91 vette
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: 91 vette (6spd)
It varies, depending on driving style. Don't go WOT often and drive at varying speeds and loads.
The Block Learn Memory (BLM) has 15 cells that contain fuel correction data. Which cell is referenced depends on engine conditions. After going into closed loop the ECM will update the fuel trim data in each cell that it uses.
When you reset the ECM these BLM cells are reset to the quiencent value of 128. Then as you drive around and the ECM references each cell it will adjust the data based on current O2 sensor readings.
FYI, whenever you go to WOT the ECM immediately sets the BLM cell number to 15 which always has the neutral value of 128 and the Integrator (another fuel trim data storage) value to 128. This is why we can trim fuel at WOT with an AFPR...the ECM is reading the O2 sensor but ignoring the data under this condition.
The Block Learn Memory (BLM) has 15 cells that contain fuel correction data. Which cell is referenced depends on engine conditions. After going into closed loop the ECM will update the fuel trim data in each cell that it uses.
When you reset the ECM these BLM cells are reset to the quiencent value of 128. Then as you drive around and the ECM references each cell it will adjust the data based on current O2 sensor readings.
FYI, whenever you go to WOT the ECM immediately sets the BLM cell number to 15 which always has the neutral value of 128 and the Integrator (another fuel trim data storage) value to 128. This is why we can trim fuel at WOT with an AFPR...the ECM is reading the O2 sensor but ignoring the data under this condition.
