engine rebuild with problems now, need advice

[240s_are_the_best]

I have a 90 300zx TT and just bought a kit from conceptZ with wiseco pistons and rings, eagle rods, ect. built it, put it in and started it up and noticed it was missing on 2 cylinders, so i checked for spark, and its good, checked the injectors and they ohms out good, took the plugs out and one looks like it was firing a little (end of the plug black) and the other one was covered in oil, and i see what looks to be like pieces of ring laying on the top of the piston... should i pull it and do it again? or say screw it and sell it. i have had the car for 4 months and got to drive it for 2 days.. and spend 2500 in building a junk engine.

[240s_are_the_best]

also what could cause this?

[mrmoose]

do you have any build experience? was the block bored and honed correctly? rings installed correct and not cracked during install? do a compression and leak down test.

[240s_are_the_best]

yes, i have quite a bit of build experience, I had the block honed but not bored, everything is standard size. i have already pulled the engine back out and i am going to tear it down tonight. the cylinder that has oil in it now gave me trouble building it. when i was putting the piston in, i believe it is cyl 5(driver side rear), i broke a ring, so i ordered a new set of rings from wiesco thinking that my ring compressor was the culprit. but maybe there is an issue with that cylinder, and maybe it broke this set of rings. but i think i would have noticed it like i did the other set?

also, the cyl right next to it (3? driver side middle) seemed to be missing also, but the plug on that one seemed to be firing correctly, but when i unplugged the coil it did not change the running of the engine.

when i unplugged number 1 (driver side front) the engine would stumble and almost die. same thing with all the cylinders on the pass side bank.

could it only be missing on the one cylinder (6), and due to the cylinders being side by side make it seem like number 3 is missing also?

[t.mcginley.jr]

Are all the injectors new? If the injector for #3 isn't firing correctly it could be the cause for that cylinder.

For #5 oil on top of the piston means the rings are letting oil by because they are worn/cracked/broken/damaged. The ring compressor itself shouldn't make a huge difference because I use a cheap $5 one and it works fine not just on these engines but on Ford and Chevy small blocks. If the rings are new and already broken, I'd say they got messed up when you tried putting them in.

Take out the pistons for #3 and #5, replace the rings, reinstall and then pour a little bit of WD-40 or light oil into the cylinder. Since the rings are new, it shouldn't let any of the oil past, just pool up on top of it.