Hello Gents,

I searched around a bit, but couldnt find much on Drive Cycle info. Just curious if anyone has any knowledge of the time/method it takes for the stock PCM to "re-learn" and make adjustments after its been reset?

I also presume its continually learning/adjusting on the fly correct?

Reason I ask is that I have done a few mods/repairs, and suddendly it appears to be getting a bit better fuel economy (after I took it on a 2 hour drive on the Interstate). Didnt know if somehow it was able to run long enough at a constant RPM/Temp/etc to make the fuel trim adjustments and what not.

I am not complaining, just curious if Dodge's have such a thing, or if I am just trying to convince myself the MPG's are better.

Thanks!

 

I had a check engine light on my Hyundai,the code was for the O2 senser and was due for inspection. Simple fix slapped in a new sensor. I disconnected the battery when the new sesnsor went in. So the PCM reset. Little did I know.

The drive cycle is a very picky thing. 250 miles after the switch & at inspection station the PCM was still not fullyreset.

My advice to everyone is give it a month or 500 miles. DON"T disconnect the battery a month before inspection.

Jeff

 

200 miles ... Ilove peoplewho bring there rides in just after they unhook the battery and say : i didnt do nothing , well your nothing just failed emmisions..HA HA

 

That sounds pretty close to when I noticed mine start to perk up and run a bit better. I had heard stories of guys unhooking the batter prior to a drag-run, but who knows.

Thanks!!!

 

A 'drive cycle' sometimes called a 'global cycle' is about a 30 min road test.
You have to start with a cold engine and during the drive cycle it has to warm up fully to operating temp. Your drive has to have some stop and go driving, at least 5 mins of idle and at least 5 mins of sustained (highway) driving. This puts your engine through all the various types of driving and allows the PCM to run all it's self tests.
This type of road test should be performed after any engine or sensor repair to verify a successful repair. It is often not performed or performed properly due to time or conditions buy many tech and often leads to comebacks.

You are right that the PCM is continually 'learning' and adapting whenever you drive. 250 miles of various driving should be enough to relearn after a reset.