compression test done stock GST 98

[Raybert]

from right to left 163 , 159 , 178 , 175 PSI. Is it ok, if i run with these compressions?
i have got no cat(i have made o2 simulator) ,exhaust blow lots of black somke at high RPM
and at low RPM comes bright blue somke.
sparkplugs are bright brown.
I'm running on 12,5 psi

what should i do?

 

[talonalex92]

Drive it and not worry. Have you performed a leakdown test? Your numbers arent bad at all, but you shouldn't be getting blue smoke. Black just means your running rich.

 

[Raybert]

no i haven't performed it yet, but i will.
but why am i running rich? and why the blue smoke?

 

[Splitpi]

Did you perform the test with the engine at full operating temperatures?

Also pour a little oil, about a half cap full, in each cylinder and retest. Do the numbers increase significantly? If so its most likely your rings or cylinder wall.

Your cylinder compressions are out of spec not because they are low, but because they differ too much from each other. However, I wouldn't worry too much about it. I am in a similar boat with Cyclinder 1 on my engine being out of spec, and I know its ring related. But due to some other ring related events in my life (marriage) I don't have the time or money to do a rebuild.

But don't worry if the car feels fine and pulls fine, don't worry too much about it. Just keep an eye on it. Though I suspect that its your cylinder head valve stems leaking some oil which is causing the spark plug discoloration and sooty exhuast (besides the obvious lack of a cat of course).

 

[1g_tsi_awd]

Blue smoke would mean oil is getting into your cylinder. But your compression is fine, just keep an eye on everything and do a leakdown test and you should be fine.