lipartianika

hello

My car is weistec st3, I have repaired the engine pistons on weistec, after that i have problems, Almost everything about the car changed, but Did not help,The engine still works unevenly has missfires,Compression is checked and found to be in the driver's side cylinders (5,6,7,8) has 13.5 and 1,2,3,4 cylinders 12.5

Thanks in advance for your thoughts

Vrodman

My first suspicion would be head gasket slightly leaking. Seems to best explain drop in compression across an entire head. I would think it would a larger drop though than 13.5 to 12.5. Check your oil for any froth or anything unusual. These symptoms are sure signs of cross contamination between air, antifreeze, and oil. Hence head gasket issue. And these could result in misfire. AND . . . .

The head gasket issue could be the result of a failing head bolt or 2. Your compression numbers clearly are for a normally aspirated motor which means M156. 2010 or older by any chance?

Good luck. Let us know if you figure it out

lipartianika

the head gaskets ara new, 12.5 compression ara best for engine but 13.5 is high, i thinkits timing degree problems..

Vrodman

Gotcha. But the consistent 8% compression difference seems strange to me. Did you say you changed pistons recently? I assume, of course, if you did you changed all 8 right with 8 identicle ones? Lol

Cant think of another way to explain compression difference the way you describe other than maybe a valve difference between left and right heads.

Any case, it sounds like you have made large changes to your motor so without knowing all the details its hard to speculate.

Good luck

lipartianika

I changed all 8 pistons & rods new (weistec forged ), CNC Ported Heads and valve polished too new SLS Black Series Valve Buckets changed

shardul

iTrader: (1)

I would recheck the timing and camshaft actuators

PeterUbers

^^this

Actually I have no idea but the people who already chimed in are pretty smart about this kind of thing

gaspam

My experience is if one side is lower then the other, and head gasket has been ruled out, then it's probably cam timing.. ive seen up to 30psi from one side to the other when got timing wrong on old svt

lipartianika

The weistec tells the same, as soon as I find it necessary to write an error