I have an '02 Alero with approx 170,000 miles on it. This morning, we went to pull out of the driveway and there was a muffled popping noise and suddenly the car was bogging down. The "Trac Off" light came on and "Service Engine Soon" light started blinking. I turned around, got it home, and read the codes...random cylinder misfire. I pulled the plugs and the electrodes were burned back or down to nubs. Not destroyed or anything, just old.

I replaced them with Autolite Double Platinums and confirmed the gap to .043. It idled much better and the enginelight stays off. It still pops every once in a while and it misses under throttle. It is now showing a cylinder 4 misfire code, and the engine and traction lights come on when it starts to miss.

What can I check next. There is good fuel pressure, the plugs are new and wires are good. Thanks.

 

Just some thoughts, I don't know a lot about the 2.2:
Coil pack going bad.
Antifreeze leaking into #4 cylinder.
Plugged fuel injector to #4.
How do you know the wires are good?

 

The coil packs and ignition control module sit directly over the plugs on top of the engine. The coil packs are all self contained within one module and short wires drop directly down onto the plugs. These are not your typical wires. They are a rubber boot roughly 4 inches long with a coil spring inside. The spring pushes up against the coil packs and the top of the plugs when the boots are compressed, rather than snapping onto both ends. I pulled the springs and they are not broken or corroded and measure at zero resistance. There is nothing really to go wrong with them.

 

It was showing a P0304 Cylinder 4 misfire, so I swapped what was already a new plug with a brand new spare and reset the codes. I drove it, and it still misfired under acceleration and when coming up from idle. It seems like I can power through it though. If I give it some gas, it will hesitate and slowly speed up, then all of a sudden you can feel it surge as it picks up on all 4 cylinders.

It is now showing a P0300 Random/Multiple Cylinder Misfire, although it still feels exactly the same as when it was only showing a cylinder 4 misfire. I'm thinking more and more it is the coil packs. Thoughts?

 

I'd get one new coil pack and swap it out until you find the bad one.

 

Change the spark plug boots. Around $20 for all four. My 99 has 170k miles, it would have a miss between 50-55 mph. Change the plugs and boots and it runs smooth again. Also cured a slightly rough idle.

 

Hello i have a 2000 Alero and i changed all spark plugs and got new coil boots as well when putting in the new springs to boot is there a certain way for them to go in i have tried everything i could possibly think of and nothing is working my car is still doing what yours was the only thing i can thank of is maybe i didn't put the spring in correctly so it's not making good contact to the plug and the boot that's why it's miss fireing my Trac light is blinking to and the check engine light came on im stumped please help