ECM "Learning"?
Thread Starter
Instructor
Joined: Aug 2006
Posts: 247
Likes: 0
ECM "Learning"?
Hi:
Last night the negative battery cable on my '89 worked loose enough so that the car wouldn't start (everything went dead when I turned the key). So, I quickly got the cable tightened back up and everything came back to life. One thing I did notice is that at idle, the idle speed drops way down, then slowly comes back up to normal. It's done something similar to this before when I have had the battery disconnected, but not so severe. Anyway, I am thinking that this may be part of the ECM "learning" process the service manual talks about when the power is cut off to the ECM. Has anyone experienced anything similar?
Thanks,
/s/ Chris
Last night the negative battery cable on my '89 worked loose enough so that the car wouldn't start (everything went dead when I turned the key). So, I quickly got the cable tightened back up and everything came back to life. One thing I did notice is that at idle, the idle speed drops way down, then slowly comes back up to normal. It's done something similar to this before when I have had the battery disconnected, but not so severe. Anyway, I am thinking that this may be part of the ECM "learning" process the service manual talks about when the power is cut off to the ECM. Has anyone experienced anything similar?
Thanks,
/s/ Chris
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Short answer: Loss of battery power removes NVRAM which stores adaptive strategies. Fuel trim is an adaptive strategy. Drive the car normally and the adaptive data will be restored. OBD 1 maby as little as 10 minutes, OBD II maybe as long as an hour. This is from "Corvette Fuel Injection " by C O Probst. Highly recommended reading BTW.
Thread Starter
Instructor
Joined: Aug 2006
Posts: 247
Likes: 0
Short answer: Loss of battery power removes NVRAM which stores adaptive strategies. Fuel trim is an adaptive strategy. Drive the car normally and the adaptive data will be restored. OBD 1 maby as little as 10 minutes, OBD II maybe as long as an hour. This is from "Corvette Fuel Injection " by C O Probst. Highly recommended reading BTW.
/s/ Chris
