CyCloNe!

Hey guys I am currently having an issue with boost, sometimes when it hits 1.2bar on the factory gauge it will surge and won't it boost and act very rough. I noticed on the j-boot there's a tear in the nipple right where the bypass valve connects. It's a rather large, basically the nipple is halfway off... I was wondering if that would most likely be the main cause since the bypass valve probably isn't getting enough air to open.

Also I was wondering if it's possible to delete the bypass valve? and if so what can I expect as far in changes in driving?

Thanks for the assistance.

CDH-CTT

The Factory gauge is WAAAAAAAAAAYYYYYYY off My stock gauge pegs out and my after market reads 17psi
Get an after market (autometer) or another brand gauge to make sure how much boost you are really running.....if there is a rip/tear in the J-boot replaced it....you dont need dirt and other crap getting around your airfilter and wiping out the turbo..... the Bosch Reciruc valves are not really built for high boost, you should look around for a billet DV they can take high boost levels and will not fail.... If you go rid of the Recircu valve you will have some servere drivablity issues, and you will probably blow off the hoses( stock or not) with that much boost... hope this helps....

Carl

Tedro951

I'm betting a new Jboot will fix it. I suppose you could rig up a test where you remove the BV, duct tape the hole (and the tear) and go for a short drive to see, but I wouldn't waste the time. You still need a J boot. Used are out there, new aren't all that expensive. Let us know how it goes.

onspeed

Bypass valve is needed to prevent compressor surge (compressor spinning backwards) by venting the pressured air back to the inlet as opposed to letting it flow back towards the turbo. Or something like that. Point is that driving the car without one is not a good idea.

Tedro951

I'll bite. Why do you want to delete the BV? I'd delete the tired, torn Jboot.

racerxrick

the BV (BOV) on my 951 has been replaced with a quality billet version. I could install one that vents to the atmosphere and goes "sphisssshh" but I'm afraid I'd be ex-communicated...

TurboTommy

yeah, definitely don't delete the BV; very important part of the turbo system, for reasons already mentioned.

The stock boost gauge is pretty much right on the money at those low boost levels; it's only off when you get past 12 to 13 psi or so.
The rough running could very well be because of the hole.
The fact that it's not boosting past 1.2 on the factory gauge is somehow the system is not getting the signal to go into full throttle mode. It could be that the tear in the J-boot is causing it to run lean throwing it into limp mode, or it could be a different issue all together (maybe CV, TPS, KLR)

eniac

Do not bypass the bypass valve. It can cause the center nut on the turbine shaft to spin loose which is catastrophic for a turbo. I had one explode on me by running 35psi with a stock bypass valve. I assume this is similar to what would happen if you ran less boost and no valve. At 35psi, the air could not be vented quick enough. When the throttle body was instantly closed to shift at 6500 engine rpm and 35psi, the resulting air pressure caused a slowing force on the impeller while the main shaft was spinning at 180,000rpm.

The result....well I might as well have stuck a grenade in there.

azmi951

I have a good J boot $50.

ehall

I say ditch the BOV and film it! We LOOOOVVVVE good vids!

Van

That actually sounds right on the money... the stock gauge goes to 2 bar absolute, that's 1 bar boost pressure - which is about 14~ish psi. So I would definitely think it would peg at 17 psi - 3 psi more than the gauge can show.

pettybird

you saw that too, eh?

CPR

CyClone,

I have a good J-Boot. It is the original off my car, which I removed at around 48k miles.

If you want it, come pick it up for $60

CyCloNe!

Yes sir, Ill be at your door buying your jboot and stealing your keys

Willard Bridgham 3

I don't know about others, but I have a calibrated mechanical aftermarket gauge and the stock pressure gauge (boost is pressure) and the stock and the aftermarket are in close agreement.

It is some kind of urban myth that the stock pressure gauge is inaccurate.

Pressure gauge on the dyno agreed with both stock and aftermarket gauges.