I have heard some say that performing a CASE relearn is strictly for diagnostics and the computer does not use the info during normal engine operation other than to detect misfires.

I have seen others say that it does use the info to help run the engine. Some even go so far as to say that performing the CASE relearn has solved some misfire issues for them.

According to the Alldata Step 1 in diagnosing a P0300 random misfire code is to make sure there are no other codes present. Step 2 is to perform a CASE relearn.

What is your opinion? Diagnostics only or essential to operation also?

J. J.

 

No one has any input on this?

J. J.

 

The PCM knows the position of the crank at any time from the encoded 24x reluctor wheel on the crank, regardless of whether a CASE relearn has been performed or not; the PCM synchronizes injector and ignition events on the crank position; so the PCM will run the engine just fine;

the CASE relearn allows the PCM to measure the rate of crank deceleration, this is what the PCM will use to determine if a future ignition event is a misfire;

if the PCM thinks it is seeing misfires (i.e. if a CASE relearn has not been performed, or the rotating assembly does not match the PCM's learned CASE data), then the PCM may take some action to protect the catalytic converters and this may or may not affect performance.