I bought a used 2003 evo VIII, as far as I know it's got a stock turbo, wastegate, etc... except a BOV. After reading the modding your evo for $100 at a time, I bought a manual boost controller.

I took it for a drive today (without the boost controller) so I could see my max boost so I make sure not to exceed it without a tune. I was surprised to see it reached about 24, 25. My understanding was stock was a bit lower than this. Now I'm wondering if there was prior tuning to turn up the boost on this thing and I' questioning installing the MBC.

Are boost readings that high normal? Should I go ahead and install the MBC anyways?

 

Look at the driver side frame right under the air filter. Do you see stock boost solenoid or aftermarket?

 

^ its a gold lookin thing, also stock should be around 19lbs.

 

It does appear to be the stock solenoid, and my understanding was stock was around 19. Hence why I was surprised. Could anything else cause it to go that high? Maybe just a crappy boost gauge... I'll be installing a new prosport premium soon, I wonder if it will still hit that high?

 

yeah mins ran 19psi peak and 15ish by redline when it was stock. is it possible you have a tune already?

 

Save for the wide band first brother.this should be your first gauge,boost gauges are inexpensive you can buy them for cheap.having wide band at least you'll see if you running safe.

 

It came with the boost gauge, and I had a pro sport so I tossed it in. I have been wanting a wide band.

This may be a dumb question- but since I am running test pipes and the rear o2 is basically useless- can I save the welding of the bung for the wideband by just putting it in the existing 02 spot?

That's the only reason I haven't done it yet is that pain of finding someone to weld it.

 

The rear o2 is too far back to be a good place for a wideband. Any muffler shop should be able to weld it for you.

 

I used the rear bung on my first evo for my WB. You can disable the ecu from looking for a rear o2 and use the bung and not get a CEL

 

were you getting pretty accurate readings that far back?

 

Just take a look at what the mfg of your wideband recommends and follow that.

 

From what I remember reading, you're supposed to have the bung for your wide band with 14-16 inches of the turbo. Mines in the middle of my downpipe basically.

 

What BOV is on there?

 

Not trying to sound like a noob or anything but how exactly does a wideband help you besides reading the air to fuel?.. how would u know if there's something wrong ?

 

Boost control devices, be it the stock factory ECU/BCS system or a MBC, cannot lower the peak boost level below the actuator's spring pressure. The previous owner for example may have had a MBC on there set to control peak boost to, or above 27# and he may have adjusted WG spring pressure(preload) via the actuator rod to 25-26#. Or the turbo may be retrofitted with a heavy duty aftermarket actuator such as an FP 25# unit.

So, maybe when he went to sell the car he removed the MBC but neglected to readjust the actuator spring pressure down to a level below the MHI factory set 18-20# peak level.