UPDATED- AFM induced fuel cut

furpo

New member
with an ignition advace plot using a scope. the same way you would do a plot for a car with a dizzy.

roger
 

gpmarzan

New member
so isnt putting a mbc to the turbo pressure sensor same thing as disconnecting the hose? like Gary said. Whats the point on putting a mbc then if you can just remove the vac hose?
 

RIalltrac

Active member
because if you set up your boost controller for say 16 psi, when the boost hits 16psi its going to open the boost controller up and allow 16 psi worth or pressure to hit the sensor, and in turn initiating fuel cut. You keep the fail safe of FC, which is something I definately want to keep. for safety reasons.
 

gpmarzan

New member
RIalltrac":17pox9z5 said:
because if you set up your boost controller for say 16 psi, when the boost hits 16psi its going to open the boost controller up and allow 16 psi worth or pressure to hit the sensor, and in turn initiating fuel cut. You keep the fail safe of FC, which is something I definately want to keep. for safety reasons.
but if you set the boost controller up to 16psi for the sensor, the sensor is still programed to hit fuel cut at 12psi, so when you pass 12psi, you will hit fuel cut way before you hit 16psi on the boost controller. the way to use the mbc with the sensor is to set it to a lower psi setting, correct? so that means you will set the mbc to less than 12psi while boosting to whatever you set your other boost controller to, which basically means no fuel cut-same as disconnecting the vac hose. am i having brain farts? let me know if i am. :twisted:

edit: i dont know if we're on the same page, chris, but your plan is to use a mbc as a fcd right? i think a mbc will eliminate the fuel cut entirely for the reaon i stated above.
 

RIalltrac

Active member
okay let me clear my head, from what I understand a mbc will allow you to build boost to a certain point, once that point is hit the mechanism inside the mbc will open an allow pressure through to your waste gate actuator thereby opening the waste gate and limiting boost to what ever it is you have it set at. Now if you set an mbc up to whatever it is you want fuel cut at, for me I'll use 16 psi, and place it before the pressure sensor but after the manifold. When the manifold reads 16 psi, the mbc will allow pressure through to the pressure sensor, and since the pressure sensor kicks on at 10-12 psi 16 psi will be more than enough to kick it into Fuel cut mode. Now just correct me if I'm wrong as to how an mbc works, because if it works the way I think it does, the mbc could very well act as an fcd. I would think turning the setting down would just allow you to hit fuel cut at whatever the factory setting is, because you'd be allowing any pressure over what you have it set at through the mbc, example you set it at 5 psi anything over 5 psi is going to get read at the pressure sensor.
 

gpmarzan

New member
ok i got it down now. i thought it over again and yea youre right. :doh: thinking of having 2 mbc got me all confused.
 

Rallly

New member
91 Celica AllTrac oem turbo

After disconnecting the rubber hose(blocking it with a bolt) that goes to the turbo pressure sensor, my fuel cut has been gone, YAY:)
With the nipple capped on the sensor side my oem boost gauge is always showing MAX boost in my gauge cluster.

With the nipple NOT capped, oem boost gauge goes up and stays at 1/4.

Car seems fine both ways but I wonder if with it capped showing full boost on cluster if this will alter what the ecu does with fueling?

Any ideas?
 
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