Push to start cars

[JHZR2]

Just curious - how does a car with a start button know when it actually has "caught" and can disengage the starter?

In a traditional key car, the person is the logic, and can crank it as long as they want. Some cars now have a smart starter so you cant grind it after the car starts, but those cars dont actually do the starting for you.

How does the start button recognize that the car has indeed started? Wheat happens if the car does not catch, does it only crank for say, 15 seconds?

 

[The_Jeff]

Was reading about a mid 2000s GM truck where you turn the key in the normal way and if you hold it longer than 1/2 second it keeps turning over until it catches, or until the presumed timeout happens.

Easy enough to make a starter drive (bendix style?) where if the engine goes faster than the starter gears it spins them back away from the flywheel. I imagine, like aftermarket remote starters, there's a RPM sense and the sense of voltage lowering then raising again.

Cadillac had an auto starter circa 1960. Pump the gas to set the choke, turn the key on, and it'd start for you. Back up of a manual start position.

 

[KrisZ]

Quote:
I imagine, like aftermarket remote starters, there's a RPM sense and the sense of voltage lowering then raising again.


That's pretty much it, there is a sensor that reads voltage for the RPM, the cranking time is probably 1.5-2.0 sec. and if after that the rpm is 0, the car knows to try again. A lot of remote starters work this way and I think push button starters use the same technology.

Some remote starters even let you adjust the cranking time, shorter for summer and longer for winter, pretty smart.

 

[RF Overlord]

I suppose it would be easy enough on today's computer-controlled cars to sense the RPM increase when the engine fires and use that signal to disconnect the starter.

My buddy's '08 Escape Hybrid is similar in that when you turn the key, it doesn't matter how briefly you hold it in the "start" position, the starter doesn't release until the motor catches, even if you've already let go of the key.

 

[ARCOgraphite]

My 08 toyota yaris has a key - but automatic start logic - you just click the key to start for a 1/4 sec and let the ECU take over.

 

[bepperb]

Most remote starters read the tach sensor and when it hits an rpm over what the starter can do stop cranking.

 

[JHZR2]

Originally Posted By: KrisZ

Some remote starters even let you adjust the cranking time, shorter for summer and longer for winter, pretty smart.


See, I feel that this is dumb unless it disengages right at the time when the engine "catches". Otherwise the starter is spinning an undue amount. Id rather it be intelligently controlled, perhaps with a max time to start as a variable. Wouldnt want it cranking for the sake of cranking.

 

[KrisZ]

Originally Posted By: JHZR2
Originally Posted By: KrisZ

Some remote starters even let you adjust the cranking time, shorter for summer and longer for winter, pretty smart.


See, I feel that this is dumb unless it disengages right at the time when the engine "catches". Otherwise the starter is spinning an undue amount. Id rather it be intelligently controlled, perhaps with a max time to start as a variable. Wouldnt want it cranking for the sake of cranking.


A remote starter like that will have an RPM sensor and the timer working together, so if the cranking limit is set high, say 3 sec. and the car starts before, the sensor will override the 3 sec. cranking time.

Cranking time has to have a set limit, otherwise if you're only relying on the RPM sensor, there may be a condition when the engine doesn't start, blown fuel pump fuse for example, where the starter would just keep cranking the engine over and over. A lot of starters also have a limit of failed starts as well, to protect the starter and the battery.

 

[GMBoy]

It's not just the push to start cars - most cars past about 2000 auto crank for you no matter if you hold the key long or just flip it fast. Basically you turn the key (or push the button) and the PCM energizes the circuit and stops the starter when the crank sensor shows the PCM that the engine has started. Really, the starter switch (button or key) cannot hold the starter on longer than needed. Even my 2006 GMC is like that - I can just flip the key real fast and the starter will still go as long as needed or I can keep the key on but it won't crank anylonger. This setup also prevents you from engaging the starter when the motor is running.

 

[mechtech2]

The push button is the exact same thing as a key starter.

 

[Rhymingmechanic]

I thought you meant the kind of car that needs to be parked on a hill. I'm learning a lot from this thread, but also can't help thinking that just because a vehicle's computer CAN be made to do something doesn't mean it's a good idea to automate everything.

 

[Rhymingmechanic]

Another thought: You used to turn the key and crank until it started, or turn the key and hold the push-button until it started. Inconsistency among models seems like it could lead to problems like the runaway Lexus incident, where holding the button to kill the engine was apparently not intuitive for the driver.

 

[GMBoy]

Originally Posted By: mechtech2
The push button is the exact same thing as a key starter.


That's what I was saying but with too many words LOL!

 

[Nick R]

I don't understand the fascination with push button starting anyway. Is it really THAT big of an inconvenience to put a key in and turn it? I mean I'm the pro automatic, pro doo dads, but this just is beyond lazy.

 

[rationull]

Originally Posted By: rudolphna
I don't understand the fascination with push button starting anyway. Is it really THAT big of an inconvenience to put a key in and turn it? I mean I'm the pro automatic, pro doo dads, but this just is beyond lazy.


I hate to say it, but when combined with keyless entry (not remote locks but the feature where you actually don't need to get the key out of your pocket to unlock the door and get in the car) it would actually be pretty nice to not have to take the key out to turn the car on, either.

 

[ekpolk]

Originally Posted By: mechtech2
The push button is the exact same thing as a key starter.


Yes and no. In conventional cars, I get what you and GMB are saying. But you still have the "problem" (if you even call it that) of not being able to turn the key backwards. All the Toyota/Lex hybrids are push button start, and for the most part, I like it. It is annoying, however, if you pull into the garage and you'd like to keep talking on the phone (hands free, of course...) or listening to the radio, you can not shut the system off without killing the electronics too (as you can by turning a key back to the "accessory" position). You have to turn it all the way off, then push the button again to get back to "accessory".

On the other hand, I really like the overall system. Driving my car never involves reaching into my pockets any more. As I approach the car and touch the door handle, the car senses the fob (in my pocket) and unlocks the doors. I sit, foot on brake, push button, and a moment later, we're ready to go. Leaving the car, I close the door, and push the little button on the door handle and it's locked.

 

[rationull]

Originally Posted By: ekpolk
It is annoying, however, if you pull into the garage and you'd like to keep talking on the phone (hands free, of course...) or listening to the radio, you can not shut the system off without killing the electronics too (as you can by turning a key back to the "accessory" position). You have to turn it all the way off, then push the button again to get back to "accessory".


I don't follow. In HSD cars won't the engine most likely end up turning off when you stop in the garage anyway? Is the state where the engine's off and the car's stopped meaningfully different from the "accessory" mode if you turn it off and on again?

(I'm assuming I'm just not aware of some difference here).

 

[Papa Bear]

First car I ever drove was a '48 Ford, it had a push button start.

 

[ekpolk]

Originally Posted By: rationull


I don't follow. In HSD cars won't the engine most likely end up turning off when you stop in the garage anyway? Is the state where the engine's off and the car's stopped meaningfully different from the "accessory" mode if you turn it off and on again?

(I'm assuming I'm just not aware of some difference here).


Sometimes the gas engine shuts right off, sometimes not, it depends upon multiple factors such as state of charge, engine temp, etc. Here, you're still in "READY" mode, until you press the button, which takes you directly to OFF mode.

Unlike a key car, you can't turn the "key" backward. Each push of the button moves you "up" one mode, until you choose to select "READY" with a push combined with the brake pedal. To get back to "accessory" you have to go back to OFF and start again. This causes all electronics to shut off. A minor annoyance.

 

[ekpolk]

Originally Posted By: Papa Bear
First car I ever drove was a '48 Ford, it had a push button start.

Did it have a key too, or just the button? For the record, I was born in 1961, and have no idea when cars first started getting "keyed".