spinall4

Hey members,

I'm completely dumbfounded, for the last 3 days I have tried to get my MBC to regulate 19 psi with NO luck. I installed it according to the AMS instruction, thus I'm using a turbonetics unit. Anyhow it's connected with input from wastegate and bleeds out to the T-fitting that was spliced into the Dumpvalve hose. and all other openings have been cap'd .

question is...

1. thought it was a Defective MBC, but did a stright bypass on the 2 hoses and still at 11psi.

2. Thought it was hook up backwards? reversed the unit. still at 11psi

3. Thought it was the hose being to long for vaccuum, shorten it but still 11psi.

The only thing I havent check yet, is the actual input vaccuum line to the MBC maybe blocked internally?? ? and just not feeding pressure to the MBC input?

I dont' know what else it can be??? since the straight bypass on the 2 hoses tells me it's not the MBC unit it self, so after tomorrows inspection of the actual hose going to the wastegate turns out not being blocked ....then what can be causing this stupid problem of not being able to adjust the boost pressure??

Can someone please help with some suggestions??

Thanks -Tom

EvolvedDSM

iTrader: (3)

https://www.evolutionm.net/features/...machvcorner/30

Hook it up like that^^^^

spinall4

hey Jamie,

I check that diagram out already, thanks tho..

So my question is according to the diagram from Mach V it says that the turbo inlet is suppose to be the in on the MBC?"? or am I just see it wrong, with it bleeding off pressure to the wastegate??

Is my system set up wrong right now??? is it suppose to go from the BOV as the signal line to the out on the wastegate hose???

MYEVOVIII

iTrader: (35)

Try it this way works for all Evo owners in my area. Scan down to like 4th or 5th response and you will see diagram.
https://www.evolutionm.net/forums/sh...all+Silverevo8

EvolvedDSM

iTrader: (3)

The Mach V diagram shows the inlet to the MBC receiving pressure from the turbo outlet. The MBC will bleed off some of this pressure to the atmosphere and allow the rest to go to the wastegate actuator.

The way this is written makes it sound like you have the MBC backwards:

spinall4

Hey jamie,

Yeah I think your right, I might have had it backwards. Now can you clear something up for me...I did the same hook up as what everyone has told me splice a T-into the BOV hose right ? and that goes to the IN port on the MBC and the OUT goes to the wastegate..? now my question is what is supplying the MBC with pressure if the T when spliced into the BOV line will only provide vacuum and not positive pressure? or are you suppose to T it from the manifold straight to the MBC hose and the bleedown on the T goes to the BOV??

EvolvedDSM

iTrader: (3)

If you follow that BOV line all the way back, you'll see that its source is the intake manifold (a boost source as well as a vacuum source). If you T that line, then send the added tube to the IN port on the MBC and the OUT goes to the wastegate actuator. The BOV line itself is "unchanged" (it just shares it's signal with the MBC).

spinall4

Hey Jamie,

Don't you think that the line it self will be charged when it's under boost?? If you look at the AMS install they T-fitted right before the BOV. That's the part I don't understand, why does it work for everyone else but not for me??? So I don't think it should matter where you T the line.?

bishiboy

iTrader: (10)

Check out your BOV. Your problem sounds just like mine when my BOV stuck partially open (Turboxs). Happend to a few other's too.
Use new vacuum lines, the stock ones have the restricter pill.
I don't know about Turbonetics, but the Turboxs HPBC increases boost as you turn the screw counter clockwise.
Double check for leaks.
The BOV line is ok to Tee off. It IS recommended to have an uninterupted source (Not tee'd) to the BOV.
When I install a vacuum distribution block, my MBC seemed more responsive, held boost longer.???

hel_if_ino

iTrader: (2)

the only difference in tapping off your pressure source from the manifold vice the turbo nipple, is the boost controller will regulate 19lbs boost from the manifold, not from the turbo, if you sourced it from the turbo, you would have to turn the controller up due to line losses in the intercooler piping. The source, which is your inlet to the controller, should be from the manifold.. the other should go to the wastegate, just make sure you arent using the original line supplied from the stock boost solenoid, as it has the restrictor in line.

spinall4

alright gang,

The problem has been fixed, got a new Hallman MBC today and installed it and it worked perfectly...so with all that said the problem was internal on the Turbonetics unit. so I don't think I'll ever buy another turbonetics MBC.

Thanks for all your INPUT!!