My 2011 Toyota Tundra has a automatic transmission and only about 17,000 miles on the clock. When I leave it idling it will randomly increase revs about 700 rpm and then gradually bring that down over a couple of minutes. Not sure what to do and not sure if this can even hurt the truck. What is happening here?
Your engine control system is constantly making adjustments in relation to the various input signals it receives. Some idle changes are normal adjustments to a number of things that may be occurring. For example if left idling for a long period, things such as engine temperatures, A/C, defrost operations or exhaust temperature, can all trigger a response from the engine control system to adjust the idle speed. RPM speeds in the range you describe are not uncommon. If the speeds seem to be erratic or extreme, then have a qualified service mechanic, like one from YourMechanic, inspect your engine's high idling speed for any abnormalities. Keep in mind that it may result in finding no problem, unless there is a failed component.
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