Fluttering going up hill slowly

Tron907 said:

I have a 2014 cadillac ats 3.6L awd. While going uphill at about 10-20 mph it feels like the engine is fluttering, if I get on it, it goes away. There is no check engine light, no codes to read! What could the problem be? Check engine light is not flashing, so I kinda ruled out a misfire.

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Fluttering is kind of confusing. Are you "lugging" the engine? Try downshifting without increasing your speed. That will raise the engine revs. The programming of some of these cars is designed to upshift early in an attempt to increase fuel mileage by decreasing revs, but at times that can cause lugging, which eventually leads to nasty things like carbon buildup or ring failure. See if a lower gear smooths things out.

Melze said:

Fluttering is kind of confusing. Are you "lugging" the engine? Try downshifting without increasing your speed. That will raise the engine revs. The programming of some of these cars is designed to upshift early in an attempt to increase fuel mileage by decreasing revs, but at times that can cause lugging, which eventually leads to nasty things like carbon buildup or ring failure. See if a lower gear smooths things out.

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Have you ever figured it out? I have the same issue in my 2015 ATS.

No I never did figure it out.

As Melze noted, the programming of the 3.6 and 6L45 transmission in the ATS will result in it shifting very early under certain conditions causing light "spark knock". My 2014 ATS RWD 3.6 premium trim will do this on moderate upgrades at slow speed, I just paddle down a gear to stop it. It is part of the fuel economy programming. Fuel on the margin of meeting the 87 octane rating along with degraded spark plugs and/or coil packs will make this problem more noticeable.

I also have a 3.6 in my 2021 Camaro RS but the powertrain programming with the newer 10 speed auto is far more refined and it never has showed that quirk like the ATS.

Rodger