No matter what spring rate you have the wastegate will not open if the boost reference line is disconnected or cut. The spring is designed to open up when 9psi of boost presses against the diaphram. The exhaust pressure will not force open the wastegate therefore it will remain shut unless you clog the turbo up and enough backpressure builds up to force it open. I've logged over 35psi of exhaust back pressure when I was using a small exhaust system and turbine housing and that wasn't enough to force open my wastegate so I would assume it would take a considerable amount of exhaust backpressure to open a wastegate.

No boost reference on wastegate= wastegate will remain closed. That's why ebc's have a fail safe for overboost.

 

This.

Sometimes seeing it can help, just to better understand.

http://youtu.be/PA5T5PnWE-k

 

no idea how mine were opening then when the line was severed, it wasnt seeing more than 14 lbs tho which is what my spring pressure is

 

Thanks Jeff, I understand what your saying, and you explained it better then I... Bottom line, the gate on that side wasn't opening, and the other side was opening up earlier since more pressure was being built by the one turbo then the one working properly.

 

are you sure it wasn't the top port boost source that was damaged? Losing the top port boost reference would cause the wastegate to revert to spring pressure only.

On the dyno my wastegate was getting so hot I melted through 3 different boost reference lines. I ultimately had to order silicone vac line to handle the heat in that small space. When that happened my car overboosted into my boost cut and almost bucked the car off the dyno. That was a loss of the bottom reference port. Never had an issue with the top port.

 

Looks like its time for Duramax badges for my car....last night I hooked up my shitty SFR catch can and it still smokes like crazy. It was at night so I can't tell if it reduced the amount or not?
It seems to come 10-15 seconds after I let off, and recently I did a fairly long high boost pull then came to a stop shortly after and the smoke just poured out until I got going again?
My catch can goes from the rear of the DS valve cover to can from the check valve to can then from can to one of the turbo intakes....there shouldn't be any issues with routing should there?

 

Do you really need that check valve if it's going to the turbo intake? Maybe it's not working like you expect.

 

I would remove those check valves. I've found that check valves are highly restricted which is what blew out my front crank seal.

Look around other places to see if maybe you are pushing oil out the front or rear crank seal which then could get on exhaust and burn.

The routing sounds good though. I wouldn't think oil would get sucked into that turbo with that configuration and a decent baffled catch can.

 

Sorry it's the PCV valve not an actual check valve that I added....it was late when I wrote that. I might go out again in the daytime and see how bad it is, it might have got better than it was

 

once you get oil in the exhaust it will take weeks for it to finally go away. I've had issues twice now and took almost a month of hard pulls and driving to finally burn off all the oil from the exhaust system.

 

im having similar issue when accelerating. wondering if the crankcase pressure is pushing oil up the turbo return line. i have the driver side vented to atmosphere

 

if you are blowing oil smoke during acceleration you may have oil blowing past your oil seals.

 

Turbo is ball bearing. Still spools and oil return line is clear