why does a blow off vavle need to be recirculated?

[cholojr19]

why does a blow off vavle need to be recirculated?

[SpeedRacer1]

Because Nissans run off of MAFS systems. The MAFS tells the ECU how much fuel to burn dependant on the amount of air they think is going into the engine. When you blow off air, it was already metered and so extra gas gets dumped into the engine.

[spider_slayer]

would it be possiable to place the mafs on the hot pipe so one could use an atmospheric bov?

[chickentendah]

would it be possiable to place the mafs on the hot pipe so one could use an atmospheric bov?

Some people on here have done the "blow-through" setup. I believe some of them fried their MAFS by doing so too. Hopefully people will post their first hand experience on the matter.

[Luke]

Some people have used their MAFS in a blow-through setup on the cold pipe. I've heard many things about this like you need at least 10" or something of straight pipe on both sides of the sensor. I also know that the stock SR MAFS is too much of a bottle neck to put inline in the IC piping. Everyone I know who has done this on an SR has already upgraded to the Z32 MAFS. I would also run a catch can setup so there's no oil blowby getting on the sensor.

[cholojr19]

what happens if you dont recirculate the blowoff valve? in other words do you need to?

[Luke]

what happens if you dont recirculate the blowoff valve? in other words do you need to?

you'll experience problems like:-poor on/off throttle response when the bov has opened (after boost).-if you lift the throttle after full boost and coast to a stop, the engine goes rich from releasing the metered air it is expecting. This can cause the engine to stall or get near stalling. If you tighten the bov enough, the SR will run ok.-you'll get backfire and popping in your exhaust, guaranteed.-you'll risk fouling spark plugs much easier-the excess fuel from the atmospheric bov could also melt your catalytic converter and clog it. Some people with atmos. bov's prefer to run a test pipe instead of a cat.

I recommend recirculating, it does make a big difference with performance.
Modified by Luke at 1:46 PM 4/27/2005

[Onizuka]

Its louder when it goes off, your car stumbles (possibly shuts off) when you come to a stop, can cause alot more backfiring when shifting.

EDIT: beat me to it

[Luke]

Here's an old pic of my Greddy Type S bov recirculated to the stock OEM intake tube. I got the hose from a Napa, i think it's a little bigger than 1" (maybe 1-1/4").

[saintsinner]

i remember someone telling me about a black box that hks sells that will help that..not to sure....but im also still trying to figure out if anyone has gone speed density with their sr20 motor.....

[chickentendah]

i remember someone telling me about a black box that hks sells that will help that..not to sure....but im also still trying to figure out if anyone has gone speed density with their sr20 motor.....

You're probably talking about the HKS EIDS which corrects sudden fuel imbalances caused by atmospheric blow off valves.

If anybody is willing to go through that much trouble just to install the EIDS, they might as well go with full fuel piggyback unit, since the installs involve messing with the same wires.

[VitaminT]

HKS also sells a piggy back VPC unit that converts to a speed density.

Oh and to the guy that asked, yes there are plenty of people somewhere that run APEXi PowerFC D-jetro or the AEM EMS.

[saintsinner]

good ****..thanks for da info....