Turbo Compressor Stall - DANGER, DANGER, DANGER!

[gsharrock]

HELP ! [:I]

I've had my 5-speed GT for 40 days and need everyone's help.

The first mod I did to the car was remove the stock air system and install the CAI that AMX1397 sells. Since doing so removes all silencers, I immediately began to hear a fluttering/rattling sound everytime I would back off the gas to shift. Ian and others tell me that this is turbo compressor stall caused by the pressure build-up caused when the throttle plate slams shut, and is damaging to the turbo. So it looks like our friends at DCX didn't do such a good job engineering the turbo system, but did a great job concealing the problem with silencers!!

It was clear to me that the factory surge valve had to go. So I ordered the AGP Turbo kit which includes a blockoff plate for the factory surge valve and a TurboXS Type H BOV.

While I was awaiting its arrival, I installed my TurboXS HPBC boost controller and tweaked it so that I get 15psi at WOT with no spikes, fall-off or P1188 code/CEL. Of course the added boost made the turbo compressor stall even worse.

I removed the factory surge valve and installed the blockoff plate and the BOV over the weekend. I have the BOV running with its lightest spring to make the popoff occur quicker and I'm still getting compressor stall!! [xx(]

Today I'm going to install a larger ID vac line and see if that helps.

Does any one have a similar experience or have any suggestions for me to try?

[RobGT]

I have the stock airbox silencers removed and get the same sound. Anyone else have the same?
With a MBC the sound is more pronounced, but I get the sound without it as well.
Are we sure that this stall is actually what is happening?
Gary perhaps you might post at the SRT forums to get their opinion...

[gsharrock]

Rob,

I posted on SRTForums just now, so we'll see what we hear from over there. I'm 99.99% sure that the sound that we're hearing is compressor stall as the instant the BOV goes off, the sound stops. That would make sense since the pressure is relieved and the compressor is no longer stalled.

I'm starting to get real annoyed with DCX. 'Cause you and I both know if (when) the turbo fails, it won't be covered under warranty because of the mods we've done! [xx(]

[Chipmunk]

Hmmmm, All I Hear when I let of the Gas is my BOV, But I have a HKS SSQV, so I cant really compare. I also still run the stock Bypass valve as well. I was planning on ordering the BOP this week from agpturbo.

Matt

[gsharrock]

Matt - where did you connect your line from the HKS BOV?

[Gear_Head]

I currently use the HKS ssbov. It is installed in front of the throttle body. (between the throttle body and the intercooler cold side outlet). I am connecting Vacum from a Tee fitting directly from
the the top of the throttle body (which is also where I get my boost gauge input from). The BOV pops off even if there is only 1 pound boost (according to the gauge)when the throttle body closes off. I am not using the stock surge valve currently. I am pretty sure that this is the way that chipmunk has his set up too, I used his install as the model for mine. I also do not hear any noises when I back off at any boost level only the BOV. The silencers in the original air box and the turbo inlet tube eliminate ANY noise involning the turbocharger (good - bad -or indifferent). That is one of the reasons that I bought the Turbo up AMX1397 intake system. It kind of makes one wonder exactly what the motivation for DC was it install all of those silencers. Was it asthetics or an attempt to hide a design issue. Who the hell knows. I am not suspicious by nature, but even I am beginning to see a conspiracy behind every noise etc that is out of the ordinary. Oh Well Life goes on. [:I]

Alan

[Ian-PT-GT]

Gear head,

It sound like your BOV is conected correctly. It should blow out even with one PSI ater you let go of the throttle. When you see "0" in your gauge it actualy has 14.6 PSI or more in the system. The engine produces a 15-20 in.hg and the turbo needs to spool up to make normal atmosferic pressure that is 14.6 PSI. The factory BOV is rated to 11 PSI Max. To test this,lower the boost to 10 PSI and see if the noise disapears. Like I said in another post: If it is the turbo making those noises it is because it is getting stopped and then lets it spin again creating stress to the Impeller, This can destroy the turbo and other internals.

$0.02

Ian

[RobGT]

Ive had the same noise, completely stock with silencers removed, no boost controller, no gauges, since day one.
Should I be going in for service??

[Ian-PT-GT]

Nope.

It is how it was designed.
You only need to wory if you increase boost.

Ian

[V8BeatR]

The flutter you hear is from the internal BOV. What is happening is fan blades are still turning and this causes the flutter sound. Its what U should expect form an internal BOV