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I currently live in Japan where I bought a 1997 Subaru Impreza WRX STi. Since I don't completely speak Japanese, I wasn't able to ask anybody correctly about one thing that the previous owner had installed, which is a small timer under the steering wheel that does, it seems, different things. Here is the pdf I could find on it

One of the things it does is to prevent my car from shutting down after I turn off the ignition. I can turn towards me and remove the key, and when I do, nothing happens. However, the timer starts, and after 60 seconds, the engine turns off. There is a button that allows me to turn off the engine before the end of the countdown, and when I disconnect the battery to change something, and reconnect it after, the timer's default behaviour is to not activate itself, and in such case the engine will turn off as soon as I turn the ignition off.

My question is, why would somebody want to delay the engine shutdown like this ?

P1kachu
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1 Answers1

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It is a turbo timer.

The theory is that an engine with hot turbocharger shouldn't be immediately turned off. The turbocharger may be damaged because there will be no oil flow. The timer ensures that the turbocharger has managed to cool down enough by idling.

Now, do you actually need the turbo timer? Probably not. The turbocharger is hot only after hard driving. Usually, the last few hundred meters of your driving are near a parking area with low speed limits, meaning there is already enough time for the turbo to cool down.

If you drive hard and turn the engine immediately off, on the other hand, you may benefit from the turbo timer.

juhist
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