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Infiniti G35 Automatic Transmissions
Basically what is happening is that around 40 mph or so, or slightly thereafter, my car upshifts, but the upshift is extremely hard and not fluid at all. The car almost jolts itself, and I can feel vibrations in the peddle from the engine. This usually only occurs when I am accelerating slowly. Fast acceleration there is no problem. There also isn't an issue when I'm in the tiptronic mode, so my guess it has something to do with the programming of the automatic transmission.
I think when it shifts it is switching up to 4th gear... it's never occured when downshifting, only accelerating slightly in automatic. I recently had a 30,000 mile service completed, and they replaced the transmission fluid, so it's definitely not that. Otherwise I stay up to date on all oil changes and other service appointments.
Does anyone know what might be the cause of this problem? Any help is appreciated. Thanks!