I have replaced fuel pump, filter, all injectors and plugs on a 3.1fi gm. Still loading up at idle and slow speeds but takes off like a scalded dog when I hit the gas. Only thing I havent replaced is coils and coil pack and fuel module. Scracthing my head.
Hmmmm..... 'Loading up'....... That description might mean different things to different people. Perhaps a better description would help. What exactly is the engine doing? Stumbling at idle? Dying at idle? Something to do with the idle circuit in the F.I., I would assume.....
Acts like its loading up p with fuel, its starts stumbling and sometimes stalls. If you start off slow it sputters. Once you punch it, it smooths back out until you hit another red light or stop sign etc.etc. funny thing is when the motor is cold sometimes it doesnt do it until the motor warms up.
The obvious places to start are the engine coolant temp (ECT) & air charge temp (ACT) sensors, the O2 sensor, manifold absolute pressure sensor (MAP) and if it happens to have one, a mass airflow (MAF) sensor. Also check that the vacuum line to the fuel pressure regulator on the fuel rail is good, as this can affect not only the pressure in the rail at idle it also is directly connected to the MAP sensor and can affect it.
