Important information regarding Misfire Detection and the Crankshaft Variation Relearn Procedure (aka: CASE Learn) in GM OBD2 systems:


Most 1997-newer GM OBD2 computer systems require a CASE LEARN to be done if the PCM, engine, crank sensor, crank balancer, or any related parts are replaced or changed.  Sometimes, a CASE Learn is required if the PCM is reprogrammed.  If a CASE Learn is required and not done, a P1336 or P0315 code may set and turn on the check engine light.  The engine may be operated during this period with this code set but it is not recommended the engine be driven hard until that procedure can be done.


The CASE Learn is essential if you wish the computer be able to accurately detect engine/cylinder misfires.  A good scan tool (or good scanning software running on a laptop/pc) is required to begin the CASE Learn procedure.  The entire procedure takes about 2 minutes to do if the engine is already fully warmed up.  But if you are paying a repair shop to do it, they may elect to charge you for a minimum amount of diagnosis or hourly labor time despite the short amount of time the procedure requires.  It would be a good idea for you to research how much it is going to cost you to have a CASE Learn done by your local shop BEFORE you purchase a custom tune from us.  Remember, in some cases, a CASE Learn may not be required for most customers (but this is usually only the case if you are sending us a PCM to be custom tuned that came from the same vehicle and engine you are working with).


The CASE LEARN procedure and related trouble code CAN BE DISABLED in a custom tune, but doing this also requires the misfire detection system (and P0300 misfire codes) be disabled as well.  Doing this will remove the misfire detection abilities from the PCM's on-board diagnostics, but otherwise will not affect how the engine runs and performs.  PLEASE LET US KNOW IF YOU WANT THE CASE LEARN / MISFIRE DIAGNOSTICS DISABLED IN YOUR CUSTOM PCM TUNE WHEN YOU PLACE YOUR ORDER.


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