I've got a Buick turbo T with 72 lb injectors, WB O2, that is running well. Charging system is fine at 14.2 avg. measured at the battery or alternator terminal. When it's at idle (825 - 850 RPM) and I turn on most any electrical item (lights/heater fan etc.) the actual A/F goes richer as each item is switched on. My target A/F at idle is 13.5, but it ends up at 10.8 with all accessories on !! The battery voltage on the dashboard in the FAST program shows around .3 volts less than at the battery due to normal losses through the wiring etc. but it doesn't drop much lower than 13.6 with everything on at idle. Why is the A/F going so rich with an electrical load at idle ?
I've read that a voltage drop, at idle can effect larger injectors more than smaller ones, but this much ? The car will still idle at 10.8 A/F but it's a bit rough. Even though the voltage shows 13.6 on my laptop, it still is around 13.9 - 14.2 at the battery when all this is happening. Someone also said somthing about a firmware update that may help, but I don't know ? My ECU says Firmware Rev. GM204C with a date of 1/12/98. I also checked voltage at the back of the ECM terminal M1 (Batt 12v) and at L3 (switched 12v) with the engine off, and it was the exact same as the voltage at the battery.
Anyone have any ideas ? Thanks for any help !
I've read that a voltage drop, at idle can effect larger injectors more than smaller ones, but this much ? The car will still idle at 10.8 A/F but it's a bit rough. Even though the voltage shows 13.6 on my laptop, it still is around 13.9 - 14.2 at the battery when all this is happening. Someone also said somthing about a firmware update that may help, but I don't know ? My ECU says Firmware Rev. GM204C with a date of 1/12/98. I also checked voltage at the back of the ECM terminal M1 (Batt 12v) and at L3 (switched 12v) with the engine off, and it was the exact same as the voltage at the battery.
Anyone have any ideas ? Thanks for any help !