Do the MK3's have blow off valves?

born2drv · 01-29-2006, 11:20 PM

that one pictured in the ebay auction is the bypass valve, yes.

a blow off valve vents to the atomosphere,where as a bypass valve re-routes the metered air back into the intake. that is why some people experience a tendency for the engine to want to die when the blow off valve vents out to atmosphere --- because all that metered air is now lost and the engine is flooded with too much gas.

to make the BOV function like toyota engineers intended, you will need to re-route that blown off air back to the intake pipe. the Greddy RS BOV has an optional flange you can buy that you can then mount a hose to. This is the setup I will be running.

Burn N' Up · 01-30-2006, 07:06 PM

I never had a probelm with venting into the atmosphere causing flooding to the point of a power loss but then again I don't have a AFR sensor on my car... yet.

The whole blowing off into the atmosphere idea comes from the big time turbos dumping huge amounts of boost off everytime you shift. If you look at the point of return on most bypass valves, like in your supra, its AFTER the AFM. Lets say you were running a substantial amount of boost, now you shift, and a shit load of unmetered air just got bypass dumped into the intake side leaning out your mixture and possibly causing all the problems that come with that. Now again thats with a bigger motor so its not that crucial an item with the typical 6-8lbs in a MK3. The big idea is that too much fuel might make your car sputter a bit but by then your already back on the gas shifting slamming more air into the throttle body and its not a concern. Too much air on the other hand, that means you lean it out and possibly melt something. =O

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01-29-2006, 11:20 PM	#1
born2drv Stock Join Date: Oct 2005 Posts: 13	that one pictured in the ebay auction is the bypass valve, yes. a blow off valve vents to the atomosphere,where as a bypass valve re-routes the metered air back into the intake. that is why some people experience a tendency for the engine to want to die when the blow off valve vents out to atmosphere --- because all that metered air is now lost and the engine is flooded with too much gas. to make the BOV function like toyota engineers intended, you will need to re-route that blown off air back to the intake pipe. the Greddy RS BOV has an optional flange you can buy that you can then mount a hose to. This is the setup I will be running.

01-30-2006, 07:06 PM	#2
Burn N' Up 3" Exhaust Join Date: Sep 2005 Posts: 238	I never had a probelm with venting into the atmosphere causing flooding to the point of a power loss but then again I don't have a AFR sensor on my car... yet. The whole blowing off into the atmosphere idea comes from the big time turbos dumping huge amounts of boost off everytime you shift. If you look at the point of return on most bypass valves, like in your supra, its AFTER the AFM. Lets say you were running a substantial amount of boost, now you shift, and a shit load of unmetered air just got bypass dumped into the intake side leaning out your mixture and possibly causing all the problems that come with that. Now again thats with a bigger motor so its not that crucial an item with the typical 6-8lbs in a MK3. The big idea is that too much fuel might make your car sputter a bit but by then your already back on the gas shifting slamming more air into the throttle body and its not a concern. Too much air on the other hand, that means you lean it out and possibly melt something. =O