why have i never hit fuel cut in my s5TII at 10+psi? i have no fcd (its sitting on my desk since its useless right now) and i'm just wondering how my stock ECU could not be cutting fuel.

could my stock boost sensor be bad?

 

maybe its chipped? inaccurate boost guage?

 

i was thinking that maybe my EC could just be seeing low voltage from the pressure sensor (kinda like what the fcd does to trick it)

sound possible? is there any way to test it other than watching a multimeter while boosting it?

 

Watch a multimeter while using a mity vac to put pressue in it..

 

what about vacuum, is there a required voltage reading for vacuum as well? or just pressure?

i guess pressure is the more important one here anyways

 

anyone?

 

in the fsm they give you the specs, and then you can graph it out

 

A previous owner may have installed a FCD at the ECU.

 

is there any way i could visibly see the FCD on the ECU? (like if i took the case off)

 

mine was getting low voltages

 

Is the dash boost gauge working at all?

It should be showing what the ECU is getting from the pressure sensor.

 

no i have an NA gauge cluster so no factory boost gauge.

 

To bench test the pressure sensor:
Using an old PC power supply & a VOM.
Turn the boost sensor over with the connector facing up You should have a blank space in the upper left corner.
The blade in the upper right is boost signal, the blade in the lower right is 5v and the blade in the lower left is ground.
The red lines on PC power supply should be at five volts, but check them first.
Take some female blade connectors and attach them to the ground and the 5 volt on the PC power supply then hook them to the boost sensor, then use your multi meter to check the boost signal as you vary the pressure.
It should go down to like .75 under vacuum.
At 8 PSI of pressure it should be somewhere around 3.5 volts.

 

It won't be in the ECU, it'll just be near it. It's no different to mounting it near the pressure sensor; you're just at the other end of the wires. You'd see a small box with 3-4 wires tapped into the ECU loom.