Bov Noob question

[tsuga]

so on my booted 89 probe i just noticed that the bov ejects gas right back into my intake piping or an internal system if you will.

so i decided to make it external when i started my car i noticed that my rpm was fluctruating and i thought "well thats not good"
so i shut the car off and covered the bov exit pipe and noticed that the rpm went back to normal.

now my question is there way to make it so that air isnt being sucked though the bov? or would i have to just buy an after market one?

i also tryed this with a stock talon bov but it was the same thing.

please dont bust my chops im still learning about this ok.
for being self taught so far about mechanics and doing good till now is pretty good kay.

[sr20s14zenki]

See if you can tighten the spring in the bov, should be an adjustment screw. If you cant, you will need to get one that seals properly, hks SSQV or somethng,

[tsuga]

is the screw usually in a visable area?

[sr20s14zenki]

its usually on the side opposite of the air discharge side. what kinda bov is it?

[tsuga]

well its stock from a 89 probe gt and a the other is from a talon

[sr20s14zenki]

both of them are made to be plumbed into recirc, being factory bovs. i think thers a trick to make a talon bov work atmospheric, but im not sure. Get an aftermarket blowoff valve, Greddy RS, HKS ssqv, BLITZ, etc...NO KNOCKOFFS

[ercchry]

i thought a recirc was completely different from a bov? and evan come compression test my motor! haha.... please?

[sr20s14zenki]

not necissarily. They operate on the same principal,but from the factory, they are of course not going to pay attention to the sealing abilities of the valve if they dont have to, thats why they leak atmospheric.

[tsuga]

ah sweet thanks for the info

[Supa Dexta]

The reason for it is, that when running a maf set up, you measure the amount of air entering the intake. It then goes thru the turbo, piping, intercooler, more piping, to where the bov is, if there needs to be air released, it needs to be put back into the system (after the maf) because it's already air thats accounted for and the ecu is expecting it and has fuel ready for it.

If your metering system is after the bov there is no worry of this, because it doesn't get measured until after the bov, and the air before that point can do whatever it wants.

When running a system that is supposed to be recirc'd, releasing to atmosphere, you can get problems in your air/fuel, rich or lean conditions, stuttering, stalling, hesitation.. etc.. Some people ignore it (ricers who want a loud bov) and some people just don't experience the trouble as much as others.. At the end of the day the system is designed to be used with recirc'd air...

[Annoyingrob]

Easy fix.

Put it back the way it was. It's recirculated for a reason.

[Eleanor]

Originally posted by Annoyingrob
Easy fix.

Put it back the way it was. It's recirculated for a reason.

Not worth your car running rich everytime you let off the throttle for the PSH sound.

[teggypimp95]

This is the same for my VW. You have what is called a diverter valve not a blow off valve. The computer needs to measure the air being put back into the intake pipe. If your just releasing it your are going to have fuel to air ratio problems and probably throw some codes. Your car will not run as good.

There are aftermarket diverter valves if your looking for sound or just a better one. I upgraded mine on my GTI.

[teggypimp95]

Originally posted by Eleanor


Not worth your car running rich everytime you let off the throttle for the PSH sound.

True, but if you have a short ram or CAI you should be able to hear the psss if the factory bov if thats what your going for.

[2.0turbo]

Originally posted by Supa Dexta
The reason for it is, that when running a maf set up, you measure the amount of air entering the intake. It then goes thru the turbo, piping, intercooler, more piping, to where the bov is, if there needs to be air released, it needs to be put back into the system (after the maf) because it's already air thats accounted for and the ecu is expecting it and has fuel ready for it.

If your metering system is after the bov there is no worry of this, because it doesn't get measured until after the bov, and the air before that point can do whatever it wants.

When running a system that is supposed to be recirc'd, releasing to atmosphere, you can get problems in your air/fuel, rich or lean conditions, stuttering, stalling, hesitation.. etc.. Some people ignore it (ricers who want a loud bov) and some people just don't experience the trouble as much as others.. At the end of the day the system is designed to be used with recirc'd air...

Although this is true, it won't make a difference at idle, only when you let the rpms drop like when you put it into nuetal from a cruising speed. Then it will mostlikely stall because it will be rich. If its leaking at idle, then there is probably something wrong with the bov anyways, so that should be addressed first.

Then when you fix it and put it back together, put it back the way it was supposed to be unless you have some kind of aftermarket air/fuel controller or you'll always have problems like this.

[Annoyingrob]

Originally posted by 2.0turbo


Although this is true, it won't make a difference at idle, only when you let the rpms drop like when you put it into nuetal from a cruising speed. Then it will mostlikely stall because it will be rich. If its leaking at idle, then there is probably something wrong with the bov anyways, so that should be addressed first.

Then when you fix it and put it back together, put it back the way it was supposed to be unless you have some kind of aftermarket air/fuel controller or you'll always have problems like this.

Not true. There are several BOVs that will remain open when a vacuum source is held on them.

Think cheap OEM.

[sr20s14zenki]

Not ALL cars will run terrible when you vent to atmosphere, depends how they are set up. Sr20det uses maf, measures the air BEFORE the turbo inlet, but still ive never had mine give me problems when i VTA.....

[2.0turbo]

Originally posted by Annoyingrob

Not true. There are several BOVs that will remain open when a vacuum source is held on them.

Think cheap OEM.

Oh. I guess so. Although I know that dsm bov's don't remain open at idle so I was thinking of that one. I don' t know about the mazda/ford ones.