The black hose... what is it's function, and what is the function and description of what appears to be a part at the base connection point? Below the hose clamp, with the 2 socket head cap screws showing on it.
And if was sticking sometimes... What would be the symptoms?
I would think that if it was stuck open, loss of boost/power. If sticking closed the overpressure would interfere with the compressor screws when the throttle is closed suddenly... not sure how that would present itself.
Why would you think its sticking? You can remove the elbow, cap the open side on the intake tube and start the engine. If its sticking you should be able to tell. All it does is vent boost into the intake till you get on the throttle, then the plate inside the tube shuts and sends the boost into the motor. Unlikely that its sticking closed but if its sticking open you will start dumping fuel and have no power.
...but if its sticking open you will start dumping fuel and have no power.
That is the symptom to some degree. It will at times under hard acceleration aka a transition from low throttle to way more throttle seem to have little power, and then all of a sudden (I mean instantly and abrupt) bring it on with the power. It is not predictable or repeatable at least by me attempting to make it happen every time. It's like a switch the change is so sudden with the power. Sometimes though it seems to sputter a bit with the on / off power until it's finally all power. It almost seems like something mechanical in nature is causing this, and it's been that way since the blower was installed.
The bypass valve does open at idle (like it should) and I can see it move to close as I open the throttle way up in the garage, So it is working, but I cannot confirm what or when it is doing what it is supposed to do, under actual driving conditions.
One thing that was clear in the Kenne Belle literature that was posted in the link above was to not use a gauge on that small control line to the valve. Mine has a tee and a long run of tubing to the MAP sensor mounted on the firewall. Should the MAP sensor share that vacuum line? Or be hooked up to some other port?
Also, when I hook my hand vacuum pump up to the bypass valve line it will not pull a vacuum on it. A little vacuum, but my hand can't pump the pump fast enough. If I put my finger over the port on the end of the pump it pulls to 15" and holds with one stroke. So I know the hand pump is good.
Ill check tonight but that unused port is where my map sensor is plugged into, I'm 99% positive. In regards to your issue the roe setup does not like to slowly move into boost, ie ease on the gas and expect to start partially boost to max boost. The system likes a smooth yet quick transition into boost.
The way to test this out is put your car in 3rd gear and start at 3k rpm and stomp the gas. If your car accelerates with no jerkiness you are good. If it jerks that plate could be the issue in that its not staying shut or a tune issue.
Basically that plate likes to be fully open or closed, if you try to ease into full throttle too slow you will feel thatplate close and open, jerkiness.
I have my map sensor hooked up to drivers side port. The bypass valve vacuum line is routed straight back in the intake. I have an additional barb fitting on the intake I use for the boost gauge,VEC, and meth switch. Chuck Tator did the original install so I figured it was correct when I did the 2.8L upgrade.
Under vacuum, the valve opens, which is how the pressure equalizes between the intake tubes and blower manifold when off boost, and where the majority of the intake charge is moved through during low load. The blower is still moving air, but usually not at the same rate as required, and this port balances it. Under boost, it is closed, and the bower is feeding the engine.
The port on the tube is for the OEM MAP so that it does not see boost. If you are running a 2-bar, it is capped off, and the 2-bar sensor is connected to the manifold, seeing both vacuum and boost as it should. This is the "big benefit" of 2-bar, there are not two systems reading at different points, and you don't have to try and get two systems that inherently fight and follow each other in sync, which is nearly impossible to do in all conditions.
What you are describing *could* be the result of the bypass remaining open when it should be closed, and then snapping shut- but if the valve tests good in every which way, it is likely an error in one of the tuning tables. Transitions are one of the most difficult areas to tune, and also where the vast majority of tuners get lost. The Viper PCM is a good bit different than standalone PCM's with how it functions. It might be worth trying someone else's valve and see if it continues.
Dan Lesser @ VSP
Last edited by Final GTS; February 23rd, 2013 at 06:04 PM.
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