Checked compression with engine cold one year ago. For this test I started at the front and went straight down the line to the back. Results were 370 - 370 - 370 - 290 - 330. Today I tested the engine warmed up and instead of going down the line I tested each cylinder in firing order. For this test the results were 310 - 310 - 310 - 220- 310.
The weird part is that the fourth cylinder tested was low in each test but it is NOT the same cylinder. In the first test the low cylinder was the fourth from front and in the second it was the third from the front. I adjusted the valves immediately before each test.
My question is do I have good compression on all cylinders or bad compression on two or is this a fluke thing that happens?