Good morning ,

having trouble keeping up boost.

car is sierra 92 , 4x4 , MSD stage 2 chip closed loop , RS500 cooler , greens , T3 , scorpion exhaust no cat , cone pipercross filter.

- checked the system out with my air compresser to 2 bar no leaks.
- tried to wind the actuator further no luck either ( is a brand new -31 one )
- fuel pressure is spot on 3 bar on idle
- car goes overboost 1,5 bar , stable to 1,2 bar . I should get 1,7 bar stable 1,5 bar.

Only thing I donnot know what is the difference in 2 bar and 3 bar MAP does anyone have the serial numbers for these ? I assume I got a 3 bar
MAP sensor.

Steven

 

A 2 bar sensor can't measure these kinds of boost - max. is 1.1 bar.
So you probably should have a 3-bar map-sensor (ask MSD).

Check voltage from map-sensor with ignition on, engine off.
2.2V is 2-bar, 1.8V is 2.5 bar and 1.5V is a 3-bar map-sensor.

2-bar is aps-02, 2.5 bar is aps-06 and 3-bar is aps-05.

 

2 BAR MAP is standard item, when you go to stage 2 or above you need a 3 BAR MAP sensor, Atmospheric pressure is +1BAR so the 2 BAR can only see +1 BAR positive (Boost) pressure you then have 2 BAR total, whereas a 3 BAR can see +2 BAR boost.

You have a 3BAR map sensor otherwise you would not have the boost you do it would also be dangerous, I would check the actuator it should be a -31 or -34 type, the springs go weak after a while.

Martin

 

Got a APS-05/01 so that should be 3 bar.

Just not sure now there it is a stage 2 and it could be it shoudl be running 18 to 20 PSI 1.2 to 1.4

 

could be your boost gauge is'nt accurate ???

 

Hmmm, checked that also just comparing to my fuel pressure gauge and they are going equal up so ...

hen it runs on idle I got - 0,8 bar pressure coming of throttle -1 bar what I think is correct so it cannot be that far off

Steven