Help weird 2014 sonic 1.8l issue

[thanksforyallshelp]

I’m getting a p0420 and the ignition coil pack keeps dying out with a misfire cylinder 1 I replaced the cat, both 02 sensors and the coil pack and plugs twice same issue persisted about a week later car won’t start coil pack bad p0420 misfire cylinder 1. Replaced the flex pipe still replaced the wiring harness still happening. Could it be a clogged fuel injector? Also car has code 52 needs timing belt replaced. Don’t know if this has anything to do with the issue. I don’t have any vacuum leaks that I can see I put a smoke machine on the air intake and muffler got nothing

 

[SkyDog]

The timing belt message doesn't indicate anything's wrong -- just that you've reached the mileage where belt replacement is due. I wouldn't worry about that while troubleshooting the other issues.

As for the misfire, it would be nice if this engine had separate coil packs so you could move them from cylinder to cylinder to verify they're working. But if you're getting a cylinder 1 misfire from two different coil packs and two sets of plugs, I'm inclined to believe the coil & plugs are good. You mention a clogged injector, but that wouldn't be the first thing I suspected because of the code for the fouled cat. Unburned fuel could be fouling the cat, and in order for unburned fuel to reach it, the injector's gotta be delivering it.

I wonder if a bad exhaust valve on cylinder 1 could be causing both the misfire and cat issues. A leakdown test might help determine that. I suspect there are other possibilities, too, but I'm a little too amateur to know them offhand.

 

[TR6Canuck]

I’m getting a p0420 and the ignition coil pack keeps dying out with a misfire cylinder 1 I replaced the cat, both 02 sensors and the coil pack and plugs twice same issue persisted about a week later car won’t start coil pack bad p0420 misfire cylinder 1. Replaced the flex pipe still replaced the wiring harness still happening. Could it be a clogged fuel injector? Also car has code 52 needs timing belt replaced. Don’t know if this has anything to do with the issue. I don’t have any vacuum leaks that I can see I put a smoke machine on the air intake and muffler got nothing

The timing belt message doesn't indicate anything's wrong -- just that you've reached the mileage where belt replacement is due. I wouldn't worry about that while troubleshooting the other issues.

As for the misfire, it would be nice if this engine had separate coil packs so you could move them from cylinder to cylinder to verify they're working. But if you're getting a cylinder 1 misfire from two different coil packs and two sets of plugs, I'm inclined to believe the coil & plugs are good. You mention a clogged injector, but that wouldn't be the first thing I suspected because of the code for the fouled cat. Unburned fuel could be fouling the cat, and in order for unburned fuel to reach it, the injector's gotta be delivering it.

I wonder if a bad exhaust valve on cylinder 1 could be causing both the misfire and cat issues. A leakdown test might help determine that. I suspect there are other possibilities, too, but I'm a little too amateur to know them offhand.

Did you buy an aftermarket Cat or GM? I bought an aftermarket Cat and read after on forums that they aren’t as efficient as GM and can still trigger codes. I also replaced the O2 sensors, plugs, coil, and bunch of other sensors and I still get p0420.