Stop start: the case for.

[anon]

Once a car is stationary as it far too often is, it becomes nothing more than a pollution machine. Not just gas but noise, too. The current stop start systems are being refined to cut the engine at coast down from 15 mph but those in the Ecoboost are only active at standstill.

Or not if you listen to the many doom mongers who think it is a waste of parts.

There are many reports of the system failing to work but nobody  seems to spend any money fixing the car because nothing is actually broken.

Why does it apparently malfunction?

Temperature. The engine needs to be warm enough. Not fully up to temperature but not stone cold. If your mission profile is half a mile to work and back, you will never get there.

 At the other end of the scale, the cooling fan continues to run if a very hot engine is switched off because the temperature will continue to rise so the fan cools the coolant which keeps it circulating until thethermostat closes at which point the engine is safe from overheating. The stop start is inhibited.

A big electrical load on a cold morning such as the heating of the windows,  the wipers lights and heater fan will be prioritised over stop start. The battery can only supply so much current. It is quite deliberately only charged by a fiendishly complicated algorithm to 80 % of its total capacity in order to maximise its life by a system that turns the alternator on and off according to the amount of energy taken from the battery. This is the fully charged point. A properly charged battery is essential for the stop start to work and the lack of it is responsible for the vast majority of perceived faults. If you were to take the car to a Ford dealer for an overnight charge, it comes back working. 

Regular long runs seem to be necessary to keep the battery fully charged and if you don't do them then the battery will need a top up charge from time to time.

This battery needs to be charged slightly differently to those you may have encountered in the past. Logically, there are fewer charging losses if you connect directly to the battery but here in the 21st century you connect the negative lead of the charger to the body Shell at the lug where the cable from the battery is bolted to the car. This is because there is a resistor in this lead and when charging, a tiny voltage is developed across this which tells the computer how much energy has been put back in. Without it, you're wasting your time. Some people use solar chargers for a top up which is ok for cars parked outside.

Settings> information> stop start>ok will explain why the engine is not stopping. 

Engine on due to heating/ cooling. Try turning the heating system off by pressing the right hand heater control.

Driver's seatbelt undone inhibits the system but the most common message will be engine on due to vehicle charging.

If you have the opportunity to drive the car a couple of hundred miles, the system will come back to life, probably a couple of journeys later as it learns the battery parameters when you think it is asleep so don't expect an instant result. This is why Ford charge overnight. They leave the car to think about it once it has been recharged

If the fuel level drops really low there is a risk that the pump in the tank will not pull up fuel fast enough for the system to respond so the system needs fuel and will then operate  It won't tell you about this as you have already been told that you are low on fuel.

Real faults elsewhere in the car can cause the system not to respond. The ABS signals from the wheels tell the car it is moving. Any fault here and the stop start fails safe.

You can turn it off if you really want to but most of what causes all the head scratching is perfectly normal operation. Understand what to expect from your stop start system and you will find it a good servant.

[Luke4efc]

37 minutes ago, anon said:

Or not if you listen to the many doom mongers who think it is a waste of parts.

Which it is. Switching off an engine the size of an A4 piece of paper for 30 seconds isn't going to make a blind bit of difference to overall emissions.

Infact, the emissions generated from manufacturing all these extra parts is probably more than you'll ever save by utilising stop/start. 

[alexp999]

It uses about 7s of idling fuel to restart an engine. So if it’s off for more than 7s you are saving fuel. With the mild hybrids it’s even easier to stop and restart the engine. 

[Marlburian]

1 hour ago, anon said:

... This battery needs to be charged slightly differently to those you may have encountered in the past. Logically, there are fewer charging losses if you connect directly to the battery but here in the 21st century you connect the negative lead of the charger to the body shell at the lug where the cable from the battery is bolted to the car. This is because there is a resistor in this lead and when charging, a tiny voltage is developed across this which tells the computer how much energy has been put back in. Without it, you're wasting your time. Some people use solar chargers for a top up which is ok for cars parked outside...

Oh dear, I'm confused. I've seen other advice saying that it's OK to connect a trickle charger to the negative lead.

I'm still assessing how best to use stop/start. Can't say I'm keen on using it every few minutes in urban driving, but I've always been one to turn off a conventional engine if I'm likely to be delayed for more than a minute. (A couple of my regular routes go across canal swing-bridges, where there can be delays of up to eight minutes).

EDIT: just checked the manual and it confirms what Anon wrote.

[anon]

Then you will find it useful. If I wanted to win the traffic light Grand Prix, I would choose something a bit quicker than a 100 HP as everybody else in this town drives a Maserati Levante, (probably while nanny is waiting for the Tesla charger to become free.) For that reason I don't mind the shutdown in queues of traffic. I can always keep my foot on the clutch or disengage the system if it became a problem.

This week the drive was only half a mile each way .Full Aircon, max defrost every morning and then the bootlid open most of the day in order to test a theory about gas struts. When I drove today  the stop start was greyed out. The display told me that the car was charging. Two key cycles later after about a total five mile run it was all as it should have been.

[anon]

All what parts? Uprated brushes and bearings in a starter motor and a larger battery both of which last longer as a result. Everything else from the speed sensors in the ABS to the clutch pedal switch is already there as are the sensors for temperature, battery load and charge level, fuel level etc. The car produces a lot of data in use. A subset of this data is used to work switches that are also already there. Stop start is easy and very cheap to implement, far, far more so than an added mild hybrid system.

[Tizer]

35 minutes ago, alexp999 said:

It uses about 7s of idling fuel to restart an engine. So if it’s off for more than 7s you are saving fuel. With the mild hybrids it’s even easier to stop and restart the engine. 

I don't know where you got that figure from Alex or how scientific the test was , but I would think that it does not tell the whole story because it does take into account the fuel and consequent emissions that are required to put the large amount of charge (easily a constant 20 Amps with lights, Heater Blower etc on) plus the large surge to start the car. These power draws will be non-linear and variable hence my scepticism.

2 hours ago, anon said:

If the fuel level drops really low there is a risk that the pump in the tank will not pull up fuel fast enough for the system to respond so the system needs fuel and will then operate

That is not true Brenda. The  Returnless Fuel system in my and most other modern cars does not dump Fuel Pressure because it can't. In cars such Diesels all the pressure is not dumped when switched off, and even if it was then the Ford Engineers would not be stupid enough to command the car to dump Fuel Pressure when S/S was activated.  

[anon]

Taking your points in order. The stop start system does not require a constant 20 amp charge. Complete fiction Tizer. Finger in the air guesswork to try and push a point that you simply cannot substantiate. Your second misses the point that the system will not work when the fuel level is very low to avoid the possibility that the car will not be able to restart due to fuel starvation.

[anon]

The original post was made to inform and educate those who were not aware of some of the subtleties of the system to help them get the best out of it rather than to promote a full on trollfest from the usual suspects. You can always turn it off.

[alexp999]

 

[anon]

Taking Alex's assertion of seven seconds idling fuel per start: 4.55 litres per gallon.

Display shows minimum idle consumption of 0.1 Gal/ HR . 455 ml. Divide by 3600 and multiply by seven. 884 microlitres. About a quarter of a millilitre of fuel per cylinder. Plenty enough extra to effect a start as about a ten per cent enrichment  works well enough so that must cover the recharging energy as well. The numbers tally.

[Paulkp]

Not sure about all the technical stuff above, but being a cynic who is aware of how manufacturers might set up the car to only reduce emissions during the test cycle, and not in real driving, and that the cycle I think includes a total of about 2 minutes stopped in a 20 minute test cycle, it might just be a good wheeze....

And when I see parked "new" cars idling just to charge the 'phone or run the air con., or "stop-starting" during a parking manoeuvre at Waitrose, it just makes me wonder ?

[Luke4efc]

1 hour ago, anon said:

Stop start is easy and very cheap to implement, far, far more so than an added mild hybrid system.

Apart from the fact you've had to write war on peace on how it works and the various components that can stop it working...

1 hour ago, anon said:

Display shows minimum idle consumption of 0.1 Gal/ HR . 455 ml.

This also proves how little fuel the engine uses when idling, and how it costs more to implement compared to the savings made. 7ml whilst sat at a set of lights for 1 minute isn't going to make a dent on your fuel consumption.

[Tizer]

1 hour ago, anon said:

The stop start system does not require a constant 20 amp charge. Complete fiction Tizer.

I never said that it did Brenda. What I said was that the car can easily be drawing 20 Amps from the battery when it is stopped, which needs to be replenished quickly as well as the draw from starting it again. That uses Fuel and leads to emissions.

1 hour ago, anon said:

Your second misses the point that the system will not work when the fuel level is very low to avoid the possibility that the car will not be able to restart due to fuel starvation.

A fully primed Fuel System will start a car whether the tank is full or not so full. You will only get Fuel Starvation if there is no fuel to draw out of the tank.

[Tizer]

1 hour ago, alexp999 said:

 

Thanks Alex. I had seen the other videos that he was referring to as well and they were not very scientific, they did not take into account the extra fuel used to recharge the battery.

[Marlburian]

4 hours ago, anon said:

The original post was made to inform and educate those who were not aware of some of the subtleties of the system to help them get the best out of it rather than to promote a full on trollfest from the usual suspects. You can always turn it off.

Not sure that it was trolling, just contributions to the discussion. (But as a newbie I've yet to become familiar with the personalities of regular contributors.)

3 hours ago, Paulkp said:

... And when I see parked "new" cars idling just to charge the 'phone or run the air con., or "stop-starting" during a parking manoeuvre at Waitrose, it just makes me wonder ?

One of my pet hates. The other Monday there were long delays in Culham, near Abingdon, because of a cycle race and filming for Steven Spielberg's latest film. I walked past rather too many cars with their engines ticking over. Not as if it was a chilly day.

2 hours ago, Luke4efc said:

Apart from the fact you've had to write war on peace on how it works and the various components that can stop it working...

I found Brenda's "epic" well written and useful. Early in my ownership of a Fiesta, I wondered about stop/start, did some Googling and had discovered more or less what she wrote. (Pity it it didn't appear a week ago🙂.)

[Marky146]

I must say town work is so much better in our Nissan Leaf than in my Fiesta. Or anything else I've tried. It actually can sit there with Air Con, phone charging and heated seats on and uses a quarter of f**k all of charge while doing it. We only get 60 usable miles out of it, a first gen 2016 24kwh car but it' perfect except for one thing. If we charge it fully, the regen doesn't work until it's below 94%. You can't select a lower charge limit and we live up a hill. Small problem..... Oh, and it doesn't appear to be depreciating at all... Sweet. Goes like a rocket from the lights too. Can hold it's own against my ST, until 30 at least. 

[Wino]

Let's not forget or over look the big black button on the dash near the steering wheel...... It say push to start and push to stop.

If your that bothered about the S/S not working the press the ***** button 👍

[Mavroz]

Some probably won't be happy but Auto Start / Stop isn't high on my priority of equipment on a car as say the auto door edge protectors.😁 Rarely take the car out of gear at lights and if I do, I turn the feature off for the rest of the journey.

Oh and yes, many times I do sit with the ignition on, when it is warm for the aircon and when it is gloomy or rainy to keep the front screen mist free..... The only annoying thing is when the car decides it wants to turn itself off "to save battery", i have to press the engine start stop to over ride it.👍🏻

[Paulkp]

On 10/17/2021 at 1:56 PM, anon said:

Display shows minimum idle consumption of 0.1 Gal/ HR .

Not having any gizmos like this on my Sierra, what is the resolution of the display ?

eg will it say 0.05 Gal/Hr?

or 0.15 Gal/Hr ?

[ArchAlf]

Currently have Ford looking into why my 2017 plate ST Line’ s SS worked perfectly but my 2020 NEVER works - apart from the first couple of days after my Ford Garage have ‘topped’ it up! (Driving habits haven’t changed) Also annoying as Ford Pass through my phone won’t work to lock/unlock car, when it goes into deep sleep to conserve battery!! Garage reckoned it needed at least 78% charge to make SS work?! 😡

[unofix]

Hi @ArchAlf, take a look at the thread on the "Mk 8 battery monitoring reset" , and a couple of youtube videos on there. It may give you some pointers as to why S/S often does not work as expected.

[Paulius55]

Never mind the stop/start not working. You will probably find that the front heated screen does not work either when the BMS determines that the battery charge is too low. As it is more likely to be low in winter then the chance of the screen clearing is slim. 

[cjay1]

On 10/18/2021 at 10:40 PM, ArchAlf said:

Currently have Ford looking into why my 2017 plate ST Line’ s SS worked perfectly but my 2020 NEVER works - apart from the first couple of days after my Ford Garage have ‘topped’ it up! (Driving habits haven’t changed) Also annoying as Ford Pass through my phone won’t work to lock/unlock car, when it goes into deep sleep to conserve battery!! Garage reckoned it needed at least 78% charge to make SS work?! 😡

I had a fault where the car only charged it self for a few minutes regardless of soc. Then from around 15 minutes in would not charge. then 10 minutes after start to discharge the battery at a rate of 1-2 amps. On occasion it got so low the car started to miss fire,trip codes, lights on the dash and switch radio off to save battery. 3 times it went to ford who put it on charge and tested the system and said no fault found. Went back a 4 time with forscan data from a long journey. Finally they diagnosed a faulty sensor and bad software that there was an update for.