Dangerous Over boosting!
 

Hey guys questions for you all.

I just put a volvo 16T mitsu turbo in my already turbo 1994 1/2 850 as the past turbo seals were gone and blew smoke.


I have a boost gauge hooked up, it used to boost 9.6 > normal with old smoke blowing turbo.

Then a pcv/vacuum line came loose and pressure went to about 6 with new turbo in, and registered and EGR malfunction code.. so it was cleared after the main pcv line that runs under the intake manifold was reconnected and hasn't come up since, However, my boost gauge now registers up to 20-21 pounds of boost!! under hard accel and the volvo vacuum/boost guage goes past the white line. I'm so scared to drive it, i push lightly on my pedal and i can get to 12+lbs of boost and in winter by tires are just spinning.

Would the new turbo be spooling up quicker even though its slightly bigger and when the ecu is looking or used to drawing its regular boost amount now finding an already quite spoooled turbo and the turbo pumping such high pressure in?

Should I do something with my ECU? it doesn't seem to be adapting, and should i get a new later 850 ecu that has a 16T programmed in it?

TECH!? any help, How do I fix this guys?! I don't want to split my block or something. I love my 854.

Thank you sincerly in advance. Merry Christmas/Happy holidays all! :)

Sounds like your Wastegate is not opening. You need to check the wastegate and make sure it can open, then check your vacuum lines. If one of the line is crack, loose, brittle or off the wastegate wont open and you end up with 20+ pounds of boost.

+1

The 16T and the original 15G are not that big of a difference to cause this kind of issue. There has to be an issue with either the wastegate not opening or the BCS is not working. Check the lines running from the turbo to the wastegate. If they look good, bypass the BCS and just run a vacuum line from the turbo to the wastegate and see what boost you get. You should be getting around 6PSI, if you are still getting 20 PSI when it is connected like this, then the wastegate is bad.

Agreed check the vacuum lines. The hood should have the diagram on how they should be hooked up.

Did you have any luck?