(1997) I've never found a clear explanation of how the computer learns. Is it based on time engine running, distance driven? And how does this relate to going into closed loop? Once the system enters closed loop is it finished learning? For instance, if changes are made to sensor(s) and the vehicle is test driven, what is proper test drive to assure the computer has finished it's adjustments? Thanks in advance!

 

The controller get information from your inputs, like a temp sensor. The vehicle has many inputs and then takes that data and send out message to the outputs. Like your transmission, and the transmission also has inputs as well. About every 5 to 10 years the system will change. So your truck maybe using a CCD buss system meaning the plus is 2.5volts and neg 2.5volts. Or if you know computers. The bytes would be 10101010101010101010. That what the controller reads with voltage. I hope this helps.

 

Thank you for the response! To be more specific, how does the 2nd gen re-learn? For example, the vehicle receives a new battery and data is lost. What process does the computer go through to establish a new base line?

 

Not all are CCD buss, Say you replace a tps and the new tps is a tad bit higher voltage at idle but still in the acceptable range. After the computer recognizes the full range of the tps it will "learn" it. Closed loop is after all the engine gets up to normal operating temperature then it will go into closed loop. Open loop there are variations of the sensors such as the 02's that need to get up to temp before closed loop. There are slight variations in sensors (still being in acceptable range) so the computer takes all the inputs and slightly adjusts(learn) the output to reach normal operation. Does this make scene?

 

One of the reasons you want to reset the PCM when you change sensors, is specifically so the PCM can re-learn it....

 

Ok, so if I make changes then test drive until I enter closed loop, the computer is done learning, correct? No more base line learning after closed loop. For purposes of diagnosing I don't need to test drive beyond that, right? How would a Dodge Tech check his/her work? Would they simply test drive until closed loop, then return to shop check for codes and call it good?

 

Nope. The computer is constantly learning. Computer goes into close loop as soon as a few conditions are met, chiefly, engine temp over 108 degrees, and O2 sensors reporting 'ready'. As the O2 sensor are heated, they are ready long before the engine comes up to temp. (from a cold start.)

The computer can also learn your driving style..... one of the tricks we used to do at the dealer, for complaints about 'lack of power', would be to reset the PCM, then take the care for a drive, and BEAT on it. The customers were generally happy with the results. Of course, the computer would then re-learn their driving style, and be right back where they started.

 

Great information, thank you for sharing! Funny story about prepping car for customers, not only was their vehicle repaired, it felt a lot more responsive to them!

 

With the manual transmission it has an idiot light on the dash telling you when to change up (for good fuel economy)… it always came on way too early for my liking… over time it gradually came on later and later as it learnt my driving habits, but I got sick of it and pulled the bulb… learn that!

 

Only the 1500s had that right?