Check your coils.

 

Is there a way to visibly inspect them? I could try to rotate them around and see what codes I get.

What is the proper procedure to test and reset codes to test again? Should I reset codes using my code reader, and turn the car back on and let it idle? For how long should the car run for it to throw the new codes.

 

My moneys on one or two bad coils. Dont tow the car, you can drive on a flashin cel no problem as long as you stay under 3k. You wont hurt the engine by resetting the codes and letting it idle/run. Just dont go over 3k. I recently just went through what you went through.

Reset the codes and run the car and see which ones come back. Right when you get a cel turn the car off and pull the code, or if your scanner can, leave the car on and refresh the "diagnostic trouble codes"to get the code. Once you get the cel it will be one specific or maybe two specific cylinders. If you have one or two misfire codes swap the coils to the cylinders that arent giving you a cel. If the cel follows the coil pack that was originally giving the cel, go buy a new coils for 50 bucks at the parts store and you fixed your problem.

Ex.
I reset the codes and the new cel is for cylinder 1 and cylinder 2
Swap cylinder 1's coil pack with cylinder 3 and swap cylinder 2's coil pack with cylinder 4
Reset the codes
Turn the car back on and let it run.
When the cel comes back and it moves to cylinder 3/4 then you know those two coil packs are bad
replace them and your good to go.

 

Yeah cycle the ignition coil, since you have just replaced the plugs that shouldn't be the issue now. keep the car on idle and take out 1 coil at a time. If your coil works in the cylinder then the idle should become even rougher right when you take the coil out, find the cylinder that doesn't affect the idle when you take the coil out.

 

If they do end up being bad ignition coils just buy a set of OEM k20 coils. Much cheaper than the ap1 OEM

 

Had a customer with an occasional pop from the exhaust. Sounded identical to a burn valve.

Four coilpacks cured it. Two of the packs were dropping out at idle.

While this may not be your problem, just sharing how bad packs can show different symptoms.

 

Is there any risk in pulling the coils while the car is running?

 

Nah, you're not pulling all of them, you pull one and put it back in while the car is running. The idea is to find the coil that made no difference on idle smoothness when pulled, that's the one that's not working.

 

FIXED IT!

Dead ignition coil on cylinder 3. Installed a new one and motor ran perfect. Reset the codes and nothing came back after a 30 minute test drive. Thanks for the help guys.

In case someone in he future sees this thread and your car misfires randomly the next day. It might just be a bad coil like mine.

 

Yes, cylinder washout.

Disconnecting the injectors one at a time is the way to go, whether you are tracing bad coils or injectors.