2009 Escape XLT FWD 2.5 non-hybrid 150K mi

Background:
This is long, I’m sorry. Hoping to address as much as possible in the first post.

Bought with around 100K, always idled a little rough, assumed it was PCV/Oil trap related and since some genius thought it should go behind the intake, I delayed changing it.

Fast forward a bit (~20-30K mi) and I got CEL cylinder 1 misfire. Thought I should change the plug’s as that hadn’t been done since I bought it. Noticed oil on plug 1. Wasn’t going to do the valve cover gasket yet. Cleaned up the oil, changed the plugs and all was back to “normal.”

Another 20K mi and back to CEL cylinder 1 misfire, along with occasional vibration while cruising at 55/70mph. Got home, pulled the COPs and oil in wells 1&4, at least 1/4 the way up the boot…time for the valve cover gasket, pcv, oil trap, intake manifold gaskets, and fresh plugs.

Things improved, but not as much as I expected. Left the COPs at the time, but changed them a few days later when CEL returned accompanied by the occasional flashing CEL and heavy vibration. Tried moving plugs, COPs, and injectors around, but no change to the cyl 1 misfire.

New COPs seemed to help, but all symptoms eventually retuned. Now also getting P0316 (misfire on first 1000 revolutions), but only when cold. Took it to Ford (yes, I know) and the tech, who also was the shop foreman, says that it’s the head gasket. I asked if he conducted a leak down test and he said that it wouldn’t have told him anything different 🤔 and that he pressurized the cooling system and as the engine cooled he saw a small amount of coolant entering into cyl 1 via a borescope.

I asked how confident he was that it was the head gasket and he said that is the most likely cause, considering the coolant in cyl 1. We went back and forth a little and clearly he was either overworked, lazy, or just plain inept.

They wanted $2700, I passed.

Back to the garage with a head gasket, exhaust manifold gasket, timing kit, thermostat (its always run a little cold), water pump, fresh coolant, etc…and this time the radiator is coming out so that stupid middle bolt on the intake won’t be as much trouble.

The head and visible areas of the block/cyl walls appear crack free. One exhaust valve on cyl looks like it was steam cleaned, but no visible chips or cracks.

Button everything back up, reconnect the battery, do the coolant dance, drive it, and it feels great! Until the CEL starts flashing and the engine lugs…misfire on first 1000 again, misfire cyl 1 again.

got out the noid light and injector and signal to COP on cyl1 acting normally. Ran a compression test and cyl 1 lower than all the others, 150, 160, 165, 160. Did a leak down, cyl 1 fails miserably and the rubber glove taped to the exhaust pipe blows up. <—worthless information according to the ford shop foreman.

So I get 2 new exhaust valves, valve stem seals, some grinding compound, another set of head bolts, TB cleaner, MAF cleaner, and another head gasket.

With the 2 old exhaust valves removed, the steam cleaned looking one is slightly smaller in diameter than the other, 🤞 that this is the issue.

Fire it up, starts out a little rough, then smooths out some, looking up!

Nope, SSDD. I haven't performed another compression check and leak down yet, will do so tomorrow. But I did do a lot of monitoring to see what might be causing issues.

While driving, all seems ok until the CEL starts flashing and the motor lugs. When this happens, BOTH O2
sensors drop to 0.02v and don't change any. Whether I keep my foot where it is, floor it (which sounds and feels like a helicopter is buzzing me), or completely taking foot of throttle they stay at 0.02.

Now if this were accurate, I think the exhaust temp would spike, as 0.02 should mean that the engine is ruining lean, but it doesn't increase.

If holding steady speed (a bit more throttle than moments ago) or flooring it while the CEL flashes, eventually "things clear up”, the O2 sensors are reporting reasonable data, and the car gets a burst of energy, the helicopter leaves, and a few seconds later the CEL stops flashing.

It doesn’t always happen, although getting more frequent, and most commonly happens after reaching cruising speed and maintaining steady throttle, and lasts from 20-40 seconds and then magically disappears

the only substantial change to anything I’ve looked at in real time is the simultaneous drop in O2 sensor voltage to 0.02 when the lugging and flashing CEL occurs and the then simultaneous return to reasonable O2 sensor readings and engine power.

I’ll do fresh compression and leak down tests tomorrow and swap O2 sensors with some new ones and report back.

Any other thoughts would be greatly appreciated.

Sean