Those cars that turn off stupid questions. Just curious

I haven't seen any issues, although I do note that vehicles with it tend to have very beefy starters.  They also do battery condition monitoring but so does practically everything else.

What amuses me is when people deliberately lift their foot off the brake to restart the engine.  I do not know if this is because they panic that the engine is not running, or if they like to creep forward two feet five times per red light.  If it causes problems, then I approve, like I approve Ford PowerShift equipped cars punishing people who creep several times at lights.

wae said:

MadScientistMatt said:

Some of the start-stop systems track what cylinder the engine stopped at, and if it hasn't had too much time pass since the engine shut down, restart the engine by activating the spark plug on the cylinder that was ready to fire.

For real!?  Sometimes it's just freaking amazing to be living in the future!

I have experienced this once, and it is creepy! The engine just starts running with no prologue, making you wonder if you were just imagining that it was shut off.

codrus (Forum Supporter) said:

1) Generally speaking, auto stop/start isn't enabled until the engine reaches some threshold temperature, so it's not particularly hard on the engine.

Not just coolant temps either. I know GM products have 22 different criteria it has to meet before it engages auto stop-start, including:

• battery state of charge
• ECM internal battery state of charge
• Air conditioning or defroster not enabled
• brake pedal pressure
• reaching a minimum speed since last stop-start cycle
• vehicle must be in drive

I will say, as a GM tech, I've never replaced a starter on anything with stop-start system prematurely. 

The whole concept smacks of "nanny state" to me.   My ex-wife's Ford Edge had it and I always shut off the stop/start option.

I remember one of the first time I drove a stop-start car at work, I had to take it to get fuel before putting a bunch of miles on it to set OBD monitors. When I say I had to get fuel, the needle was below empty. So I head towards the gas station, driving gingerly, and a stoplight turns red. I come to a stop and the engine shuts off and immediately my first thought is "Oh no, I just ran out of gas." I went to shift to Park to try and restart it, and as soon as it came out of Drive, it started the engine again. Phew, wiped the sweat from my brow and made it to the gas station,.

Jesse Ransom said:

I read the title to mean "cars which deter those questions which are stupid."

I wasn't sure what might have been meant by that.

I wish my cars would turn off stupid questions. Instead, they just seem to attract them.

My 2018 Cruze had start-stop, worked pretty good, except it was a bit too quick to activate, especially at stop signs. There was a capacitor by the battery in the hatch that was for quick restarts, it definitely started quicker on start-stop than it did at cold start up.  Edit: If you put the shifter in manual shift mode (autotrans), it wouldn't do the start-stop then.

I know in highlanders, starting in 16? And standard in 19, there is a different battery because of the stop-start feature. Physically it's the same as a 24f (which can be installed if the stop-start feature is disabled properly) but I think it has a higher reserve? Idk that much about the system really. I do find it annoying, but I'm a mouth breathing forest burner who dislikes kittens and the elderly. 

Pete. (l33t FS) said:

wae said:

MadScientistMatt said:

Some of the start-stop systems track what cylinder the engine stopped at, and if it hasn't had too much time pass since the engine shut down, restart the engine by activating the spark plug on the cylinder that was ready to fire.

For real!?  Sometimes it's just freaking amazing to be living in the future!

I have experienced this once, and it is creepy! The engine just starts running with no prologue, making you wonder if you were just imagining that it was shut off.

We've done a lot of looks at other cars, and I'm really not aware of anyone who has pulled that off.  It's more likely that the really subtle systems are starter-alternators- which make a whole lot less noise.

The really hard part about doing it really reliably and repeatedly is that you can't really tell if the engine spins backwards at all during the shut down.  And since that happens pretty often, well...

jharry3 said:

The whole concept smacks of "nanny state" to me.   My ex-wife's Ford Edge had it and I always shut off the stop/start option.

Do you also consider engines that run at best spark for efficiency part of the nanny state?  Or even modern engines with EGR?  Start-stop and those are there for the same reason- reduce wasting fuel.

I've had a couple of different types of rental cars with the feature and all would shut the engine off the instant you came to a stop. 

I don't understand why they weren't programmed to wait about two seconds so the very common scenario of coming to a stop sign with no apposing traffic wouldn't cause the engine to stop.  I'm sure you're wasting gas, in addition to adding wear to many systems, in this situation. 

All of the rental cars I've had used engine driven A/C pumps so no power = no cooling and I was pretty annoyed one time while in Plano, TX with hot and muggy weather headed to a presentation.

None of the rental cars had an easy defeat button but I discovered that if I put the car in neutral, it wouldn't shut off the engine.

In reply to RX Reven' :

If the A/C was on, that usually defeats the shutoff.  Some cars do have a weird refrigerant accumulator deal to allow the A/C to function for a short time with the engine off, but they monitor vent outlet temp and restart as necessary.

In practice, the trend to larger and larger cabin spaces tends to make the air conditioning suck, regardless if the engine is running or not.  The paradigm is now 30 degrees of temperature drop.  So if it is 105 out then the vents are blowing 75 degree air, which is IMO thoroughly inadequate.

It is easy to blame 1234yf but I have serviced cars with the gasified gold and got 40 from the vents on a 85 degree day, so clearly it's possible to have A/C that doesn't suck.

jharry3 said:

The whole concept smacks of "nanny state" to me.   My ex-wife's Ford Edge had it and I always shut off the stop/start option.

Uhhh, why?  Maybe if you gave it a chance instead of totally prejudging it, you might find it's really not an issue.

Both our Volvos - 2017 and 2019 - have it.  It's totally transparent to the driver and I have never been in a single situation where it has been a problem.

In reply to Pete. (l33t FS) :

That may or may not be a regulation. For most commercial buildings you are not supposed to design HVAC systems that can lower the temperature more than 30 degrees. It's part of the International Energy Conservation Code.

Pete. (l33t FS) said:

In reply to RX Reven' :

If the A/C was on, that usually defeats the shutoff.  Some cars do have a weird refrigerant accumulator deal to allow the A/C to function for a short time with the engine off, but they monitor vent outlet temp and restart as necessary.

In practice, the trend to larger and larger cabin spaces tends to make the air conditioning suck, regardless if the engine is running or not.  The paradigm is now 30 degrees of temperature drop.  So if it is 105 out then the vents are blowing 75 degree air, which is IMO thoroughly inadequate.

It is easy to blame 1234yf but I have serviced cars with the gasified gold and got 40 from the vents on a 85 degree day, so clearly it's possible to have A/C that doesn't suck.

I think the specific rental car I had in Plano was a Chevy Impala and the instant I stopped with the AC on, the engine would shut off and the vent velocity dropped by 50+%.

I'm not a hater but I do think the concept has been overplayed...overly generalized mandates or engineering to the test rather than reality or ???.

alfadriver has done actual engineering on these systems so I wouldn't second guess him but I just can't understand shutting the engine off when you're going to be calling for power in literally like one second.

I've spent about six months of my life visiting Minnesota (usually when it's about minus 20 degrees) and I'm worried about what is going to happen when these cars are nearing end of life...are they smart enough, are their sensors accurate enough, etc. to say "hey, we're an old beater and it's deadly cold outside, let's keep the occupants safe by not trusting that the engine will restart".

Not to add fuel to the hater fire but I do have concerns.

In reply to RX Reven' :

The vent speed drop may have been part of the battery protection scheme.  Load shedding when there is insufficient charging.

Also, the air blows colder when the fan speed is lower.  The BTU absorption available is spread over less air mass, so greater temperature drop.

As Nick pointed out upthread they monitor battery condition and will not shut the engine off if it is too discharged, or low in capacity.  I'd also like to say that most systems will not shut the engine off if there is a fault code present.  I remember discovering that a certain Cruze would shut off at lights only after I performed repairs and cleared it.  Somewhat disconcerting when it did not do that on the pre-service road test, and I'd just cleaned the throttle body and replaced the MAF 

In reply to RX Reven' :

because the internal temperature was within a certain spec of what was desired?

I know on my '16 FoRS that it will turn the engine off with the A/C on and the fan speed drops.  If it gets too warm or if I change the temp on the HVAC, it will turn back on.

Also if I'm stopping and starting a lot (crawling in traffic or dealing with stop light creepers) it won't turn the engine off if I stop again moving again within a few seconds.

Of course this feature with a manual is (I think) slightly easier than with an automatic, since you have to be in neutral with your foot off the clutch in order to engage the system.  So there will be a delay from wanting to move to when you can actually move, so by the time you're in gear, rolling on the throttle and applying the clutch, its already started.

There is a button you can hit to turn the feature off, so if it bothers you, you can easily disable it.

Reading this thread, you can almost tell who commutes in gridlock traffic and who doesn't.

The first time I ever experienced the auto start feature was a manual trans Fiat rental in London... I honestly thought the car broke

In reply to RX Reven' :

the biggest problem is a very uneven way of applying it.  Not sure how the systems will converge on a good way of doing it, but that would deal with most of the issues people see.

As for the one second thing- it's hard to know exactly what the driver is going to do.  It could be a one second pause, it could be a 1 min stop.  So you have to do your best to deal with the spread.

And I would hope that the many layers of gates allowing it to happen will detect when the engine should not shut down as it ages.  I know it does take a while for the battery state of charge to get high enough- we have a '20 Escape that it was not working for most of last month, since we were driving really short distances.  

Which is all to say- your concerns are very valid.  

Anyone ever driven a manual with one?  I hear they are not nearly as intrusive since they only shutoff if the car is in neutral, and start when you push in the clutch.

A casual search seems to show maybe a few % increase in fuel mileage and that of course requires a fair amount of stop and go driving.  It smacks a bit of the "you must bring your car to the dealer to have it learn your new battery" BMW thing.  That is apparently, a rather complex solution to get some very small returns in mileage and seems to be primarily for the benefit of the automaker, not the customer.

I find it annoying and mostly unnecessary for my purposes.  Some of the early implementation are very clunky.  Had a work friend with an X3 with it and it was very non-luxury when the car shook to a start after stopping.

In reply to red_stapler :

If I commuted in gridlock traffic, I'd have a hybrid or EV yesterday.

In reply to ZOO (Forum Supporter) :

It's a 2021 with the DSG. I'm sure the time to start and move isn't all that long, but many cars start moving from a red light before I can.

alfadriver said:

jharry3 said:

The whole concept smacks of "nanny state" to me.   My ex-wife's Ford Edge had it and I always shut off the stop/start option.

Do you also consider engines that run at best spark for efficiency part of the nanny state?  Or even modern engines with EGR?  Start-stop and those are there for the same reason- reduce wasting fuel.

EGR is primarily for fuel economy, really?  Tell us more.

Seems fairly obvious the starter would wear out sooner, but that happens out of warranty, and drives the repair business at the dealership.

In reply to Toebra :

Has been for about 20 years now.  Once everyone figured out a/f control to make the catalysts really work, EGR for gas engines wasn't needed for emissions.

For FE, you can run higher compression and lower pumping losses with EGR, very much offsetting the worse combustion- so it ends up being a significant fuel economy benefit.  Largely outdone for the last 15 years with TI-VCT, but there's research to bring it back again.