boyguan

Long story, just got another s2000 and did a compression test.
180/210/220/210.
i tried putting oil in the cylinder and it did not go up. Tried warming the engine and tested and still the same. I have not run a leak down test as i dont have a compressor right now. No CEL and no vibration.

I took off the valve cover to check the valve adjustment and all were <.006". I adjusted them to spec 8-10 10-11 and have not started it since, as i am repainting the valve cover.

is the 180 anything to worry about or just keep driving it?

Zer0ne

Which model year did you get?

boyguan

05 Ap2 with 127k

Slowcrash_101

I would check compression again after valve adjustment. If it's the same you may have a slightly burned valve. It's not going to get better but may not get any worse. Any puffs or pops during idle?

Chuck S

Maximum variation between cylinders is 28psi. 180 + 28 = 208 which is close to 2 of the other 3. I doubt the typical gauge can measure 2psi.

I'd remeasure after driving for a while with the valves at the loose end of the spec. The DBW cars benefit from 0.012" exhaust (a thousandth over) and it won't hurt performance of other years.

-- Chuck

boyguan

Nope, no smoke, no CEL, idles good.

I might stick a borescope down there and take a peek and run some seafoam. i use to seafoam my old s2000 and it ran great with 220 compression across the board.

boyguan

will do,
lets see if this will cure my issue,

s2000Junky

Sounds valve related. Id venture to guess you have a higher leak down on that cylinder either through the intake or exh valves. Could have been just too tight, burned or bent. 180 is pretty low, but not so low symptoms have manifested obviously if your not getting a misfire cel. Your gauge is probably reading a little weak. Wouldn't surprise me if you could add 10-15psi to each of your cylinders on a a more accurate gauge. Stock low mile compression is 230-240psi. I had a cracked ring land and blowing smoke and misfire cel and still read 190psi out of that cylinder just FYI. But a bad valve can reflect a lot of compression loss, more then an F up cylinder in many cases.

boyguan

I expected a bent or burnt valve to show way less than 180 psi. But im not sure how a valve adjustment can really help this unless it was actually leaving it slightly open during its cycle. I am almost hoping it could be some carbon build up on the back of the valve and hoping some seafoam could clean it up.

Slowcrash_101

If the valve has deposits it could keep it from closing fully creating compression loss, especially possible if it wasn't fully closing. FWIW you only need about 130psi of compression for combustion to occur, granted it won't be good combustion, but the the gas will ignite.