Our friends' 2012 Sonic (NA 1.8 l automatic c. 120K km) has been marooned out at their daughter's family home in a small town near here. It would start but ran very poorly, and the check-engine light flashed, indicating a misfire.
I advised them not to drive it back, as the misfire could quickly ruin the cat.
I was finally able to get out there this afternoon. Removed the original plugs (NGKs) - all four were black and wet, one of them dripping with oil, and another moderately covered with oil. The electrodes didn't look too bad though. I figured the oil seals at the bottom of the spark plug wells were leaking. My friend had bought new AC plugs in advance, and we installed them. The car started fine, but ran roughly, again indicating a misfire.
My friend ran over to a local parts store, which fortunately had the coil pack in stock. (It's a single unit on the Sonic, so I couldn't troubleshoot by swapping individual coils to see if the misfire followed the coil.)
Anyway, the new coil pack fixed the misfire, and the car runs well now.
But, I'm concerned about the oil leakage.
I think it's quite possible the valve cover gasket failed (it's a one-piece unit which includes the four spark plug oil seals), which caused the plugs to get saturated with oil and misfire, which stressed the coil pack, causing it to fail. If that's the case, it's important that we change out the VCG as soon as possible.
Further, I watched a YouTube video later, which showed that the PCV valve is integrated into the plastic valve cover. I hypothesize that if the PCV valve gets blocked, the blowby pressure could blow out the spark plug gaskets, resulting in oil-fouled plugs and eventually another failed coil. Make sense?
Who's got experience with this engine? Apparently the normally-aspirated 1.8 was also used in the more-common Cobalt.
Does it make sense that a blocked PCV valve would cause this chain of events, or is it more likely just coincidence?
If the PCV valve portion of the VC is blocked or even iffy, can I clean it with TB cleaner, etc., or is it best to change the VC out?
Thanks in advance for your thoughts.
I advised them not to drive it back, as the misfire could quickly ruin the cat.
I was finally able to get out there this afternoon. Removed the original plugs (NGKs) - all four were black and wet, one of them dripping with oil, and another moderately covered with oil. The electrodes didn't look too bad though. I figured the oil seals at the bottom of the spark plug wells were leaking. My friend had bought new AC plugs in advance, and we installed them. The car started fine, but ran roughly, again indicating a misfire.
My friend ran over to a local parts store, which fortunately had the coil pack in stock. (It's a single unit on the Sonic, so I couldn't troubleshoot by swapping individual coils to see if the misfire followed the coil.)
Anyway, the new coil pack fixed the misfire, and the car runs well now.
But, I'm concerned about the oil leakage.
I think it's quite possible the valve cover gasket failed (it's a one-piece unit which includes the four spark plug oil seals), which caused the plugs to get saturated with oil and misfire, which stressed the coil pack, causing it to fail. If that's the case, it's important that we change out the VCG as soon as possible.
Further, I watched a YouTube video later, which showed that the PCV valve is integrated into the plastic valve cover. I hypothesize that if the PCV valve gets blocked, the blowby pressure could blow out the spark plug gaskets, resulting in oil-fouled plugs and eventually another failed coil. Make sense?
Who's got experience with this engine? Apparently the normally-aspirated 1.8 was also used in the more-common Cobalt.
Does it make sense that a blocked PCV valve would cause this chain of events, or is it more likely just coincidence?
If the PCV valve portion of the VC is blocked or even iffy, can I clean it with TB cleaner, etc., or is it best to change the VC out?
Thanks in advance for your thoughts.