sputter when I remove oil cap?

[se7en77]

Is it normal for a car to sputter when you remove the oil cap while its running?

[AZhitman]

Is it normal for a car to sputter when you remove the oil cap while its running?

Nope. Time for a compression test.

[sx moneypit]

It used to make my 280z idle kind of weird,but it did not sputter.

[AZhitman]

May well be an issue with the PCV. Test it... a bad PCV can affect fuel economy.

[se7en77]

compression check is ok within range....yeah i was leaning towards a bad pcv but i heard its a pita to get to so I was puttin it off.....but I guess I'll have to check it.....Thanks

[seang]

Alot of air travels through the crankcase via the PCV system. It is very important that it works right because you don't want alot of pressure to build and fight against the pistons as they travel downward.

All the fresh incoming air for the PCV enters through the breather on top of the valve cover (this must be clean and free flowing). The actual PCV outlet and valve (on ka24's) is under the intake manifold somewhere near the oil filter.

The pistons hit TDC faster than they hit BDC, and this is the cause of the pulsations you feel when you remove the filler cap on a running engine. Some engines like v12's might have smoother charictaristics here, but for our flat plane four cylinders, it's just two up and two down. You could imagine how drastic this effect is in a big single cylinder engine.
Modified by seang at 8:09 PM 12/14/2009

[sx moneypit]

The piston moving down on 2 stroke engines pressurizes the combustion chamber.They dont use turbos or superchargers.