This probably sounds dumb, but I'm worried because the homemade leakdown tester I built is giving me results that are TOO good.

'94 GS-R, stock B18C1. I just bought the car as a write-off, it has around 175 K miles on it.

Did a compression test, fully warm, throttle held wide open:

210-210-140-180

Cylinder 3 was obviously the one worrying me, and 4 was a little lower than I would have liked to see. I put a capful of oil into the plug holes of 3 and 4, and re-tested:

210-210-175-210

So after doing this, I started reading up on doing a leakdown test. I used a regulator I had leftover from an old air compressor, and bought the other bits I needed.

I tested Cylinder 1 cold at TDC just to check the tester was working properly, inlet pressure of 100 psi, and it came back with 15% leakage (85 psi).

So I went and took the car for a drive, warmed it up fully, pulled the valve cover and plugs, and tested each cylinder at TDC:

3% - 2% - 4% - 2%

And this confused me even more. On Cylinder 4, I had it one-tooth off of TDC the first time so the engine cranked 90 degrees, and my tester read 20% leakage.

Is there something I could be doing wrong, or some reason my tester isn't working properly?

-Dustin