Most of the problem is that the stock valve leaks at idle. An aftermarket valve that is made as a blow off type should work ok, it'll just run rich during a shift, and you could argue that it's good to do that.
That's assuming that you're pushing boost at all times, which most likely, in daily driving, you're not. Anytime the BOV senses vacuum, it's open, and that's when it's leaking, as well as at idle.
If you run mostly WOT, then yeah, you'd only leak during shifts.
I did this today. Pulled the recir-valve off the nipple on the intake plumbing. WOW, that sounds really, really good. I didn't feel any difference in performance though??? But you guys say it is detrimental to performance, will driving like this hurt anything? Could it be possible to keep the sound and make it run at its best (without buying an actual BOW)?
Thanks,
Mark
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
Yeah, you're gonna be running real real rich, and thats never real good for the plugs, injectiors, or your cat. Smell the exhaust (or watch it billow out of the tailpipe) and you'll know something's up.
As for the sound, place a small microphone inside the re-circ hose, and hook it up to the AUX IN of your stereo head unit. You'd even have volume control over your blow-off, not to mention the EQ and DSP possibilities! A little reverb might just be what the BOV sound needed.
I couldn't see any black smoke out of the exhaust. Does this car rely so much on the MAF? Wouldn't the O2 sensor sense the rich mixture and so the ECU would compensate? When the recirc-valves are vented to atmosphere will it only momentarily run rich during a shift or when easing up on the throttle? Or will it run rich all the time? The difference (between venting to intake and atmosphere) I noticed, was a small loping idle when the engine was cold, thats about it. I don't mean to be skepticle about your knowlege, I'm just curious how I could make this work.
Mark,
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
Well I tryed doing what the article said and........... It worked so far, my idle is just right and you can hear the BOV. I am going to see if I can adjust it to see if it get's lowder with out hurting the Idle. All in all the cost of it was not too much but compared to an aftermarket BOV it is much, much cheeper........ If you all want I can post some pics but I will need someone to host.
How is it both a standard recirculating valve and an atmospheric valve? What's special about APS' BOV that would make it not upset a MAF-based fueling system?
My brother wants me to make a circuit with a loudspeaker under the trunk that reads off the manifold pressure sensor and makes a loud "Pssshhht" sound whenever the pressure drops rapidly from more than 5psi to less than -5psi.
Think there's a market for "electronic blowoff valves?" :)
Could you do me a favor and watch your gas milage for a tank or two and get back to us? It seems to me that, where the Autospeed rig would have less effect of bleed-off during idle, any "pssssht" that you hear is still MAF-measured air not being used by the engine, but all along being compensated for by fuel. I really want to do this, but I can't logically figure out how this would work.