2 bar map sensor Options

[jesterwr217]

ok im currently using check valves and im wondering what i have to do to put a 2 bar map sensor on just take out the map sensor and put the new one in and replace the check valves with regular vac hosing? and i have an safc 2 what do i need to change on it so my ecu isnt all screwed up? and if anyone has a link to somewhere i can buy one that would be great

[NuclearHappineS]

>>with that setup your telling the SAFC that you have 4 airflow signals coming in, and 8 going out?!?!

This is called hte SAFC hack, it's a horrible way to tune a car.

What it does is tell the SAFC that you have 1 bar hooked up, and to lie to teh ecu and tell it that you have 2 bar hooked dup

so if your 1bar is reading 5 volts, and your corrections are 0% then the SAFC will report half that voltage (2.5volts) to the ecu... this does allow you to idle doulbe the size injectors, but it has a major shortcoming which is...

once you go above 0psi ... the map sensor no longer knows anything... it will read 5 volts weather you run 0 psi or 20psi. The SAFC will see this 5 votls and report it to the ECU as 2.5 volts, you will never hit fuel cut this way, but this way you will get the same amount of fuel being dumped in for 0psi as you do for 10psi.

So what you are forced to do with this setup is take your car to a dyno and dyno it and tune it at 10psi.

What happens when you are running 3psi ?
well you are running very rich because you have 10psi worth of fuel (so your boost transition and throttle response will suck

What happens when you run 12psi on a cold night where boost bumps up just a bit?
well you will run lean because you are missing 2psi worth of fuel and can possibly blow the motor.

This setup is cheap, and it may work, but in the end it is a hack, and it leaves your ECU totally blind

A 2 bar map sensor will give you the same result, except the ECU will see boost, you will get boost dependant fueling, and if anythign fails with your boost controller you will still have a fuel cut somewhere around 12psi to save your motor...