brrgrr

Hey All-

I posted a while back on boost creep. After checking everything (all hoses and MBC OK) and doing some more observation it looks like I have "Classic" boost creep :

The boost will go up to the set amount on the MBC .... 15 psi, for example, and level out for a second, then it will steadily rise with RPMS to very high levels if you are not careful - (20+ psi) - you can turn the MBC to a lower level but it will still rise with RPM - my LR dual port WG cannot bypass enough exhaust to keep the turbo in check !!!!!

This is due to a combination of several factors:
- Kokeln Stage V turbo , 3" full exhaust, ported head, stg 2 intercooler etc all flow at high RPM
- It's been very cool (35 to 45 degrees) here in nebraska

What are the next steps ?? Porting the WG ? Going to a larger wastegate ?

I just don't want to grenade the motor dusting off one of those pesky WRX STI's.

67King

I am guessing to a degree, here. Is the boost controller you have just a simple turn to adjust unit, with one in and one out? If so, it probably has a checkball and spring in it, and if there is air flowing through that, you are fine. Assuming there is no bypass, the pressure will eventually equalize, and the ball will re-seat. Not an uncommon with a lot of the manual boost controllers. The better way to do it is to pull a T off of the banjo, send one side to the wastegate, and recirculate the other (after the air meter, before the turbo). I made one of my own with abotu $10 worth of hardware store parts, and it worked flawlessly (and with an integrated wastegate, too boot!). Even a variable orifice one will equalize. To get one of those valve things to work, you really have to split the line, and put the metering side on the bypass.

TurboTommy

I got the same problem.
LR dual port; uncontrollable boost creep on a 3.0L.
Had already started a different thread.

toddk911

As discussed in your previous thread, boost creep is only 1-3psi max, not 5.

Cold air will cause 1-3psi. 1-2 in the lower gears and 2-3 in 3rd and 4th.

But once you reset your MBC down some to adjust for the colder air, it should be fine and not continue to rise. If so, it is not the oclder air.

So it sounds like you have a sticking wg, an issue with the dual port or the MBC itself.

In what gear are you running in to set the MBC?

brrgrr

I set boost in 4th gear typically. I ordered a new boost **** and I'll put it in and let everyone know how it goes. If that doesn't work then I'll check into the wastegate over the winter.

brrgrr

Just to complete the thread - a new MBC was installed and it solved the problem - boost is now rock solid all the way to red line. It was shocking how dirty the old MBC was after 8-9 years - filled with soot and debris.