may have already happened. As long as you feel no significant loss in power, and no significant increase in fuel consumption, probably fine. If you see/feel either of those, might be time to have those bolts checked for fracture.