OK I'm going to post this here as well as a FB group or two, and r/FiestaST ...Some of my FB group pals have been helpful in giving pointers and that's greatly appreciated!
Background: 2014 with 156k miles, 3rd owner. Timing belt not yet done; I'm still catching up on the new-owner maintenance punch list. There was a rogue P0219A code in the winter which went away on its own, however gas mileage has been 8-10 mpg below average since. Never any indication of coolant intrusion, never any white exhaust or smell of coolant where it shouldn't be.
So a few weeks ago I was changing oil and I decided to also change the spark plugs (I had Motorcrafts on-hand). In doing so I found the boot for cylinder 2 had been decaying into powder where it meets the plug. I bought a replacement boot but like an idiot didn't put what I later realized is the ferrite resistor into the upper boot between the spring and the coil itself.
The car then developed a misfire in cylinder 2. No matter what, putting old plugs back in, moving coils around to other cylinders, the problem followed #2. At one point I was taking out the plug for #2 and found that both the center electrode tip and the entire side electrode had blown completely off. 💩.
Next, I got the #2 injector out as it was suggested maybe the seals were compromised when the spark plug grenaded. The injector was very slimy and dingy looking so I got that replaced as well. At the same time I replaced the upstream O2 sensor that was very chalky-looking.
Still a misfire on #2. And now a P00C6 to go with it (low fuel rail pressure) which so far I'm assuming is related to repressurizing the fuel rail, however it's yet to go away.
My next step so far is to visually inspect the intake valves. P0302 seems like the most common cylinder to misfire from my web searches, and seems highly prone to the majority of build-up from the PCV blow-by compared to other cylinders. Odd if it might NOW be causing a misfire though.
If this doesn't solve my issue, then I have to hand this off to a mechanic shop and fear that the engine is compromised.
This all said, I'm open to suggestions, recommendations, advice, to whether I'm on the right track, or I'm way off and out of my depth. (Very possible.)
Background: 2014 with 156k miles, 3rd owner. Timing belt not yet done; I'm still catching up on the new-owner maintenance punch list. There was a rogue P0219A code in the winter which went away on its own, however gas mileage has been 8-10 mpg below average since. Never any indication of coolant intrusion, never any white exhaust or smell of coolant where it shouldn't be.
So a few weeks ago I was changing oil and I decided to also change the spark plugs (I had Motorcrafts on-hand). In doing so I found the boot for cylinder 2 had been decaying into powder where it meets the plug. I bought a replacement boot but like an idiot didn't put what I later realized is the ferrite resistor into the upper boot between the spring and the coil itself.
The car then developed a misfire in cylinder 2. No matter what, putting old plugs back in, moving coils around to other cylinders, the problem followed #2. At one point I was taking out the plug for #2 and found that both the center electrode tip and the entire side electrode had blown completely off. 💩.
Next, I got the #2 injector out as it was suggested maybe the seals were compromised when the spark plug grenaded. The injector was very slimy and dingy looking so I got that replaced as well. At the same time I replaced the upstream O2 sensor that was very chalky-looking.
Still a misfire on #2. And now a P00C6 to go with it (low fuel rail pressure) which so far I'm assuming is related to repressurizing the fuel rail, however it's yet to go away.
My next step so far is to visually inspect the intake valves. P0302 seems like the most common cylinder to misfire from my web searches, and seems highly prone to the majority of build-up from the PCV blow-by compared to other cylinders. Odd if it might NOW be causing a misfire though.
If this doesn't solve my issue, then I have to hand this off to a mechanic shop and fear that the engine is compromised.
This all said, I'm open to suggestions, recommendations, advice, to whether I'm on the right track, or I'm way off and out of my depth. (Very possible.)
