2013 Toyota Corolla error codes P219A, P0301

I am working on a 2013 Toyota Corolla that has a check engine light on. When I used an OBD II code reader I got the error P219A & P0301. If you google these codes you will find a detailed description of what these codes means. 

I first tried to tackle P0301 which is a misfire on cylinder 1. I checked the wiring going to the cylinder and it was fine. I pulled the ignition coil in cylinder 1 and I did not find any obvious defects or damage to it. The spark plugs seems normal too but it was kind of old since it has been in the car for the last 2 years, but they seem to be fine still. I figured that it might be the fuel injector. 

Fuel injectors are not exactly cheap. I decided to call a used parts dealer/distributor in Rancho Cordova in northern California and found used ones for $20 a piece. I ordered them and it took a day to receive them via mail. Before installing the replacement injectors I bought new rubber rings & seals. After installing the replacement injector I reset the code & drove it for about 5 miles. After 5 miles the check engine light came back on & so used my OBD code reader to find out the code. It showed P219A & P0302. Now the miss fire is on cylinder 2. I was a bit puzzled as to why the problem is now on cylinder 2. I decided to pull the injector for cylinder #2 and cleared the "seat area" where the inject goes in. I reset the OBD2 then drove it for 30 miles then turned off the engine. When I turn the engine back on the check engine light came back on. This time it only showed P219A. I drove it for another 30 miles & check the OBD2 to see if there are any other codes to popped out. It only showed P219A. 

I was feeling a bit puzzled this time and was tempted to just throw new parts to it hoping I might eventually fix the problem. But this technique is expensive and so I decided to diagnose to narrow down there the problem might be at. 

I decided to check the compression on each cylinder using a compression test tool. The following are the results: 

cylinder 1 - 133psi

cylinder 2 - 90psi

cylinder 3 - 140psi

cylinder 4 - 150 psi

I tested the compression in cylinder 2 thrice & got the same results-90psi. This made my heart stop because to fix a low compression in a cylinder is difficult. I have heard other mechanics having to remove the cylinder head of the engine to replace parts in it. 

According to the Toyota mechanic's bulletin the Toyota Corolla 2012-2013 had a problem on compression loss due to the exhaust valve being defective. 

I have never replace a cylinder head of a Toyota Corolla or any modern car. The only time I replaced a cylinder head was from the engine of an old Volkswagen bus.

I better learn the cylinder replacement for a 2013 Corolla so that I can fix this car.