FAST WB02 accuracy w/low voltage

[JeffB]

more voltage fun! even with a 10AWG ground wire the FAST voltage sensor drops as low as 12.3V during a 10 second dyno pull... my question is, when this happens the AFR goes WAY rich in the logs, but the dyno's horriba shows it staying flat... at the beginning of the pull, when my voltage is being logged at around 13.0V my sensor is much closer to the horriba... so, when the voltage drops does this screw with the FAST's WB02 accuracy?

i know the FAST sensor has to be off somewhat... it is reporting like 9.2:1 AFR but the car is running smooth and there is no black smoke out of the exhaust... the dyno shows 11.0:1... both sensors are installed in the header collectors (FAST on one side, dyno on the other)... any ideas?

 

[Craig Smith]

Voltage will have no impact on how the sensor itself works.

What do you have your injector opening time set to? If I remember correctly I just upgraded your stuff, is this true? Battery voltage will have an impact on how the car runs, and the way we handle this now is different than the units produced a couple years ago or more.

 

[JeffB]

the injector opening time is 1.0ms just like always... you are correct that the box was just upgraded... i was running the original firmware on a box that had been made in 3/12/99 before that... the normal drivability stuff seems greatly improved with the firmware upgrade... but at WOT, the dashboard battery sensor still drops and then the O2 readings go way out of wack... like i said, it almost has to be the sensor because the dyno's wideband is 2.0 points leaner... we just took my buddy's mustang to the same dyno today (just two days after i was there) and his Speedpro O2 reads within 0.1 of the dyno's... but he also shows full voltage...