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Why does the rpms get high when changing gears?

I have an automatic 2012 with 108,000 miles. On cold start, car sometimes will have a high idle, but not too bad. The main problem is that the rpms get high when I shift gears. I've taken the car to 3 mechanics and they can't find the solution. There's no air leaks. Throttle body, throttle position sensor and mass air flow sensor replaced. I've had mechanic do a tune up, oil change and I got new battery. Transmission place told me the transmission is good, that it shifts hard because of the high rpms. I don't know what else to do. Thanks.

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I think we'll need some more details. Is it happening when upshifting? Does it happen every single time the transmission shifts gears, or only at certain times? How high up do the RPMs get?

As for a high RPM idle during startup, that's completely normal as the engine tries to warm up from a cold start (usually no more than 500-1000 RPMs above a normal idle when warm.

On cold start it goes upto 2000-2100 rpms, then it stays idle at 800 rpm. At shifting to any gear, it goes to 1500 rpm. On reverse it idles at 600 rpm. On other gears it idles at about 800-900 rpm. I hope it doesn't sound too confusing.

So for example, when you shift from Park to Drive, it revs up to 1,500 RPMs? How long does it stay there before it goes back down?

When I shift from Park straight to Drive, it goes from idle of 900rpms down to 600rpms right away.

But, if I shift from Drive straight to Park it goes from 600rpms to 1500rpms for about 3 seconds(about 10 sec total to gradually come down to idle 900rpms). Same with Reverse to Park and Reverse to Neutral.

Have you found the source of the issue?

I have the same issue RPM goes to 1500 for around 3 seconds then back to 800.

This started right after I cleaned the throttle body. Nothing was wrong with the car in the first place but my itchy hands had to fix something that wasn't broken…

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Based on your follow-up comments, this all sounds like normal RPM ranges. 2,000 RPMs right at startup is normal, just as long as it goes back down after a few seconds or so. (it may stay higher for longer when it’s really cold out).

As for shifting into Drive, the RPMs will slightly go down because the engine connects to the transmission, and the resistance of the transmission fluid takes energy from the engine and lowers the idle speed slightly. Vice versa, when shifting into Park, the RPMs will go up temporarily because that resistance is no longer there. Your car’s computer will notice this and bring the idle RPMs back down to the normal 800-900 RPMs.

That’s all a bit oversimplified, but I hope it makes sense. There doesn’t appear to be anything wrong based off the info you gave.

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What if the car is automatic. U dear normal conditions, what rev range should it change gears. I have a clk 200 2009., 1.8.

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