SPECS
2007 Ford F150 5.4 Liter Triton V8 Flex Fuel
156,000 MILES

VEHICLE BACKGROUND
Regularly scheduled, full synthetic oil changes.
Previous acceleration problems between third and fourth gear, but no codes thrown at that time (seemed to improve after I cleaned the mass airflow sensor but never went away entirely. heard there was flash code to fix it but they’re all related to the 06’ models and the dealership says it can’t flash codes not meant for my specific year. Whether that’s true, I don’t know, I only know Ford dealerships are the only ones with access to WAVES, or whatever that internal ford program is).

MY MORE IMMEDIATE ISSUE...

First drive (roughly ten days ago)
-drove several miles without issue about an hour prior to start of symptoms (this driving included highway speeds). No issues.
-made three quick store stops (as in no highway speeds achieved between the engine's off/on)
-was two miles into my drive home when the engine light illuminated. The engine light was accompanied by mild shuddering and loss of power upon normal acceleration.
-I risked continuing home, accelerating at a much slower rate, and low and behold, five to ten minutes later the engine light, along with all other symptoms, went away. However, this only happened after achieving highway speeds for a few minutes. When I slowed down to park, etc, the symptoms didn’t return.

Second drive
-one short trip to the store and back (short as in under 10 minutes and 30 miles per hour), no symptoms.

Third drive
-truck sat parked for three days prior (which included a huge temp drop to 20 degree whether)
-this time symptoms began upon start up (including the engine light, which remained on)
-drove to the same store and back (less than 10 min/30 mph). Never got to highway speeds and symptoms worsened as I went.
-the shuddering and engine noise (which I’d describe as louder overall performance combined with a rhythmic thwacking) increased the slower I drove, so of course it was loudest at stop signs and when I went to park. In fact, I got the distinct impression that if I made a complete stop the engine would shut off, however, it never did, but it did get louder.

As of today
-haven’t driven since (two days now), so no diagnostic yet to see what code it might throw.
-this morning I found a slow oil drip at the oil pan release nut. when I checked the stick, it was s 3 quarts low (in other words the oil ended half way up the oil stick’s grid).
-I plan to change the oil filter and oil before heading to get a diagnostic, just incase the issue is oil related (didn’t want to kill it just trying to get to the auto shop). It’s a few hundred miles past due anyway.

Any guidance would be appreciated.

 

You need to get the codes read and report back.

 

Codes scanned for sure... Loose assumption would be misfire problem, but needs the codes to help further.

Last time plugs and boots were changed?

 

Ya, code called it. Cylinder 4. Sure enough, water was in the boot and the coil was burned up. Squared that away and juiced the oil viscosity (5w30 up from 5w20). Real quiet under the hood now. Bad part is, C4 was likely dumping fuel into the cat converter for a few days. It's not shot yet, but it announces itself with an occasional knock now, mainly under driver seat. Consensus is 6 mos or so left. I heard about some guys who would cut it right at the O2 sensors and weld a universal into place. Brand new cat around here is $596, weldings like a third that.

Any experience with that procedure?

 

If it is running good now I would not worry about the catalytic converter unless it starts throwing a p0420 code. The front converter is angled between the in and the outlet. There is a weld in one you can get somewhere from eastern catalytic I believe but I would wait until it proves necessary.