this is false. if the transmission was going into neutral every time, it would “slam” into gear once hydraulic pressure was restored (most transmissions use the torque converter snout to drive the front pump.) As I said above, the transmission needs little more than a simple hydraulic accumulator to maintain line pressure while the engine is stopped.
it stops the compressor, but the evaporator doesn’t immediately assume room temperature. and, as I said above (AGAIN!) auto stop/start will not activate if it will cause the climate control system to deviate too far from the set temperature.
what on earth are you talking about? the starters are not permanently engaged. They’re the same as starters have been for decades.
oil pressure is meant to get oil to where it needs to be. a certain level of pressure isn’t required in order to maintain a certain film thickness. further, as I said, the galleys haven’t drained, so the instant the oil pump starts turning it’s pushing oil through the engine. we’re talking hydraulics here, oil is incompressible. it goes where the pump pushes it, as fast as the pump can push it, and has no choice in the matter.
Emissions warranty is 8/80 per federal law. It’s not the powertrain warranty. And the “start/stop system” is basically the powertrain control module (PCM,) which is covered under federal emission warranty as it is for all cars.
you have some serious misconceptions (and some outright wrong ideas) on how this stuff works.
I think a little research will help you.
Here for example : *The US National Highway Traffic Safety Administration (NHTSA) raised questions about non-hybrid Honda vehicles equipped with the company’s ‘Idle Stop’ transmissions in February 2001 due to concerns over the “sudden lurching forward of a vehicle in an automatic restart” – rather than the "gradual creeping forward found in current transmission designs *cite
Some manufactures like BMW include an Auto Hold feature that allows the driver to release the brake pressure. Some others do not. The brake booster works with vacuum from the engine, when the engine is off depending on vacuum leaks (not likely) driver may need to put in more pressure.
Agreed - but this is an additional control. And every new logic introduced has the potential of failing and there is no reliability data.
The traditional starters had to boosted up to reduce wear and tear on the flywheel/ring gear. The brushes had to be beefed up too. But still it was not so good for this application. Denso developed two types of starters Tandem Solenoid to reduce startup time (cite) and Permanently Engaged Starter with Toyota.cite
I know it sounds that way, but you’d be surprised.
The Prius is a famous example of this technology. It uses synthetic lubricants, and from engine teardowns on PriusChat.com, there is minimal wear at 300k miles. I don’t know all the tricks that were used to accomplish this.
The primary reason why starting engines take time with older cars is there is a starter motor, it is kind of small compared to the electrical demands to crank the engine, and it’s connected by a small gear paw.
In a Prius, the starter motor is a large, high power, high voltage motor attached directly to the engine. It can turn the engine easily and remains connected at all times, there’s no mechanical linkage that disconnects and reconnects. It turns the engine and as each piston reaches the right point to start a new combustion cycle, fuel gets injected into that cylinder only, resulting in a smooth and basically instantaneous start.
There are some dampers in the system, making it such that as you drive a Prius you can barely feel it at all when the engine kicks in.
According to both consumer reports and My Mechanic data, the Prius is actually one of the most reliable cars you can buy, despite all the additional complexity of the hybrid systems. Most likely it is significantly more reliable than a Bolt or Tesla, despite having far more components. The reason is that a complex design that has been refined beats a simple design in it’s first year of production.
Fully agree with you SamuelA. Prius is a great car and I’d buy one if gas prices were predicted to go high.
Toyota had auto start/Stop in Prius from1997 but waited till 2009 to offer it in traditional cars. Hybrid cars like Prius have a high power motor which rotates and lubes the engine even before the fuel is sent in. Traditional cars don’t have this option due to the small battery.
There’s definitely good momentum in research to bring this system to traditional cars but it is still not a mature system for the issues highlighted above.
I loved car talk on NPR. And I think I agree with Ray Magliozzi, who said this a few months back : “It’s a little too early to say with certainty what, if any, downsides there are - other than the shudder, if that bothers you. “
I rented a car with start-stop a few months ago, and with some experimentation at stoplights, found that if I pressed the brake pedal just enough to stop the car, the engine stayed on, but if I pressed a bit more, the engine would stop. Exactly where that decision point is, I couldn’t say, other than farther than you’d ordinarily press in creep-and-go tollbooth traffic… It’s not like there was a beep, dash light or kickback in the pedal.
My brothers car had persistent brake issues which were caused by the brake booster wearing out the cam shaft, I’m glad that was a warranty repair. High tech car no thanks, I keep my dirty diesel till It’s time to go electric.
Good stuff. We have one of these cars at work and I’ve been curious about how the starting worked. When it kicks in pulling away from a red light I can’t feel the engine cranking, it just starts. I guess that’s because it doesn’t crank. This car is several years sold and I don’t know if its true with newer cars but the AC stops as well as the engine. At a longish light or stuck in traffic it gets warm in the car pretty quickly. Putting the car in neutral starts it up and keep AC working.
uh, what? the brake booster is usually a vacuum chamber mounted on the car’s firewall. how can it “wear out the cam shaft?”
what is it? if it’s a hybrid-electric vehicle, the engine gets spun up by one of the electric motor/generators in the transmission. if it’s a regular (non-hybrid) car with auto stop/start, then it still has a conventional starter. just doesn’t need to crank very long.
This thread has a similar character to other threads on a variety of forums, regarding new technologies. Ten or fifteen years ago, it was about the durability and efficiency of hybrid vehicles. Now it’s auto stop/start.
I know enough about automotive technologies and AS/S, and others have covered that side of it here. What interests me is the emotions that drive the resistance to these innovations. Why the dislike for AS/S ?
The dislike is that many of the posters here have dealt with unreliable cars their whole lives. Many American cars have had marginal reliability for decades, and European cars have become garbage for reliability in recent years. Even Honda started cost reducing around 2008 and their reliability went downhill.
Basically only Toyota - and not all models and years - has made consistently reliable cars for decades. Except for those Tanaka airbags and unintended acceleration.
So it feels like starting and stopping an engine is just one more reason to pay a mechanic to fix your ride.
I guess I’ve been lucky, my cars have been pretty reliable. The German and American ones less than the Japanese ones, but all of them more reliable than the cars that built in the ‘60s and ‘70s. But if I’d had to deal with more breakdowns, maybe I’d long for less complex cars, that I could fix myself.
The reality is, most modern engines don’t “wear out.”
General wear (rings, valve guides, journals, etc.) is rarely the cause of engine failure in modern cars. Something major, like a blown head gasket or oil starvation due to poor maintenance is more likely to result in an engine failure than simple wear.
And, if you see a car with obvious signs of wear (like blue smoke), then the body of the car is likely to be a wreck, too.
My wife has a 2008 Camry hybrid. The only real expense we’ve had was a thousand dollars plus of front end work to fix the steering and suspension due to bad roads. (your tax dollars not at work). The drive train works fine. It was a little disconcerting the first few months we had it, that the shudder of the engine starting happened about 10 feet after you start pulling out of the garage. The engine tends to run most of the time but will stop if we are waiting at lights and the AC or heating is not in high demand.
My 2014 BMW 328i stops whenever I come to a stop. It will start as soon as I take my foot off the brake, or try to turn the steering wheel (there’s a momentary resistance on the steering until the power assist kicks in). It too will kick in at a stop if AC or heat is needed; I assume the water pump is not running without the engine so in winter, the engine will restart within about 20 seconds. Typically, it stops at a red light of similar traffic stop. If I inch forward, it will not stop a second time (I guess the internal logic decides it’s “stop and go” traffic). I have to hit a decent speed or go a decent distance (exactly what, don’t know) before the auto-stop happens again. I don’t know what the transmission is doing, but I assume it disengages for the crank start.
In both cases the engines start in what feels to be one revolution, turn over and run within a second. None of the frequent cranking I remember from my really old cars. I knew someone who had T-bird, probably around 1985, and it had a bad habit of stalling at red lights randomly and not starting - usually in humid conditions around freezing… without benefit of auto-stop-start. She’d had it towed 10 times in less than a year. A hot engine does not always guarantee a start.
I guess the relative fuel economy depends on whether you do a lot of downtown stop-and-go driving (and the outside temperature).
This will be highly dependent on where you live and the kind of driving you do. If you live in a place where your commute is dominated by traffic jams and/or you do lots of driving in dense urban cores with lots of traffic lights, this is going to save you a lot. On the other hand, if you drive mostly open highways or move around a lot in the 'burbs where there are few traffic jams and lights, not so much.
I wonder what would be the issues with keeping the motor barely turning. E.g., firing a cylinder here and there. Make it a random one so that the vibrations don’t cascade.
So when it’s time to go the startup time is shorter and possibly more reliable.
How often would a cylinder have to fire to keep things reasonably going?
All this, of course, makes me think of those old cylinder farm pumps with a governor ball which fire, spin for a while, fire again, etc. Make a weird, whump … whump … whump sound. Ah, the good old days.
It doesn’t take a really dense urban area for these systems to show the kind of improvements quoted. In those cases (driving in Manhattan say) it would probably be even more. AFAIK tooling around most US actual suburbs (not ‘exburbs’) at work drive times requires plenty of stopping. Some prototypical ‘real Murrican’ exurban/rural driver (composing maybe 10% or less of actual drivers) go on such open roads all the time it wouldn’t make any difference. Then again the already overblown IMO predictions of maintenance nightmares would not come to pass for them either, because the system would hardly ever be activated.
Sincerely,
Grand Admiral Obvious (for the last part)
It’s also IME obvious factually (maybe not emotionally, obviously not) that complication and reliability of cars do not correlate all that closely if that’s all your look at. Cars now in general are vastly more reliable (in the strict meaning, not stuff like ‘I can work on it myself’, that’s not reliability) than 1970’s cars (I remember first hand) and much more complicated. It’s also highly doubtful IMO now between recent model cars. Toyota might have the best reliability record overall in say the last decade or two, but it’s not particularly because their cars are simpler than say the big US brands. They have some kind of institutional edge on quality/reliability even at the same level of car complexity. It’s not national characteristics of assembly line workers since Toyota replicates their formula at factories around the world. It might be national characteristics of engineers to some degree since they are mostly though not entirely in Japan. Anyway the US brands have just never been able to catch up model year for model year with Toyota or the US brand v Japanese brands average either. But new US brand cars now are more reliable than new Toyota’s were years ago, and typically quite reliable compared to what older drivers like myself experienced decades ago.
The best source of car reliability data, CR’s, also tends to show (typically more complicated than usual) European luxury brands middle of the pack in reliability, tending more towards the top of the pack relatively recently. So no clear evidence there either that gadget/complication is enough of a factor in car reliability to stand out from all the other factors.
You’re fighting all the friction of the system. Your efficiency levels are lower. Gas engines have an optimally efficient power level. I’ve heard that this is “wide open throttle”, but this does not appear to be the case in my Prius. It seems to have a sweet spot that is at about 20% or 30% output that it wants to be in. I think it’s a thermodynamics thing - it takes time for the gas in the cylinders to fully combust and for the power stroke to fully extract the energy. Running the engine faster is less efficient, and the Prius engine is small, optimized for lower weight and the power levels needed for normal driving.
Anyways, this “barely turning over” thing is a feature in numerous GM vehicles. They do idle while only using some of the cylinders. Still nothing like the efficiency of a Prius.
Instead, my Prius will run in short bursts at a more efficient level and store the extra energy over that is needed at the moment in the battery. So in residential streets, stop and go traffic, or if I am just sitting in the car enjoying the A/C, the engine will start, run for 1-4 minutes, and then stop again. If you’re moving you can barely feel a judder though it is more obvious when stationary.
It absolutely is neat stuff. Of course, it’s basically obsolete - BEVs are superior in every single respect except for the cost of the battery. The Prius is just an intermediate product, like the B-36 bomber.
I bought my Prius recently, since the data says it’s one of the least expensive cars to maintain and it’s obviously very economical in fuel. Bought a 6 year old one, since that’s supposed to be the sweet spot on the depreciation curve between vehicle age and condition and cost, for 36% of what the original owner paid, while the vehicle has at least 66% of it’s mileage life remaining.