can someone help me with this? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

burnout180 · 03-25-2005, 08:26 AM

I put in a skyline blow of valve and hooked it up to the vaccum line in the back of the throttle body and right when i hooked up the vaccum line at idle the valve was sucked up and was open.
So my question is if the valve is supposed to be open at idle? If not what could be the problem.

I was thinnking that perhaps the vaccum line i hooked it up to might be the wrong one or to strong or it may not be a vacum line at all.

I don't think that the spring is to weak because i didn't even have it hooked up yet and when i put the vaccum line on it opened the the whole way so what else could be the problem.

Anyone have any ideas of what might be wrong or maybe the right instructions as to how to hook up the blow off valve and what vaccum line to use

I don't know anything about BOV's but i was thinking that maybe the when i shift it into gear the valve may go back down.

the head · 03-25-2005, 08:33 AM

yes most BOV are open at idle that is why you want to recirc it because otherwise you have a lot of metered air being vented basically creating a massive leak everytime you stop

Angel · 03-25-2005, 11:01 AM

Yes most traditional bov and recirc valves ( single piston or diaphram ) are open when under heavy vacuum... that's how they work. Obviously this is not an issue on a maf car if you have the valve recirculated as it was designed or if you run an atmospheric valve on a speed density car... either way once you start to make boost they should close. If you want to run an atmo valve on a maf car it is best to run a twin piston valve, there is a secondary piston that remains closed at idle and cruise but opens to vent pressure along with the primary piston. Not too many of thees out there but they do exist and you suffer fewer drivability issues as compared to a typical valve open to atmo.

03-25-2005, 08:26 AM	#1
burnout180 Join Date: Mar 2005 Location: Bahamas Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	can someone help me with this? I put in a skyline blow of valve and hooked it up to the vaccum line in the back of the throttle body and right when i hooked up the vaccum line at idle the valve was sucked up and was open. So my question is if the valve is supposed to be open at idle? If not what could be the problem. I was thinnking that perhaps the vaccum line i hooked it up to might be the wrong one or to strong or it may not be a vacum line at all. I don't think that the spring is to weak because i didn't even have it hooked up yet and when i put the vaccum line on it opened the the whole way so what else could be the problem. Anyone have any ideas of what might be wrong or maybe the right instructions as to how to hook up the blow off valve and what vaccum line to use I don't know anything about BOV's but i was thinking that maybe the when i shift it into gear the valve may go back down.

03-25-2005, 08:33 AM	#2
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	yes most BOV are open at idle that is why you want to recirc it because otherwise you have a lot of metered air being vented basically creating a massive leak everytime you stop __________________ I never knew you could do that with an eggplant

03-25-2005, 11:01 AM	#3
Angel Zilvia Junkie Join Date: Jan 2005 Location: Orlando Posts: 319 Trader Rating: (0) Feedback Score: 0 reviews	Yes most traditional bov and recirc valves ( single piston or diaphram ) are open when under heavy vacuum... that's how they work. Obviously this is not an issue on a maf car if you have the valve recirculated as it was designed or if you run an atmospheric valve on a speed density car... either way once you start to make boost they should close. If you want to run an atmo valve on a maf car it is best to run a twin piston valve, there is a secondary piston that remains closed at idle and cruise but opens to vent pressure along with the primary piston. Not too many of thees out there but they do exist and you suffer fewer drivability issues as compared to a typical valve open to atmo.