Anyone know the Fuel Pressure Specs for the 03-04 Cobras. I'm looking for Pressure at Idle and then Average Load Pressure under hard accell.
Thanks
Thanks
ecal533
03 cobra idle FP
I know the FP on mine sitting at idle is 42lbs, thats with an aftermarket autometer electric gauge.
I know the FP on mine sitting at idle is 42lbs, thats with an aftermarket autometer electric gauge.
The target pressure drop across your injectors is 39 PSI. The pressure drop across the injectors is the rail pressure minus the manifold pressure.
If you are idling at about 20" of Hg of vacuum, that is about -10 PSI of pressure in the manifold. With -10 PSI in the manifold and 39 PSI across the injectors, You should see about 29 PSI of absolute pressure at the fuel rail.
Pulling the vacuum line off the FRPS tells the PCM that the manifold vacuum is 0 "Hg=0 PSI, so your absolute rail pressure should go to 39 PSI because the PCM will tell the fuel pump to crank it up. That also gives you an actual pressure drop across the injectors of 49 PSI, so your fuel delivery will go way up while the vacuum line is off.
Even at WOT, the PCM tries to keep the fuel pressure across the injectors at 39 PSI. It uses data from the FRPS to raise the voltage to the fuel pump just enough to keep it there. So as you go into boost, the absolute fuel pressure should go up to 39 PSI over your boost. So at 10 PSI of boost, for example, you should see an absolute fuel pressure of 10 + 39 = 49 PSI.
If you are idling at about 20" of Hg of vacuum, that is about -10 PSI of pressure in the manifold. With -10 PSI in the manifold and 39 PSI across the injectors, You should see about 29 PSI of absolute pressure at the fuel rail.
Pulling the vacuum line off the FRPS tells the PCM that the manifold vacuum is 0 "Hg=0 PSI, so your absolute rail pressure should go to 39 PSI because the PCM will tell the fuel pump to crank it up. That also gives you an actual pressure drop across the injectors of 49 PSI, so your fuel delivery will go way up while the vacuum line is off.
Even at WOT, the PCM tries to keep the fuel pressure across the injectors at 39 PSI. It uses data from the FRPS to raise the voltage to the fuel pump just enough to keep it there. So as you go into boost, the absolute fuel pressure should go up to 39 PSI over your boost. So at 10 PSI of boost, for example, you should see an absolute fuel pressure of 10 + 39 = 49 PSI.
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