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Am test driving a 2008 3.9 which has AFM and 140k miles. What should I be looking or listening for to see if it has any engine issues related to the AFM? Any other known issues I should be aware of, like AT? Thanks in advance.
 

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Am test driving a 2008 3.9 which has AFM and 140k miles. What should I be looking or listening for to see if it has any engine issues related to the AFM? Any other known issues I should be aware of, like AT? Thanks in advance.

I purchased a new 2008 Impala LTZ with the 3.9 / AFM engine. I no longer own it.

The AFM feature was discontinued by GM on that engine after two years of use. Parts specific to the AFM feature are no longer offered by GM and there is a TSB on how to “convert” the 3.9 AFM engine to a non-AFM engine if problems with the system are encountered. Somewhat expensive....

I had not problems with the AFM system. Regular oil changes with a quality oil filter is critical to ensure the smooth operation of the system.

You can scroll through the DIC screen and there is a specific screen that shows the engine transitioning from six to three cylinder mode (check the owner’s manual if you are unfamiliar with the DIC - but it is easy to use).

You could set the DIC screen to the AFM mode display - then drive the vehicle and see if you can feel any difference as the system changes in and out of AFM mode. On the Impala I had - it was very difficult to detect the switch, even watching the DIC screen switch between the two modes.

Good luck.
 
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