1. how is it that if the oil cap is open while car is running you feel blowby.... how is that when blowby is gases going past the ring?


2. also vaccum leak will cause rought idle.. but what is it.. is it lack of vaccum or vaccum fighting against positive pressure(air coming in) explain the idle surging

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soon2bdropped &raquo;</TD></TR><TR><TD CLASS="quote">1. how is it that if the oil cap is open while car is running you feel blowby.... how is that when blowby is gases going past the ring?</TD></TR></TABLE>

The pistons oscillating up and down cause the air in the engine to vibrate much like a ported woofer box. The flow that you feel should be going both ways for no net gain. If you have a positive pressure, you could have blow-by.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soon2bdropped &raquo;</TD></TR><TR><TD CLASS="quote">2. also vaccum leak will cause rought idle.. but what is it.. is it lack of vaccum or vaccum fighting against positive pressure(air coming in) explain the idle surging</TD></TR></TABLE>
The vacuum leak disrupts the control loop in the ECU because unexpected air is entering the engine.

 

now thats a tech question. and one hell of a response.