calfroper_06

What psi should i be getting at idle on a 01 gt. IM getting 28 psi and 31ish when i bump the gas

cliffyk

If you are reading the rail pressure directly¹ then that's where it should be. The returnless system holds the rail pressure at 39.0psi, plus the negative pressure (vacuum) in the intake tract, so as to maintain a 39.0psi pressure differential across the injector. This keeps the injector flow rate consistent regardless of intake manifold vacuum.

At idle there will be 18.0inHg to 22.0inHg vacuum in the intake, that's -8.8psi to -10.8psi; let's say -10.0psi for sake of argument.

39.0psi + (-10.0psi) = 29.0psi, and most gauges are only going to be accurate to +/- 1.0psi at best anyway...

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¹ - If you read the generic fuel pressue PID (0x010A) then the value will be the pressure differential across the injectors. It should be 50.0psi KOEO, ands 39.0psi at hot idle and cruising...