Engine Stop / Start

[Martin-GTi]

I’ve been wondering about engine stop / start technology and whether the small fuel savings justify the potential wear on the engine.

I have to confess that my current car (and previous cars) haven’t had this option, but with the imminent delivery of my new Polo (I hope!) I wanted to see how people use this. I’ve always thought starting a car causes the most wear as the oil isn’t there to prevent metal-on-metal friction. I appreciate modern starter motors and batteries are robust enough to handle many times more engine starts, but do the pros outweigh the cons? Or are there few / no cons?

I found this article that seemed interesting, but what do others think?

https://www.autoevolution.com/news/the- ... 08734.html

[Andy Beats]

I was speaking to a mate who's just bought a Mazda 2 and the Mazda sales guy claims their stop/start doesn't use the starter motor.
Their's works by making sure one of the pistons is at the top of the stroke when the engine stops and then injecting/igniting a small amount of fuel into that cylinder when you want to re-start
That piston being pushed down then starts the whole engine rotating again.
If it's true, very clever and saves on starter motor wear.

[Griff74]

I have disabled the stop\start in my current Leon with OBDEleven, will do the same with my Polo once I've had it a few weeks to make sure it is all ok, is not out of worry for wearing out components too much (I know people with cars that have done 100k+ miles with it enabled and no issues), I do it just cos I hate the way it works with a DSG box.

[Andy Beats]

I have disabled the stop\start in my current Leon with OBDEleven, will do the same with my Polo once I've had it a few weeks to make sure it is all ok, is not out of worry for wearing out components too much (I know people with cars that have done 100k+ miles with it enabled and no issues), I do it just cos I hate the way it works with a DSG box.

If you find out a way to disable all the anti-collision crap, can you let me know?
I'd happily drive the length of the country to have that disabled.

[MattHGR]

Yes Mazda do have this feature.
Also a smoother startup compared to other start stop vehicles as the first piston ignition is less powerful than a starter motor start.
Very clever stuff.


My Opinion:
I don't think start stop wear should be a worry in terms of oil flow, as once the engine is warm, the oil will still be there for a few minutes anyway.
It's the battery / starter that MAY show signs of wear later in life

Thanks

[Andy Beats]

I agree that there's more than enough oil floating about an engine for stop/start not to cause any wear.
It's funny that people will consider this a concern, but will leave their car for two weeks while they go on holiday and not give a thought to starting it.

[steeve]

If the car is a turbo then I'll always disable stop start. Starter motors and engine bearings all updated for stop start. But it's the turbo bearings that are most at risk.

[Andy Beats]

If the car is a turbo then I'll always disable stop start. Starter motors and engine bearings all updated for stop start. But it's the turbo bearings that are most at risk.

They have that covered now.
The S/S will only activate if the engine and turbo are below a certain RPM etc.
I've been on umpteen car forums over the years, I've owned a lot of different cars, and I've personally not seen a single post about turbo bearing failure being attributed to S/S.

[fazzy]

Since I'm still waiting for my Polo, I cannot say how this is taken care of by VW.
My previous car, the F20 1-series had a electric oil pump, which continues to circulate the oil, after the engine has stopped, so no worries about the turbo. Call it a turbo timer without the need for running the engine. I can only presume that VW has something similar.

As far as the battery is concerned, the battery actually loves the start-stop system... Your car battery doesn't like if you would drain it totally, but partial drain and then "top-up" is what car batteries love the most

End of the day, the only reason the start-stop system is there is so that the manufacturers meet the emission standards. Your car, while idling, consumes literally drops of fuel, so for the average motorist there will be no saving, but since the emission test consist of almost 50% time at idle, the emission gains are quite substantial and all looks fantastic on paper.
So there you have it.
Bullsh**t system to make you think you take care of the environment and save fuel.... Switch off as soon as possible.

[monkeyhanger]

^ Stop start does make a difference - but that difference is not huge, and depends on how long you are idle on your commute. It translates to about 5% saving for me when my route is congested, and about 2% when the roads are quieter in the school holidays.

NEDC had 26% of the cycle at a standstill, not half. Your post reminds me of an Aussie car facts blogger ranting about the tech.

Stop start can make a difference if you do face stops due to traffic on your journey, but the effects on mpg are massively oversold for almost everyone that doesn't do all of their driving in central London/Birmingham/Manchester.

Wear once the engine components are wetted with oil after initial start up is extremely low when compared to initial start up, and stop/start monitoring parameters stop the car shutting down if the turbo is overly hot or still spinning at high speed.

[fazzy]

The professor has spoken, I guess everybody must shut up....

[peeceeuk]

Didn't use the term "tramping" this time though.

[Andy Beats]

I think S/S must make a big difference to air quality in towns.
Walking into our town the other (cold) day, I went past a lengthy queue of traffic.
I noticed there wasn't the plumes of exhaust fumes you'd have seen years ago, and it wasn't an exercise in holding your breath as you walked past.

[vc-10]

Stop/start definitely makes a difference in my driving- but I'm mostly driving in congested Manchester! I've also noticed that sometimes the car will wait a second at idle before stopping- both my previous Fabia 1.2 TSI and current Ibiza 1.0 TSI do this. I wonder if this is to let the turbo spool down?

[Andy Beats]

I wonder if this is to let the turbo spool down?

Precisely what it's for, and why another member here (I forget who) was wrong to assume S/S damaged the turbo.
My BIL's Audi A6 Taxi - 184000 miles with no problems before he sold it (my god what a bargain that car would have been for the paltry £7k he got for it).
His Kia Estate - 100000 miles with no problems so far.
Taxis here aren't allowed to switch off their S/S and the public is encouraged to report any drivers they see doing it.