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Hagerty
Hagerty Employee

Piston Slap: Concluding commencements regarding Stop/Start technology?

I am wondering about the newer cars that turn off when they stop at a light. Is this bad for the car overall? Sajeev answers: I think the short answer to this question is a solid "not really."
https://www.hagerty.com/media/maintenance-and-tech/piston-slap-concluding-commencements-regarding-st...
24 REPLIES 24
olde_blue
Pit Crew

What about the wear on the electric starter itself? For the average driver, a start/stop starter I would guess is engaged at least 20 to 60 times more often than an idling vehicle. The last starter I replaced had 25 years and over 200k miles on it, and was relatively easy to get to. Even if modern starters are 10 times more durable it would have failed sooner with start/stop. I have heard that in some vehicles (some VWs in particular) require the engine to be pulled to get to the starter. In the long run, the fuel savings might not be worth it.
audiocage
Advanced Driver

Having the engine shut off when you stop at a light isn't anything new. I had a '72 Polara that would do that...
Bavarian
Pit Crew

You know, Starters/Alternators and batteries had to be upgraded, and then battery became an AGM unit, all adding to the costs. Some , at least on BMW products, have alleged that that premature rod bearing wear could be attributed to this, as we have variable displacement oil pumps. Now mild hybrid units are using the power unit in the bell housing to act as the starter and alternator. This complexity will come at quite a cost.Initially, we were quoted a very small advantage to CAFE ratings. I am not sure if you can shut the feature off on the newest cars, but you can on BMW recently.
TG
Gearhead

My neighbor shuts the one off in his Toyota
hyperv6
Collector

Let’s just keep this simple Sanjeev did a great job here but I just want to cut to the basics as most miss the fine points.

#1 No it does not hurt the engine at all.

#2 it is made to only work at low load cases like when it is up to temp, not when AC is on high and or if the weather is very cold.

#3 Does it really save fuel? On paper yes but in the real world not really. It actually provides off cycle credits from the EPA that count to emissions numbers and fuel mileage numbers of a new car. Off cycle credits are for things difficult to measure.

The truth is it is a credit like they get for some paints, glass and low resistant alternators. automakers need these so they can keep these larger engines available to you.

The only liability may be a failure of an additional parts added for it. I really have not seen much of that.

I have found if you stop light and smooth in the GM system it will not shut off. But I also have a button to kill it too.

The only place mine shuts off much is city drive light to light. It is not really a big deal. Some days I kill it other I don’t even notice it.

The Cylinder drop is also another off cycle credit and in the real world saves little gas. I think they consider it more an emissions deal.

It is stuff like this that makes EV cars almost appealing as this is making most ICE much more expensive and complicated.
BMD4800
Engineer

It s@*cks in Phoenix.

Engine shuts off, A/C starts getting warmer, then it starts again, takes a while to be cold. Over certain ambient temps it won’t shut off, so that’s nice when it is 110. Still, I hate it. I have a delete kit to override it, but the thing is such hot garbage, I’m getting used to going through the pre-departure check list. Kind of like flying or driving a Model A.

Cylinder deactivation does work and is worth it. Granted, I deleted it with software, but before I did there was a significant difference on highways.

I absolutely HATE the idle shut down. Sometimes I need it to idle with the A/C running. But, it shuts down after a preset time.
DaveA
Instructor

Systems like this (and cylinder deactivation) may only save a little gas here and there, but it adds up. Modern Subarus keep track of how just how much fuel is saved by the auto start/stop feature. On a friends car it showed 1.6 gallons were saved over the last 3,800 miles. Assuming this rate continues, he’d save 42 gallons of gas by the time the car reaches 100,000 miles.

While this may not sound like a lot, imagine if every car in America could achieve this. According to some sources, there are 276 million vehicles in the US, of which approximately 108 million are cars. If every one of those cars could save 42 gallons of gas over the course of driving 100,000 miles, that would be approximately 4,536,000,000 gallons of gas saved. Heck, even if just 1/3 of vehicles could achieve this we’re still talking 1,496,880,000 gallons of gas.

THIS is why these technologies are such a big deal despite the small fuel savings some people tend to complain about. It’s a cumulative effect. It’s about millions of cars each making a small contribution, and it adds up fast.
Hagerty Fan
Not applicable

Bah, humbug.

I think that a more-effective use of this technology would be to switch that to a Start-Burnout-Stop-Burnout technology, where the system activates after you come to a stop, and immediately begins a massive power-brake burnout until the light changes back to green.

BMD4800
Engineer

Sometimes I activate the remote start to make Greenland more inhabitable.
Hagerty Fan
Not applicable

Why stop there? Activate two remote starts so speedboat races can finally be held on any point on or around the North Pole, and Antarctica can finally become the shorts-only vacation destination that it was always meant to be.

Wait, was that 'habitable', or 'inhabitable'?

TG
Gearhead

I have probably spilled more than 42 gallons filling up a car over 100,000 miles. These are the kind of numbers that make managers happy but that don't amount to much net change in the overall situation

Any vehicle I am in that has it I turn it off. I find the stumble on is just annoying.
Hagerty Fan
Not applicable

My question? How much cost has this technology added to the price of a vehicle?

DaveA
Instructor

I would think that the cost is small, especially considering the cost of required systems such as airbags and soon-to-be required systems such as Automatic Emergency Braking. Both are complex systems, but innovation and safety come at a price.

TG
Gearhead

and price usually comes with an associated carbon footprint

BMD4800
Engineer

I have lots of trees on my ranch. 

Snailish
Engineer

Hopefully less than 84 gallons of gas over 200 000 miles  ---or so I hear.

BMD4800
Engineer

And yet I can’t get a cassette deck.
hyperv6
Collector

Yes these systems are more Rube Goldberg in action. The saving in MPH and emissions are small. They are so small and inconsistent they have to resort to the Off Cycle Credit vs posting real numbers. 

 

Everyone wonders why Automakers are moving to BEV. Well it is due to the regulations that are getting damn near impossible to meet. 

 

These systems all add up to more and more cost as does the creation of turbo systems and smaller engines to meet these numbers. Keep in mind a engine program can be in the billions of dollars and even that engine may not be legal in 10 years. 

 

You can only cut so many cylinders and shrink cars in size or use only so many exotic light materials to build a car. We are nearing $50K average on ICE vehicles as the price of EV model have dropped much over the last 10 years. 

 

The automakers have looked at any and all options and the EV is the only one practical now and able to be made more affordable as more are built. 

 

They are just looking to survive in a very unfriendly political oversight era. 

 

Folks the automakers are just flat running out of tricks. This is why you see several MFGs getting caught cheating on Emissions. Yes they are that desperate. 

 

 

js100
Detailer

A very accurate summary! Political drivers vs. real world drivers backfire in the final application. All of these expensive when new systems are very, very expensive for the eventual owner of a high-mileage used car. I have the luxury of buying new cars, with warranties, but I truly pity the literal poor man who will have to keep these technical systems operational in the future. I picture a dystopian sci-fi scene where an underground garage installs illegal (politics again) devices to keep these ICE cars running for the huddled masses. (Rob, this is your cue for a future version of Hack Mechanic)
BMD4800
Engineer

Gasoline is a byproduct of refining.

The most cost effective method of disposal is transportation.

No ICEs, big costs in hydrogen cracking and producing lower profit derivatives. They won’t ban ICEs, they will incentivize BEVs as a means of control.
BMD4800
Engineer

They way to survive in an unsavory political environment is to not comply and tell your customers what’s up.

You don’t want a turbo 4 cyl in your full sized truck? Don’t blame us, blame these people and list names.

Meanwhile…enjoy your barbecues. Those are next.

Trust me.
BMD4800
Engineer

The fuel economy chasing is getting insane.

A/C shuts off with the engine, hot outside, fine, 2-foot drive this 0.5 L turbo charged turd bucket. Sorry it is hot outside, we saved 6 oz of fuel!
MustangJim
Technician

I have this in my 21 explorer. I've tried it, the fuel mileage savings is hardly noticeable but my annoyance of it is very noticeable. There is a little button on the center console right behind the e brake button. I'm in the habit of using my e brake and now I'm in the habit of pressing both when I start the car. Yes, when activated the operation is seem less, it works as it should, I just don't like it. All that stuff is added just so they can meet the Corp. Fuel economy standard and adds cost to our cars. Then they wonder why cars are so expensive.