So I purchased an 05' GTP with 136K miles on it. I noticed someone had at least put Flomasters and a 3.4" pulley on it. The factory aribox was loose. When I went to test drive it it drove fine at normal speeds, but knowing it probably needed plugs and wires I got on it and it spit and sputtered and threw a code (multiple cyl misfire), I used this and some other items to pick it up cheap.
I got it home and replaced the plugs and wires and the car seemed to respond, I didn't really get on it hard. Today I added an intake and took it for a spin. The car ran hard and then a few times it seemed to fall on its face. I ran really hard down the feeder and let off and hit it again and it started to miss, like it was loading up with fuel and fouling the plugs. It took several seconds and a downshift to get it to run again. The car feels like my old Supercoupe would get running too cold a plug or a stuck regulator raising the fuel pressure real high.
I checked the fuel pressure and it was 65psi at idle. Couldn't really rev it since its DBW.. Shutting off the engine only dropped pressure to 60#. This system seems like a return less system so I imagine the fuel pump is controlled variable by PWM.
I should also note it acted the same when the factor od was installed.
Thanks,
Jeff