Is it the external wastegate?

[2021cc8V]

specs: 1.8L 16v t3/t4 turbo, 3" downpipe to full exhaust, tial 38mm wastegate


So my 16vturbo issue is that while i'm driving, the car never enters positive boost.

boost/vac gauge reads at 20-25 at idle....stuck my hand under the dumptube at idle, felt nothing.

while driving, as soon as I give it a lot of throttle, my exhaust sounds like a huge open dump/exhaust leak. while cruising it's just the rear muffler i hear.

I'm only running vac line off compressor outlet to wastegate (sideport)

is my wastegate stuck open? or is it just a bad boost leak?

[elRey]

full boost != closed wastegate.

full boost = controlled boost = wastegate partially open or even fully open for improperly sized wg.

edit: just read this part->

issue is that while i'm driving, the car never enters positive boost.

Are you saying your boost gauge never goes above 0psi?

1) an stuck open wastegate (dumped to atm) should be audible even at idle/cruise.
2) even an open wastegate should net you 2-4psi

Do you hear the turbo (high pitch whine ~2200-3200RPM? Can you check if your turbo wheel spins freely?

[2021cc8V]

Boost never went above 0psi.


when the car is not moving (no load), when I rev the motor I can hear the turbo whine.

either way...gonna check to see if turbo is spinning and i'm gonna pull the wastegate and check that also.

but it's making me really scratch my head.

[zwogti]

the sound is coming from the wastegate dump pipe when boost pressure is applyed to the wastegate valve, find out what spring you have on it and than buy the right size spring for your aplication, also a boost controller can be installed to control boost, assuming you have the right wastegate spring size in there for your aplication.

[2021cc8V]

i had the boost controller add-on for the ms2 ecu and it didn't do squat to the wastegate. gonna pull out the wastegate and find out what's going on.

[2021cc8V]

Took the wastegate off. Looks like the bolts started to loosen up which kinda blew out the gasket.

Dismantled the wastegate. It has a red spring inside. Internals were in good shape.

Replaced the gasket with a metal gasket. Gonna finish up tightening everything up tomorrow afternoon and hopefully (fingers crossed) will see some positive boost.

[2021cc8V]

Put everything back, tightened everything up...went for a ride. same thing.

Not building boost past zero on boost gauge (maybe 1psi or so past zero but it's negligible). I do have a very loud exhaust leak (like before) under load.

Before starting her up, I did check the turbo wheel by hand (on the exhaust side) to see if it would spin freely and it did.

argh

[rweird]

where is your boost gauge hooked up?

[kevinescobar15]

What does your AFR say when you give it gas and it only goes to 0? Cause if you have a boost leak it will go really rich.

[2021cc8V]

boost gauge is connected to a vacuum distribution log which is connected to the intake manifold.

AFR is reading 12-13 when I give it some gas.

[bikertrash]

I'm only running vac line off compressor outlet to wastegate (sideport)


should this be hooked to the intake mani post throttle body?

[2021cc8V]

Okay...some updates...





I tightened up the exhaust connections.
Took it out for a spin....same deal....lots of exhaust leak sounding exhaust under load.
Brought it back up on the ramps. The next day, I fired up the motor and while still cold, started spraying soapy water around all the connections, manifold, etc.

Looks like I have a small leak at the turbocharger t3 flange to exhaust manifold area AND a small leak at a throttlebody coupling. Also physically checked the intake side of the turbocharger and was able to spin the turbine wheel. NO shaftplay nor any binding. Also took the oil restrictor off and just ran the oil feed line to the turbo.

Still...should be able to get positive boost right? nope.


I pulled the vac line from the compressor outlet to the sideport of the external wastegate and plugged up the compressor outlet line.

Went for a spin and lo and behold, car started boosting....up to 5psi.


So I think the wastegate was opening way too early...but why?

[2.slowerr]

Having the same issue!

[GinsterMan98]

That wastegate spring is no good. It should be twice that height. Gate is not staying closed.

[2021cc8V]

I bought a tial Yellow spring. Think its 11psi.

[2.slowerr]

Does your turbo have an internal wastegate that's welded? My weld broke opening the internal and letting all the boost out.

[2021cc8V]

Nope. My turbo exhaust housing is a four bolt flange that has a 3" band flange welded to it.

[TBT-Syncro]

where are you getting your gauge boost signal from?

[2021cc8V]

The gauge boost signal is shared with the fuel pressure regulator and the map signal hose from the ecu (well...it's all tee'd to one hose), which then goes to a vacuum distribution log. The log gets signal from the intake manifold.

[2021cc8V]

finally changed the wastegate spring out. that was a bitch...especially when the wastegate was in the engine bay, under the exhaust manifold, between dowpinpe, wg pipe, drive axle, blah blah blah.

anywho...took it for a spin. I HAVE BOOST! 10psi. Right now running boost reference from compressor pipe to sideport of wg.

Soon I'll play with the ms2 boost control.

So thanks for all the advice, everyone...it was indeed a bad spring!