My mustang has a mind of it's own

So the past two days I have noticed my car will start revving when I am going down hill or braking.

I have a 2016 gt auto that doesn't get driven too often and all of a sudden it's doing this. I will be going 30 or less and when I stop the engine spikes up to 2k and is audible.

Is this just some delayed down shifting ? It's new and freaks me out because I want to slow down and yet the car revs and accelerates a tiny bit.

Are you in S mode?

You need to beat on her more :headbonk:

No I'm in normal drive mode when it happens. It's also not a quick blip. It lasts a solid 5 seconds or more.

Coolmanfoo said:

No I'm in normal drive mode when it happens. It's also not a quick blip. It lasts a solid 5 seconds or more.

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How about when you just sit idling in neutral?

Mine does weird stuff like that. Try hypermiling down a long hill, let off gas, move to neutral, revs will shoot up and stay up, like the car is trying to maintain vacuum or electrical current based on speed the car is going, not based on fact you requested car return to idle by takin foot off gas and coasting in neutral.....dang computer. It uses more gas than just keeping it in gear and driving...not like old days....

RIBS said:

Mine does weird stuff like that. Try hypermiling down a long hill, let off gas, move to neutral, revs will shoot up and stay up, like the car is trying to maintain vacuum or electrical current based on speed the car is going, not based on fact you requested car return to idle by takin foot off gas and coasting in neutral.....dang computer. It uses more gas than just keeping it in gear and driving...not like old days....

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Not really. Those modern high compression V8's have pretty strong engine braking. When you lift off the gas at speed, the throttle body does not close all the way to provide a more smooth transition as well as normal feeling engine braking. You don't want the car to slow down too fast when you lift off the gas.

jasonstang said:

... You don't want the car to slow down too fast when you lift off the gas.

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GTP said:

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It's called engine braking. If it's too much it will feel jerky.

jasonstang said:

It's called engine braking. If it's too much it will feel jerky.

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Which mode?

GTP said:

Which mode?

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I dont think there is a difference from what I can feel.

I would want max engine braking, combined with how the car stays in lower gear when in Sport mode.

GTP said:

I would want max engine braking, combined with how the car stays in lower gear when in Sport mode.

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I have not seen any car with max engine braking since fuel injection.
They all somehow opens the throttle a bit when letting off the gas pedal.

jasonstang said:

Not really. Those modern high compression V8's have pretty strong engine braking. When you lift off the gas at speed, the throttle body does not close all the way to provide a more smooth transition as well as normal feeling engine braking. You don't want the car to slow down too fast when you lift off the gas.

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I am not talking about letting off in gear and engine braking keeping the RPMs up. I’m talking about dropping it in neutral and letting off the gas and the revs will stay as high or higher in the car was in drive and will stay there forever.