Lorax

I had my vitesse MAF installed last week and all was well, but I added SFR intercooler 2.5"pipes with greddy type RS BOV and now dont get above about 12-13 PSI.

Its a very slow spool.

I dont have the hose to recirculate the BOV at the moment, So its venting to the atmosphere. I get a strange chattering of air coming out between shifts. Thats the only way I can explain it, its not a smooth "psst" like it should be.

The stock end tank outlets are 2.25 inch, and my IC pipes are 2.5 inch... I have Tighened down the 2.5 inch coupler onto the 2.25 inch hole and it looks like its succesfull. I have no choice because I dont have any reducers sitting around at the moment... I dont think they are leaking but its possible that that is the problem.

That just doesnt explain the "pressure chatter" though....

Im a little rushed to get the car running right at the moment as my DD has just been totalled...

schadenfreude

One is causing the other, I think. Your blow off valve will only open at a certain boost, underneath that you'll still get a pressure wave going backwards through the compressor. This leads to compressor surge which can give the chatter noise as the wings of the compressor oscillate between 'gripping' the air and slipping (forget the correct word, but you know what I mean). A bit of surge is normal if you back off the throttle when not at full boost.

I'm guessing some sort of boost/vac leak is causing the low boost / slow spool problem?

Lorax

Yes... That makes sense.... But why The chatter suddenly? I tested it now with the stock BOV and had the same result whie circulating to the atmoshere.

ehall

vac. leak.

fast951

Ryan, Double and triple check for vacuum leaks. Use a good factory BOV till you figure out the problem.

xsboost90

BOV opens when you let off the gas- make sure its not on backwards- not all flow the same direction.

reno808

What is the spring rate on the BOV

Ski

this is so common when going from AFM to MAF, the old BOVs just can't take it. Same thing happened to Rhobs car, blew it, "psst psst psst psst" sound - classic signs it's toast.

reno808

SKi but he is using greddy type RS BOV.

Ski

Yeah, Rhob bought some super BOV and he toasted it within a 1000 miles. Got a LR unit and life has been good for 3k miles @ 17 psi on his car. Almost every "chatter" that's been discussed has been BOV trouble - may not be but I think it's a good place to start, maybe it is a vac leak or just a simple plumbing issue.

TRP951

I thought there was something going around that those greddy vavles leak?

Cory9584

maybe you need to turn up the boost since you now have more area to pressurize with the larger pipes?

Lorax

I have turned the MBC up with no result. It seems like something is leaking once it gets enough pressure... Ging to check IC couplers once more.

The chattering is the same with the good stock BOV as well as the greddy BOV.

Time to triple check everything....

DDP

At idle what Vac reading do you have?

reno808

Good question