[Br@ndoM@n]

pretty simple ya got a broken piston ring.

 

[Br@ndoM@n]

You should of done a compression check which you did. Then did a leak down test on that low cylinder that would of told you where the leak is.

Also every 4 banger I have ever worked on that had cylinder problem has always been on number 1 for some reason.

Also looking at the pistons wont really tell ya crap since the rings are compressed. unless you can see a scruff mark but you dont alwasy do. when i rebuilt my 4ze1 motor I already figured I had a broken piston on cylinder one. pulled head off and everything appears to be good but when I pulled piston out I got some peices of piston rings in my hand. Mostly the oil retention ring. It had broken and the excess blow by and heat had made the carbon weld the rings to the pistons. not really weld but got hard like rock and helpped hold the rings on.

In short I am sticking to what I posted earlier. U have a broken ring on piston 1. Same thing happened to me. seemed to run ok but when I pulled spark plugs all were clean except for cylinder 1. then did a compression test on all and got something like 32 150 164 159. Did a leak down test and head wasnt the problem. Then pulled the motor and started tearing it apart. Ordered the parts to rebuild it, didnt order a rebuild kit cause I could peice together a higher quality of parts for the rebuild then what any kit would have. cost probably 2.5X as much the kit but the parts I got were "upgrade" from stock.