I have a mbc on my car and I want to know if turning the turbo down will increase gas mileage. If it does, theres no need to have it turned up all the time.

 

You're only boosting ~10psi stock. Lowering your boost to a level that would make a measurable difference in your mpg would only put you in limp mode since you have a map sensor. If your actual/requested boost is off by much your ecu thinks something is wrong. Just light foot it. There is no reason to use a mbc with a k03 unless you're trying to control spikes. You will get better mpg with using just the n75 and no mbc.

 

why dont just stay out the boost!

 

Proof on that one? Thats like saying you will get better mpg with an ebc than mbc. They are all boost controllers. Using one over the other has 0 to do with mpg.

OP, if you are concerned about mpg, just part throttle it to 3k and shift, this will keep you out of boost (or only boost 3-5psi max) and you will get better mpg.

 

Using an electronic/stock boost controler results in a more gradual signal to the wastegate, which means you see peak boost less often, which means fuel maping responds accordingly, which affects mpg. When you use a mechanical mbc, most times holding a steady 5 psi is almost impossible for normal cruising acceleration. Boost is more on/off. Your actual boost is almost always higher than requested by the ecu, which is why DBW/map engines sometimes do not take well to a mbc. Even with a gated/bleeder type this is the case. I have vag com logs of my actual/requested boost being way off with the use of a mbc. You've seen these yourself. More boost than necessary, or requested by throttle ange means more fuel correction. Tell me that doesn't affect mpg.

 

this is what I do....

 

with a mbc and 2.0, i can still more than manage to go from 0-60 w/o ever seeing more than 1-2psi with a ko3. Keep in mind we are comparing auto vs man here.

 

I know it's possible to stay out of the boost, yet accelerate at the same time. Even a 1.8T w/auto can do it w/out being in tip mode. Not very easily, but like I said, light foot it as best as possible and using just the n75 will keep your boost more settled and gradual for part/mid throttle/daily driving.