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Discussion Starter · #1 ·
I have a 2018 Malibu LT with the 1.5 Turbo 4-Cylinder engine. It has approximately 62,000 miles.

Thursday morning I went to leave for work and I started up the car and felt a bad misfire. About 30 seconds later the Check Engine Light started flashing.
I checked the codes with my scanner and found these codes:
  • P0302: Cylinder 2 Misfire Detected
  • P050D: Manufacturer Defined - Cold Start Rough Idle

I had to get to work so I just hopped in my truck and left.

I finally got some time to work on the car this morning and try to figure out what's going on... I went to start up the car to bring it from the driveway into the garage and it was running just fine. Check Engine Light was off and no misfire was felt. I drove it around the block for a little bit and let it idle for about 30 minutes and still no issues.

I figured I'd just try swapping the Ignition Coil on Cylinder 2 to Cylinder 3 to see if the misfire comes back and moves, but when I removed the coil from Cylinder 3 I found the spark plug was broken (See pictures before). The spark plug on all the other cylinders are perfectly fine.

I just replaced these spark plugs about 3,000 miles/3 months ago as general maintenance (manual said to replace them at 60k miles). Used AC Delco parts. I torqued the plugs down to 13 lb ft like my Chilton manual says. And to top it off, this wasn't even the cylinder that was having the misfire...

I guess I'm going to replace them all again today and we will see what happens

Gas Cylinder Auto part Automotive tire Nut
Liquid Spark plug Fluid Gas Office supplies

(Ignore all the scuff marks around the base of the spark plug. The spark plug broke more when I put my socket on it to remove it and the spark plug got stuck in the socket pretty good and I had to be a little creative to remove it from the socket.)

Super Moderator
2016 Malibu 1LT 1.5T/6-speed 6T40
3,378 Posts
I read a bulletin a while ago about bad insulators on some batches of ACDelco plugs. It had the tech inspect for plug damage which you obviously have. Which part number were these Delco plugs?

Without going into a bunch of detail because I can't right now, get those plugs replaced with the current part number, fill up with premium fuel and add a 20oz bottle of techron complete fuel (or whatever oz the bigger one is). Between the repair you noted in your other thread and this hopefully it's that simple and cheap. After running through that tank you should be able to return to regular unleaded.
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