Boost gauge source....wastegate line??

[GreySpeed]

I've searched and never come up with a definate answer other than "any line off the intake manifold". My boost gauge has never been reading correctly, so I want to swith the source to the wastegate line to get an accurate reading. Is this a good idea, no negative effects. Please help me out here.

 

[peepsalot]

You can tee of the wastegate line. How is the boost gauge not reading correctly?

Does it read only vacuum, and no boost? The only line off the manifold that you can't use is the source that goes to the VICS and VTCS solenoids, becuase this vacuum source actually goes to a separate chamber that is behind a check valve that holds a vacuum. Other sources should work.

 

[GreySpeed]

I'm tee'd off the little U shaped hose but the gauge jumps from 10vac to 5 psi with just pushing the pedal to WOT, and it then increases to 10, then to 14psi. This is all happening under 3000 rpms.

You can tee of the wastegate line. How is the boost gauge not reading correctly?

Does it read only vacuum, and no boost? The only line off the manifold that you can't use is the source that goes to the VICS and VTCS solenoids, becuase this vacuum source actually goes to a separate chamber that is behind a check valve that holds a vacuum. Other sources should work.

 

[peepsalot]

I'm not sure what line you are talking about, but mayb eyour gauge is ******. It's possible to build boost under 3k rpms, but 14 would be pretty high. You don't have a boost controller?

 

[GreySpeed]

I know something is wrong, and it's been reading vac steadily, so no leaks. I wanna try it on a diff. line to see if it works proper. Just making sure the wastegate line is a safe try.

 

[peepsalot]

Really, the only way I can think that a boost gauge would read higher than it should is if the gauge itself was broken. I don't think an improper install could do it. If your gauge actually is fine, then I would be worried that your wastegate is not functioning properly and I would fear for the life of your motor.

Does the gauge read exactly 0 when the car is off?

 

[GreySpeed]

Yes it reads at 0, and the car is definatly not pushing close to 14pounds. I have been hitting fuel cut a lot during the winter, however, it is very cold up north. Could the fuel cut be caused by overboosting? i always assumed it was the coild.

 

[peepsalot]

overboosting can definitely cause fuel cut, and cold will make it worse. How can you be so sure that you aren't really running 14psi? Did you get your car used?

 

[GreySpeed]

Well I know there are no leaks, but I guess I'll have my wastegate spring checked. Any other causes that I should check. Bought it new btw.

 

[GreySpeed]

Oh yeah, and I've had the gauge hooked up for 4 months and it has always read the same. So if infact I am boosting 14psi, the engine is holding up pretty well *Knock on wood*

But the thing is, if I am cruising on the highway in 5th gear at 26-2800rpm, and I put the pedal down halfway, it jumps to 5-10psi. Then, when I push into WOT, the needle jumps straight to 14psi. It does not increase consistently like a normal gauge. That is why I have reason to believe the source is faulty. This also happens in the same senario in second,third and fourth gear.

 

[peepsalot]

are you sure the units are in psi, lol.

 

[orng1]

Sounds like you have a bad gauge, what brand is it? See if you can get it repaired by the manufacturer, I remember auto meter repaired gauges or replaced them (at least the tachs, never sent in a gauge) as long as its not caused by the install. Is it mechanical or electric, I can see if it were elec the contacts for power might be loose and cause the jumping you talk about.

 

[sr240z]

You Also Have To Figure Out What Boost You Want To See..... If You Want To See Turbo Boost Get A Source Close To The Turbo Outlet, If You Want To See Manifold Boost Find A Source On The Intake Manifold.
One Will Show You What Your Turbo Is Pushing And The Other Will Show You What The Engine Is Ingesting. There Are A Few Gauges Out There That Will Show You Both And The Difference Between The Two If Its Important To You.