nightman06

iTrader: (1)

TT setup with external waste gates. Running an AEM Tru-boost with bottom source plumbed to the intake manifold. When I'm at highway speed with a solid 11 in of vacuum I can hear the driver's side (not sure if pass is doing it, too far away) pulsing rhythmically and the AFR gauge is verifying it by going lean each time it pulses. The AFR is mounted on that side, 18" downstream of the turbine, past where the waste gate dumps back into the stream. I can feel the car settle/lag as well.
I am fully aware of the pos/negs of manifold plumbing, but theoretically, shouldn't the constant vacuum be holding the waste gate closed? I have no boost spiking and a smooth boost curve so I don't think there are any issues with the diaphragm. Thanks guys.

gtfoxy

Check the diaghram & mounting hardware as something may have losened up if it didnt do it originally.

Could also be the spring getting weak.

How much over spring regualted pressure are you running?

nightman06

iTrader: (1)

This isn't a new issue, the entire build is still new so Im picking up sounds and noticing things each time I drive it. The springs are brand new as well as the diaphragm, not so say the diaphragm could've picked up a leak, but it doesn't seem to be showing any other common problems associated with that. And my original question still stands, shouldn't it be pulled shut via vacuum in its current configuration? The spring wouldn't be opening with my engine in a state of 11 in of vacuum....would it? And this is a rhythmic pulsing, not a constant state of partial opening. It is literally a perfect pattern almost like a duty cycle (without trying to lead anyone down the wrong path).

gtfoxy

How do you have the waste gates facing?

Obvious solution is to pipe them into the exhaust. No more O2 error.

If the spring & vacuum isn't enough to hold the gate shut then you probably need a stiffer spring, or try shimming it.

stevieturbo

There is no possible way at light cruise with no boost available that you're wastegates should be opening other than a major fault with the gate itself.

And unless your wideband sensor is located somewhere strange, the w/g opening should not impact the widebands readings

A schematic of exactly how you have it all configured would be helpful or worst case some photos.

coltboostin

Correct.

stevieturbo

Only thing I'll add there....is if it is not configured as he actually describes it...

ie intake vac is connected to the top chamber ( and not bottom chamber as he describes ), then in theory this could pull the gate open.

But again I'd never use intake manifold pressure as a reference in the first place for boost control plumbing.

nightman06

iTrader: (1)

So I re-plumbed my waste gate bottom ports directly to the compressor housing and yes, the top ports are plumbed to the solenoid. I don't seem to be having any more pulsing issues so it was most likely an issue with plumbing them to the intake manifold. Much smoother transition up to max boost now and no spiking.

stevieturbo

Really for a low boost scenario, there isnt really any reason to connect to anything other than the bottom chamber.

And the "bottom" chamber is the one closest to the mounting flange.

ie so it's always relying on boost pressure to blow it open, and spring keeping it shut.

You only need to start other connection methods when you need more boost than that can offer.

As for whether you reference to one compressor, both, use one solenoid or multiple...that turns into a huge topic. Keep it simple ! lol