So, what exactly is the PCM "learning"?

New PCM in The Truck today. First thing I noticed is it idles better... didn't really expect any difference, because there was no difference between the old PCM working and dead.
I've read where the PCM will now learn my driving habits or somesuch. What does this mean, in practical terms?
jmc
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 07/31/2010 05:37 PM, jmc wrote:

For the first tens of miles, up to about 100 miles, of driving, the engine sensor outputs are recorded. This will be the baseline for the computer to consider your normal requirement of throttle response, shift points, and loads on the drivetrain.
If you baby it, then the system will perform to that level.
If you are very aggressive in your driving during this period, but, you normally are a smooth operator, the vehicle will be more aggressive in it's response, after that aggressive baseline is established.
If you share driving the vehicle with someone at the opposite end of the pendulum then one of you will be a bit unhappy driving it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

IIRC this is not limited to any specific distance or time, but is a moving average. That is, it keeps learning and adjusting all the time.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK..very basic terms.. We just replaced the battery in our 99 Ram.. For the first 5 or 6 starts, it wouldn't idle and stumbled on hard acceleration.. After several short trips, the truck ran and idles as before..
mac
Please remove splinters before emailing
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Maybe your IAC is dirty.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No idea what an IAC is, but after driving the truck a while after replacing the battery, it runs great..
mac
Please remove splinters before emailing
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 11 Aug 2010 23:07:01 -0700, mac davis

Idle Air Controller, FWIW... Controls idle.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Battery died and it went without a battery until the next shopping trip to the States.. about a month..
Put a new one in from Wally-world on their free exchange deal and the truck runs fine now..
mac
Please remove splinters before emailing
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My '99 RAM Van acts exactly the same way whenever the battery is pulled. It refuses to idle and I have to hold the pedal down to keep it from stalling. I let the pedal off gently and goose it when it starts to stutter. After 2 or 3 minutes of this it "re-learns" how to idle and runs fine hot or cold until the next time the battery needs to be disconnected.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.