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I am looking for an aftermarket device that turn off the engine when the car is in rest and turn on the engine when the throttle is pushed. Which are the producer? Where i can find it on internet?

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Just to clarify: you are asking for an aftermarket system that replaces the action of the ignition key? As in, come to a red light, turn the engine off? – Bob Cross Aug 13 '12 at 17:44
Auto start-stop means that when you come to a complete stop but remain in gear, the engine turns off, and then re-starts before you drive off. Different companies have implemented it differently (and for auto/manual). On my car, releasing the brake restarts the engine. All new BMW's have this. There are various implementations - some use the starter, some don't. – Steven Aug 14 '12 at 2:41
@StevenBerkovitz, yes, I'm familiar with the principle and the implementation in BMWs. The original post was very spare in terms of word count: I'm trying to ensure that someone trying to answer the question knows what to answer. – Bob Cross Aug 14 '12 at 11:55
I suspect than any aftermarket solution, if it exists, will be ridiculously expensive to have installed. Even if anybody would be willing to install it. – Mark Johnson Aug 14 '12 at 21:32
I am asking for a general solution. – emanuele Aug 15 '12 at 20:06
up vote 1 down vote accepted

I don't know of an aftermarket system out there currently. But it wouldn't be that difficult to do. General Motor's "Green Line" Hybrids have removed the starter and replaced the alternator with a generator/starter much like some older farm tractors. The have a 36 volt battery to handle the additional power requirements for starting.

There are some additional things you will have to overcome, like your AC not working with the engine off, modifying the programing on fuel delivery. Again it's should be doable from an aftermarket standpoint, just has they have the propane or CNG conversions that can be done to a gas car.

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Auto start/stop requires design changes to the starter, flywheel, solenoid, charging system, among other things. A traditional starter isn't rated for the duty cycle that a start/stop system requires. The flywheel and starter are also changed do that the engine can start faster. The solenoid has a higher duty cycle. The charging system has to be designed to run the electrical systems for longer with the alternator being offline and also intelligently monitor the condition of the battery to know it'd charge level and health accurately to guarantee enough juice to run the starter. Plus other non-trivial changes to the fuel delivery system to slow for fatter shutdown and startup.

All of this adds up to be too much to put in to an aftermarket system.

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