To bnr_32,
I'm confusing now X_x for what I heard if the bov spring is soft will cause too much air blow out, this make no air but your ecu will continue supply more fuel due to previous measure of MAP/MAF and eventually running super rich and stall. If bov close too tight will cause flutter before the bov open.
But now u said tighten the bov will make the air turn back to MAF/MAP which ecu will give signal to supply more fuel and eventually cause super rich... U have your point but which one is correct?
Bro,
I'm not a mechanic nor am I an engineer so I'm going to explain to you in layman terms the differences between MAP and MAF. Both do they same thing which is basically to let the ECU know how much airflow there is. Too much fuel, runs rich. But how they go about it is different. If you look at the stock setup, you notice that there are two plugs immediately after the air filters. Those are the air flow meters and its from there that the ECU knows how much air flow to expect. But when you change gears and the blow off valve vents, then you end up with a bit too much fuel; in short it'll run rich sometimes causing it to stall.
The MAP sensor reads the air pressure in the manifold and generally people tap into a vacuum hose to get the pressure reading. This info is relayed to ECU; x amount of fuel for x amount of airflow (calculated based on the pressure/boost).
That's about as basic as I can explain it; of course its not detailed and there is a lot more to it and there are pros and cons for each of them which we will save for your next thread.
So going back to the question of the blow-off valve being tight. When you say tight, there are two ways of looking at it. Some blow-off valves you can adjust the 'tightness' meaning how easily the valve opens. Too tight with stock boost might not be enough to open the valve all the way, and the air must end up somewhere. Lose generally means it'll open easier under pressure which of course equals a louder blow off valve sound.
Another way of describing it as being lose is when the blow off valve won't hold the boost anymore. This basically means that the moment you come on boost the valve tends to leak; allowing the air to escape. This you will definitely notice because you will struggle to build up boost. This will affect the MAP reading. But usually if there is any form of leak then you would notice it when you drive. Does the car come on boost like normal?
Anyways, if you suspect that your car is stalling because its running rich a free and easy way is to check your sparkplugs. See if they are fouled.
---------- Post added at 11:07 PM ---------- 6 hour anti-bump limit - Previous post was at 10:56 PM ----------
1. like bro pimpin said to prevent surging that will damage a turbo in long term and 2. to prevent like what happen to bro pimpin (kereta merajuk) hose piping tercabut heheh and to prevent oem rubber piping from burst (if you still use the oem rubber intercooler piping laa).. so i dont know how to answer your question on too much air blow out and no more air.. why we change to aftermarket bov? 1. because most modern turbo engine have plastic bov that is not durable (but not engine king rb26 stock bov twin cast aluminium bov hehe).. 2. need a stiffer spring rate and adjustable because like bro pimpin laa boost kaw2 1.8bar daily.. when your bov spring is not stiff enough when you boosting high it may leak at the bov.. we dont want that to happen right bro pimpin? sorry bro pimpin have to use u as example coz u are so glamer hehehhehe