No Boost

[Siestarider]

Car ran fine Tuesday track day, Wed am no boost. No codes. Runs fine, just no boost. WG closed with nearly full tension on EFR WG actuator. AP shows plenty of vacuum at idle, I can get it to show me maybe .5 lbs of boost at most. Whirring noise when I try to throttle into boost. I assume that is compressor.

Tightened all the hose clamps. Tried air pressure on compressor outlet, all I can hear is leak back through compressor to air intake. Any suggestions appreciated, I am about out of diagnostic inspirations.

 

[Superfly Snook]

Tightened all the hose clamps.

Did you go under and check the IC charge pipes also? I had one come loose once and got almost no boost as a result. Didn't get a code either. Was easy to feel it was loose flopping around under the car when I pulled off the road but getting a 7mm socket on it to attach and tighten it back on was a whole nuther issue since I was in the middle of a road trip.

 

[92FOX]

Also if you have a symposer delete or plug look at that to make sure all is well. I "made" one, it lasted 100 miles and popped off under boost, and my car was instantly a dog. I'm no turbo veteran, and don't know your upgrades so take what I say with a grain of salt.

 

[Sekred]

Bypass valve stuck open?.

 

[Siestarider]

Yep, checked all clamps. Pulled symposer off and pressure tested it too.

Bypass valve? That sounds promising, particularly as I do not know what it is?

 

[Sekred]

It is located on the compressor housing of the turbo and vents boost back to the inlet of the turbo when you close the throttle as you shift gear. It causes the whose noise. I am sure you know what it is, most commonly referred too as a blow off valve. It is electrically operated on the ST, it is basically just a solenoid that is opened and close by a signal from the ECU.

 

[Siestarider]

It is located on the compressor housing of the turbo and vents boost back to the inlet of the turbo when you close the throttle as you shift gear. It causes the whose noise. I am sure you know what it is, most commonly referred too as a blow off valve. It is electrically operated on the ST, it is basically just a solenoid that is opened and close by a signal from the ECU.

Sounds like a promising suspect, I am so happy I left the heat shield off while tuning, should be able to get at it from underneath. I will do a little research to make sure I understand its operation and report back. Thanks Sekred.

 

[frankiefiesta]

Yep, checked all clamps. Pulled symposer off and pressure tested it too.

Bypass valve? That sounds promising, particularly as I do not know what it is?

He means blow off valve it's on the turbo

 

[Siestarider]

He means blow off valve it's on the turbo

I have a spare stock turbo in garage, looked it over, I can see if its stuck open I would have no boost. Also see it probably cannot be removed with turbo on car. No way to tell if its open or closed without removing it.

I will try disconnecting from electric harness, tap on it, hope if stuck open it will close, then check for boost. Thanks gents.

 

[frankiefiesta]

I have a spare stock turbo in garage, looked it over, I can see if its stuck open I would have no boost. Also see it probably cannot be removed with turbo on car. No way to tell if its open or closed without removing it.

I will try disconnecting from electric harness, tap on it, hope if stuck open it will close, then check for boost. Thanks gents.

It can be removed. I had to remove it to install a boomba BOV spacer on my friends car. It's not an easy spot to access, but with a universal socket and Allen bit, it can be taken on and off

 

[Siestarider]

It can be removed. I had to remove it to install a boomba BOV spacer on my friends car. It's not an easy spot to access, but with a universal socket and Allen bit, it can be taken on and off

Thanks for that tip, I just pulled out a pouch of Allen keys to pull the stock one off the turbo, figured it would not be easy at best, but if it can be done, better than pulling turbo off again.

 

[Racer83L]

I would guess Eco mode but .5 boost is low. I think I get 4 in Eco mode

 

[A7xogg]

He means blow off valve it's on the turbo

you mean divertor valve

 

[Siestarider]

you mean divertor valve

Part has more aliases than a bank robber, no wonder there is confusion over its function. From what I read, its function is to open when throttle snaps shut, to relieve pressure between compressor and throttle body. We have the latest and greatest iteration of a part that has been around a while. Electric operation is faster than former pressure hose operators. But stuck open, behavior should be about what I am seeing. Off to garage to try some things.

 

[Siestarider]

Disconnected electric lead, loosened 2 screws, tapped with a hammer, tightened back up and reconnected electric. No joy. The only part in this switch that could break is the spring, but if it breaks, no boost. So taking it off and inspecting next. Had to buy an Allen socket to get to third screw.

 

[Siestarider]

Update: Diverter valve looks fine, spring works. Swapped out for another one anyway, made no difference.

Still no boost. No codes. I am mystified.

 

[frankiefiesta]

Maybe revert back to stock, see if that helps.

Reinstall Cobb and see what happens

 

[haste]

I have to ask...you didn't change the map to economy mode, did you?

 

[bluestang]

Maybe try and reflash as well

 

[Siestarider]

Already flashed a new tune, no change, and this map has no economy slot. Next try will be back to Cobb OTC tune.