Pretty weird

[2GEEZEY]

So when i down shift i got a really loud backfire... sounds cool but not good.
doesnt this meaning running rich a bit?
(this is with my bov recirculated)

So today, i ran it vented... and no problems what so ever! it doesnt backfire, doesnt stall, hesitate nothing.

What is a better way to go? recirc. and backfire? or vent?

 

[Shadow21]

If you dont want to recirc then go with a maf translator setup with a 3'' GM maf.

 

[2GEEZEY]

i know that, im just saying why is it backfiring when its recirculated and when its vented it doesnt?

 

[idkiliketurbos]

Yeah that is very strange. You would think it would be even more rich when venting at a downshift since the less amount of air.

 

[2GEEZEY]

exactly. my friend is venting his also and no problems? i dont get it. especially when the maf sensor is before the recirc. tube, thats why i dont get why the ecu freaks out on some cars.

 

[idkiliketurbos]

I've tried mine out with venting it and I can deffinatly feel it bog down on me at a shift. Recirculating works so much better for my car. Funny how it can be so much different for people.

 

[2GEEZEY]

yeah i really dont get it.....(jeez these cars are never the same) only difference i know is my bov is wayyy louder.

 

[idkiliketurbos]

I like how my hks ssqv with the recirculation fitting in sounds vented but recirculated its quiet as all hell. It just runs better then so thats the trade off I have I guess. Don't care all that much though about BOV sound.

 

[Blackjet18t]

I'm running a type rs. The throttle response recirc is definately better than vented. It is loud as hell vented, also it doesn't run rich between shifts, but I prefer my throttle response over sound.

 

[bmoha2]

It's vented to atmosphere. It's very loud and I've never had any problems with venting it.

 

[2GEEZEY]

im not venting mine because of sound, it just seems to run better with out backfiring when downshifting.

 

[turboglenn]

i'm not touching the venting part

but for backfiring i would first suspect that the TPS is not going to zero (assuming you let off the gas when you shift) Sop this is letting the injectors spit just a tad of fuel in the cylinders, and when there's too little it actually won't light off, so the fumes build in the exhast over a few engine cycles (mere milliseconds) then where there;s enough built up in the cylinders it lights off and carries the flame into the exhaust where that buildup of fumes lights off and goes boom.

This is the case when a car backfires when you are off the gas coasting about 90% of the time so i'm applying the same cahin of events to your shifts, as for why the venting effects it, I'm stumped on that one unless it is chnging the AFR in the engine during the shft but it's late and i cant think clearly

 

[2GEEZEY]

im going to finish my wideband install and see what its saying

 

[turboglenn]

wideband or not i would still check that the TPS goes to "0" when you let off since that can cause more issues that just a backfire. But a wideband can help diagnose either way