Should Auto-start-stop Be Affected By Interior Temperature Setting?

[quaffa]

Hi all.

I've got a bit of a puzzler here, or at least it's puzzling me! Can anyone enlighten me at all please?

We've had a 2013 Fiesta Titanium 1.0 litre EcoBoost since last April, and up until we took it into our local Ford dealer for a service in May this year, the Auto-Start-Stop feature worked most of the time. (I know it has it's quirks, and doesn't always activate, but I mean it activated on a fairly regular basis when the engine was warmed up.)

Since we had it serviced though, it has barely worked at all. We had a curious 'Engine Malfunction: service Now' warning message appear about a fortnight after it had been serviced, (and, as dictated by sod's law, the very moment we arrived on the south coast for a week's holiday), but upon re-starting the engine the 'amber spanner' icon was no longer lit and everything seemed to be working normally. Apart from the Auto-Stop-Start, that is, which didn't work for the rest of our holiday or for a while after it.

I took the car into our local dealer when we got back home, and they reckoned that the Auto-Start-Stop needed 're-setting', so I had to leave the car with them for a whole day for that to be done. This was on 17th June. The Auto-Start-Stop was duly re-set but, apparently despite 'extensive investigation', the reason why it had stopped working was not ascertained.

The Auto-Stop-Start then worked normally for two days... and then it stopped working again. The engine has not auto-stopped at all since 19th June, and we have the car booked in again for further investigation next month.

At no point in this story has the 'A' icon that always lights up briefly at engine-start been anything but green, even after the engine malfunction warning.

But here is the puzzle... This morning the weather was a bit chillier than it has been, and so I changed the interior temperature setting from Lo to 16.0, and immediately after changing that setting the engine began cutting out whenever I stopped and set the handbrake at traffic lights, and re-started as it should as soon as I dipped the clutch.

Why should changing the interior temperature setting in the car affect the Auto-Start-Stop system in this way? I could understand if we'd had the air conditioning switched on but, although the temperature setting has been Lo, the air con has been switched off most of the time, and certainly for at least the last fortnight or so.

I'm now wondering whether it is worth taking the car back in next month, because the Auto-Stop-Start seems to be working again.

[Stoney871]

I reckon condensation on a circuit somewhere due to the low interior temperature.

I had it happen once on a day when it was particularly hot and humid and aircon was at max chat.

[quaffa]

Thanks for that Clive but, as you imply, when you had the occurrence it was a hot & humid day. This morning it was cooler, and therefore less humid than if it were warmer. There was certainly no sign of any condensation on the windows or anything.

And of course, the problem with the Auto-Start-Stop has been current now for well over a month; it hasn't been affected by condensation for all that time.

Further developments to the problem this evening, when the Auto-Start-Stop failed to cut out the engine at all on the way back from work. (A thirty minute journey, so the engine has plenty of chance to warm-up.) So it looks like the underlying problem still hasn't gone away, and it was an anomaly that it worked this morning. Why it worked, and whether it had anything to do with the temperature setting change remains a mystery.

[Enduser]

I have just got a 2011 Focus with this Start/Stop feature. It has never worked. The Dealer checked it and said it was not working because the battery was less than 75% charged. According to the handbook there are about six different, designed, reasons why it will not work. Certain air con settings are one of them. This feature is, in my opion, is more trouble than it's worth. I am quite happy that it does not work on mine.

[quaffa]

Jim, You're absolutely right. I think it is probably more trouble than it's worth too. But I'm viewing it's lack of correct operation as a symptom of a potentially more serious issue rather than a problem in itself.

I want to know why it is not working, really, more than just getting it working again. And what is it that is now making it work for a while, and then stop working again?

When my Fiesta was in last month they checked the battery, because that was 'a theory', but the test revealed that the battery was 'over 95% charged' and they dismissed it as a possible cause. I have a sneaking feeling that it might be voltage regulator-related. Is something causing the voltage to drop somehow, which the system then interprets as an engine malfunction of some sort that causes the A.S.S. (just realised what the acronym is!!!) to fail to operate.

Or, is there an actual problem with the engine or software somewhere that could lead to something more serious?

[Incontro]

Jim, You're absolutely right. I think it is probably more trouble than it's worth too. But I'm viewing it's lack of correct operation as a symptom of a potentially more serious issue rather than a problem in itself.

I want to know why it is not working, really, more than just getting it working again. And what is it that is now making it work for a while, and then stop working again?

When my Fiesta was in last month they checked the battery, because that was 'a theory', but the test revealed that the battery was 'over 95% charged' and they dismissed it as a possible cause. I have a sneaking feeling that it might be voltage regulator-related. Is something causing the voltage to drop somehow, which the system then interprets as an engine malfunction of some sort that causes the A.S.S. (just realised what the acronym is!!!) to fail to operate.

Or, is there an actual problem with the engine or software somewhere that could lead to something more serious?

Try having climate control completely off (no A/C or no fan), and see if it helps. On nearly all cars, if the A/C is on, the compressor needs to run, which requires power from the engine. So on new cars that have start/stop functionality, the engine usually won't switch off when stationary, if the A/C is being used. I have experienced this with a lot of rental cars.

Hope that makes sense.

[quaffa]

Thanks Steve.

Yes, I'd guessed about the air-con preventing operation of the a.s.s. The thing is, though, that the problem with it not working at all was when the air-con was switched off.

I admit that I've not tried it without the fan on though, so I will give it a go and see what happens. At the present it seems to work okay for one journey once the engine is warmed up, but then it doesn't operate at all on the next one.

It's completely beating me. I'm wondering now whether there has been some sort of software corruption somewhere somehow.

[iantt]

Mines gone intermitant for a week, then all fine again now. No reason for it, I know its nothing more than state of battery charge, I think on mine it could be down to the way I been driving it recently( economically , low revs , coasting.55mpg) Alternater mainly charges on overrun , so ive not been slowing down from higher revs,

Back to normal driving and fine again now. May be just coincedence,

[quaffa]

Some progress, of sorts...

I followed Steve's advice from a couple of posts back and switched off the 'climate control' completely, so no fan at all, and the A.S.S. immediately began working again. I switched it back on again with the temperature setting back to 16.0°, and it continued working, then I switched the temperature back to Lo and the A.S.S. stopped working again. Switching off the radio also seems to have an effect on whether the A.S.S. operates. And for the first time these effects are reproducible.

So now I'm reasonably convinced that it is a voltage thing, even though when it was last in the local dealer tested the battery and reckoned it was 'perfect' with a 95% charge.

I think the correct answer to my original post is, or should be, simply 'No'. But what I've been finding is that in reality, with the present battery, it does.

It is strange that it worked perfectly for twelve months, whatever setting we had on the climate control, and then immediately after we had it serviced it started failing, but I reserve my judgement on that. At least I now have some evidence of what is causing it to fail.

Thanks everyone.

[iantt]

I hope its not 95% charged, that sounds wrong, too high, optimum is 80% it wants .more than that and it will actively discharge to 80 or there about.

[Enduser]

The first time i took the car back to the dealer to discover why the stop start was not working they said it was the battery. It's going back again next week to correct a paint defect and they are going to keep charge the battery overnight, which should, they say, fix the problem. I am with 'quaffa' I don't particularly want it but I do want to find out why it's not working.

It's interesting that it seems to be the A/C as I was given a techie handout on why the auto start stop may not work, as I said before the A/C was on the list, the reason being that if it was trying to maintain a high or low temperature the stop start may not operate. There were a number of other reasons.

I still think that it may be the battery as it's four years old, yes I know that they should last longer than that, but it depends on many things when it comes to batteries.

[quaffa]

I hope its not 95% charged, that sounds wrong, too high, optimum is 80% it wants .more than that and it will actively discharge to 80 or there about.

Well, of course I personally have no idea what it's charge was, but the phrase the dealer's engineer used was 'at 95% of perfect'. So I guess that he may have meant '95% of 80%', maybe?

My battery is still less than three years old at present, but I think I may ask for it to be replaced when it goes in. I doubt it will be covered by the warranty though.

[Preee]

My Stop/Start history :)

Mk3 Focus brought when a few months old 2012, Stop/Start worked once !!! the entire time I had it haha.

Brand New Mk3.5 Focus, never ever fails to work !, to the point where I switch the damn thing off or make sure I stay in gear, This week though I had Fan speed on high, it did not work, I reduced fan speed to speed 2 and the engine switched off.

But I know that in a few months time, with my short trips to work and back the battery will become low like my other Mk3, and i'm sure it will stop all together.

So, perhaps your battery has reached a condition where its peak performance has passed, and this is the probable reason its intermittent

[quaffa]

Ha! Should've read the manual more closely...

Look what I found on page 103:-

The system may not shut down the engine under certain conditions, for example:

• To maintain the interior climate. [My bold]

• Low battery voltage.

• The outside temperature is too low or too high.

• The driver's door has been opened.

• Low engine operating temperature.

• Low brake system vacuum.

• If a road speed of 3 mph (5 km/h) has not been exceeded.

• The driver's safety belt has not been fastened.

Although, to be fair, it did operate for twelve months without us switching off the fan, whereas now it only operates when we switch off the fan. I still suspect a voltage problem.

[jeebowhite]

goes to show the old adage of "Read The Flippin' Manual" has once again come to assist lol :p

Its amazing how many factors it takes into consideration though to stop the engine or not!

[Stoney871]

Basically ACS won't kick in unless the system is 100% sure that the car will restart every time.

Any electrical variations from optimal values will suspend it.

[jeebowhite]

I can kins of understand some of them, I mean things like seat belts you don't want to jump out thinking you have stopped the car for some begger to dive in, but things like low engine temp... Seems daft as I could start the car in minus 10, so why you whinging your only at 20 degrees, if you can start at minus ten then you should manage 20 lol

[iantt]

Low engine operating temp is set quite low to be honest, I can set off from home cold, do probably 200m at 30 and it will work as long as all other parameters are OK.

[Enduser]

Ha! Should've read the manual more closely...

Look what I found on page 103:-

The system may not shut down the engine under certain conditions, for example:

• To maintain the interior climate. [My bold]

• Low battery voltage.

• The outside temperature is too low or too high.

• The driver's door has been opened.

• Low engine operating temperature.

• Low brake system vacuum.

• If a road speed of 3 mph (5 km/h) has not been exceeded.

• The driver's safety belt has not been fastened.

Although, to be fair, it did operate for twelve months without us switching off the fan, whereas now it only operates when we switch off the fan. I still suspect a voltage problem.

Just back from the dealers after an overnight battery charge. During a short drive home SS was working as designd, even started itself having been stopped for a while to maintain a 19c temp as it was hot inside. I switched it off as there was a lot of stopping and going at T/L etc. When SS had stopped the engine a greem A symbol came up on the drivers display. So far so good.

[quaffa]

Well, just for info, I took my Fiesta in to the local dealership the other day and when I collected it I was told that a 'software update' had been applied, and that it was this software update that was required in order to restore the A.S.S. functionality. I can report that the feature was working again from when I collected it, and it has now been working correctly for a full week, even when we have the interior fan on. (Indeed, it has even operated when we've had the air conditioning on once, which I hadn't expected.)

I'm not sure whether I wasn't just being BSed though, because of course it worked correctly for twelve months until June this year without the software update, so why did it need one now?

I made the point that I'd not been made aware of the vehicle needing a software update, and asked why, as the vehicle owner, there wasn't some sort of flag-up on the display screen or something. There followed a long rambling waffle which made little sense to me at the time, and still doesn't. The jist of it was 'it's not like a software update on your computer or mobile phone', and while I made the point that in fact a software update is a software update, no matter what it's for, I could tell I wasn't getting anywhere near breaching the BS screen, and I gave up.

[Paul Loseby]

This was what the brochure said.  I bought the car new at the beginning of July 2018.  They've changed the battery once and it still doesn't work.  If Ford advertise it, then I expect to have it working.  I paid for it.

[iantt]

can you enlighten us on your journey lengths and frequency. also does the stop start button iluminate  at all? what made the garage change the battery? a guess? 

[Guest]

After reading through these posts as I have had the same problem of stop/start  being intermittent. I yesterday made the long journey from Somerset to North Yorkshire giving the battery a good charge on the way. The stop start is now working perfectly well. So it seems to be a low voltage issue affecting this. My drive to work every day is five miles each way between Street and Glastonbury. Obviously not far enough to properly charge the battery.

[Mark M]

If the battery voltage is too low it won't work.

If you have the climate set to a relatively cold temperature it will try to achieve this by having the aircon running, which will obviously stop it working.

If the engine temperature is too low it won't work.

 

There's a whole host of reasons why stop/start will stop working but they seem to be the main 3 from experience.