The thing that irriates me most is that it stops and re-starts straight away. Why in those conditions does it just not turn off at all. Very annoying. But only those of us who have experienced it will know what we're talking about

nemchenk said:

Exactly. And the car knows the outside temp, so if it is that it should really know not to engage S/S at all.

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no it doesn't, the dash knows the outside temp, not the engine control system. There is a difference.

Regarding fuel used to restart the engine, unless it's cold and on cold start cycle it doesn't use extra fuel to start it. If getting niggly there may be a very very small extra draw to recoupe the battery from the starting.

When you restart using S&S does it not rev higher than the usual idle speed (even momentarily)?

RobinPJ said:

My grandfather was a Major in the Royal Army Service Corps and an engineer and he used to say the same thing - turning your engine off and on uses more fuel than you save, for short periods.

This is probably less so with modern ECU controlled fuel injection systems where there is less of a spike in fuel usage as the engine starts, but there must come a point when it is not worth turning off.

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There was a discussion before on the amount of time that it takes to warrant turning your car off - I got the impression at the time that it was 60 seconds.

This link states 20 seconds but on the basis if you think it's going to be a minute.
When you turn on a car,it uses a bit of gas. When the car is idling, it uses a fixed amount of gasover a period of time (especially with the AC on).
In most scenarios (depending on the car), the energy balance will be positiveif you turn off your car for more then 20 seconds.
That means you can save gas if you turn off you car while waiting at longtraffic light sequences, railroad crossings or while your better half pullsmoney from the ATM. Any time you can foresee that you will not be moving formore then 30s or 1minute you should turn off the engine to help your vacation budget.

There would appear to be an intelligence problem with the S/S (on the 500) but if you look at some of the electronics that are available now it has a 'learning capability'. E.g the underfloor heating control units Devi (now owned by Danfoss) have a controller called Devi 550 which from experience knows when to kick start the heating so that it reaches the desired temperature. It does not work on first setting it but works on subsequent 'attempts'.

Most Easterly Pandas said:

no it doesn't, the dash knows the outside temp, not the engine control system. There is a difference.

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I do believe I said "car", not dash or ECU

Seems to me like a shortcoming of the 500's engine-management, whichever part(s) of the system are responsible.

So it would seem that if it is a cold day, we are best off shutting S/S down manually.

nemchenk said:

I do believe I said "car", not dash or ECU

Seems to me like a shortcoming of the 500's engine-management, whichever part(s) of the system are responsible.

So it would seem that if it is a cold day, we are best off shutting S/S down manually.

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"car" refers to the unit as a whole though does it not

Mercky said:

So how much fuel is actually saved by switching on and off the engine for 10 seconds? I'd say switching off and back on for that short a duration probably uses more fuel if anything! I would imagine there is a minimum duration under which has a nil or negative impact on fuel saving and I'd reckon that duration would be more then 9 or 10 seconds

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Most Easterly Pandas said:

Regarding fuel used to restart the engine, unless it's cold and on cold start cycle it doesn't use extra fuel to start it.

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You can't both be right!

I'm giving Mercky my vote on this one - I'd expect the ECU to overfuel the engine slightly when starting & the brief but noticeable increase in rpm when the engine restarts would tend to support this point of view - well done Robin for making the connection.

I'd love to know what the breakeven point is when the extra fuel needed to restart the engine & recharge the battery balances the savings made by stopping it - it's a question I've asked before.

In the absence of any proper evidence, I'd say Loveshandbags post is probably not far out - anything much less than 15-20 seconds & you'd be better off just letting it keep running.

I don't have any detailed knowledge of the sensors & algorithms actually used by the S/S system, but I think some of you may be crediting it with having more intelligence than it really has. It could just be done on battery voltage & current drain - and the low temperatures we're having just now will significantly affect battery performance, perhaps to the point where the voltage drops sufficiently to trigger a premature restart. But that's very much just another guess.

Whatever, as bgunn says, I'm sure the return to warmer weather will see a resumption of normal operation .

Most Easterly Pandas said:

"car" refers to the unit as a whole though does it not

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Indeed I'm just saying -- the data is there, available to be utilised.

nemchenk said:

Indeed I'm just saying -- the data is there, available to be utilised.

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It's not that straightforward. I would be out of software development since the mid 90s but the language used for 'formal programming' is different to 'Artifical Intelligence' situations. In University I specialised in Formal methods (have a M.Sc in it) but some of the guys in the class specialised in AI languages where a 'program' would acquire 'intelligence' in learning what's happened i.e. a knowledge base is built up. Sometimes it's not always possible to predict every eventuality so a standard language doesn't suit the application. I would guess that 'C' has been using for the programming judging by the skill set being looked for in new recruits in the 'Fiat' camp. This may be capable of partially minicking a AI setup but it may not be able to adapt to the 'real world' given the number of parameters that it would have to cater for.
http://www.magnetimarelli.com/english/index.php
http://www.linkedin.com/jobs/jobs-Software-Developer-2482502

The advice given in an earlier post to turn off the S/S in cold weather would appear to be the best one.
EDIT: just realised that you gave the advice.

Most Easterly Pandas said:

"car" refers to the unit as a whole though does it not

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The 'car' does know the outside temp though - think about where the instrument pack gets the outside temp reading from - it's on the CAN bus, so available to any CAN device in the car. Climate control needs to know the outside temp, as well as the engine management (for the fine control that EU5 demands), amongst other things..

bgunn said:

The 'car' does know the outside temp though - think about where the instrument pack gets the outside temp reading from - it's on the CAN bus, so available to any CAN device in the car. Climate control needs to know the outside temp, as well as the engine management (for the fine control that EU5 demands), amongst other things..

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I thought that it was only when you have the 'body coloured mirrors' that you got the outside temperature. So if you have a POP and you haven't specified that option there's no outside temperature on the instrument cluster. On the MiTo the Climate control uses a 'heat detector' - a plastic protrusion in the middle on the dash on the inside of the windscreen to determinate the effect of the sun rays as a factor in getting the settings right. Get the impression that there's no outside temperature 'feed' for the S/S.

Ok, so maybe not in Pop trim, but it is there.

I myself am a coder and now a dev manager, though I confess I've not written any C in 10 years now. Java, Python, PHP, and plenty of RAD, sure, but not hard-core C. I suppose in the kind of real-time application we are talking about here, C is probably still being used, but the speicifcs are somewhat irrelevant IMHO.

The data is there, everything else is just mechanics of getting it to the S/S system.

But anyway, we are getting a little off-topic

nemchenk said:

Ok, so maybe not in Pop trim, but it is there.

I myself am a coder and now a dev manager, though I confess I've not written any C in 10 years now. Java, Python, PHP, and plenty of RAD, sure, but not hard-core C. I suppose in the kind of real-time application we are talking about here, C is probably still being used, but the speicifcs are somewhat irrelevant IMHO.

The data is there, everything else is just mechanics of getting it to the S/S system.

But anyway, we are getting a little off-topic

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Looking at your skillset those languages are scripting ones (for web applications) and RAD would not be applicable to embedded system designs. I would not categorise 'C' as being hardcore and it doesn't need the mindset of a C++ developer nor even a functional language like LISP (used in AI) which despite been an 'old' language is still favoured. C is being used by 'Fiat' and IMHO specifics are relevant.

S/S on the 500 would have been developed to a particular budget and emission regulatory constraints. It would appear that the outside temperature has been left out of the 'logic' used in the 500 S/S. JR's posting where he referred to S/S only engaging when the temperature on the quarter way mark indicates that it's working off the Coolant temperature. If the outside temperature is included then the S/S would only work over a specified outside temperature which could exclude certain countries / times of the year and the 95grs/km may not be admissable.

Kia has re-looked at their 'logic' and have instructed their Engineers to tweek their systems. Their system is called Idle Stop and Go (ISG).
http://www.autoblog.com/2012/01/20/kia-start-stop-system-delayed-due-to-poor-feedback-from-media/

If you compare the effort put into Blue & Me which is being put forward as a key selling point of the 'Fiat' range, S/S is only one component of a much bigger picture. BMW had put a big effort in their systems developing a Micro Hybrid i.e. with re-generative braking & Absorption Glass Mat batteries (recent thread on the FF). It will interesting to see the wear & tear impacts on the 500 in another year or 2 with S/S.

Recently the MJ II 1.3 has had it's power reduced to 85bhp from 95bhp and has had S/S 'applied' to bring it below the 'magic' 100 grs/km - this will work it's way to the 500. I would question the logic on re-starting a diesel engine seen it takes more 'crank' to start than a petrol equivalent.

It's doubtful that S/S will ever get the efforts that has been put into other developments and having thought about it an AI approach it would be over the top. This has been reserved for collision avoidance systems and driverless cars. The only real world examples today I could find for this technology has been in relation to licence plate recognition for speeding offences. And even at that OCR is no longer categorised in the AI category and has been downranked.

Below I have made a weak attempt at trying to model the 'behaviour' of S/S system. We have been lucky before in getting an ex-Fiat 'expert' onto the FF within some inside knowledge. I can't see this logic being a 'trade' secret although for the Kia engineers their logic could become one. Wiki stated that the system used on the 500 was the Robert Bosch GmbH which appears different from the one developed on the MiTo range from Powertrain technologies. All that has been revealed is that 'several sensors and control strategies are employed to manage stop and restart operations' and that came this reference.

Personally I would prefer to have a 'STOP/START' button on the dash and do away with the ignition key (keyless entry) and use my own 'intelligence' to know when to KILL the engine. Some things are better off in the 'hands' of the driver. The Eco brigade could end up costing us more money in excessive wear and tear.

For a very small minority on the FF this might make a bit of sense so bear with me. I doubt that Fiat have a TOLERANCEOFFCONDITION are probably looping on the CANISWITCHOFF. If Fiat had their way now they might attempt a 'Clean sheet approach' and not just do a few tweeks as the Kia engineers are doing.

CARSTOPPED then CANISWITCHOFF
End

CANISWITCHOFF = true then KILL ENGINE
Repeat TOLERNANCEOFFCONDITION = false then CHECKAUTOSTART
End

CANISWITCHOFF
Coolant WARM otherwise FAIL
Battery ENOUGHCHARGE otherwise FAIL
Electrical NOTTOOMUCHDRAW otherwise FAIL
Return TRUE

TOLERANCEOFFCONDITION
Coolant WARMTOLERANT otherwise FAIL
Battery ENOUGHCHARGETOLERANCE otherwise FAIL
Electrical NOTTOOMUCHDRAWTOLERANCE otherwise FAIL
Return TRUE

CHECKAUTOSTART
Has seat belt dis-connected FAIL
Has the door opened FAIL
Has the ignition being Switched off FAIL
START engine

Seriously, PDL? I think we might bore the non--software-dev crowd!

nemchenk said:

I've kept the S/S off on my Twinair to reduce engine wear during the first 2K miles, but have now put it back on. And there seems to be a problem:

S/S shuts the engine down properly most times, but then the engine starts back up almost immediately.

Any ideas what could be causing this?

Many thanks in advance!

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Andy Monty said:

Dont just tell them to search Point them in the right direction! even if its just a link to the advanced search option with a bit of a welcome wouldn't go amiss

https://www.fiatforum.com/search.php

What will help even more Do a search for them and post them a couple of links from the search result to their problem. Along with the search link so you help them in the short term get the info they need and in future they can help themselves (that sounds like an Oxfam campaign doesn't it

)

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Above posting taken from a recent sticky. Here are one of the threads on 'Stop Start'...
https://www.fiatforum.com/500/268497-start-stop-stop-go-traffic.html
There might be an answer in one of them.

Yes, I read that thread -- didn't think there was an answer in there though

I'm still getting the "twitchy" S/S, even at ~11C. Come to think of it, I rented a 1.2 Lounge in Oct/Nov, and the S/S on that worked fine even in the cold snap we had back then which was ~0C.

So I don't think it's the outside temp, or not *just* that Might have to contact my dealer and see if they know anything about this kind of problem...

nemchenk said:

Yes, I read that thread -- didn't think there was an answer in there though

I'm still getting the "twitchy" S/S, even at ~11C. Come to think of it, I rented a 1.2 Lounge in Oct/Nov, and the S/S on that worked fine even in the cold snap we had back then which was ~0C.

So I don't think it's the outside temp, or not *just* that Might have to contact my dealer and see if they know anything about this kind of problem...

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TBH mine worked flawlessly right though the winter.

From some experience of helping out a friend who's had intermittent problems with theirs, and piecing together some of the other posts on this forum, I'd say the first thing to do is to make absolutely certain of the battery condition.

nemchenk said:

I'm still getting the "twitchy" S/S, even at ~11C. Come to think of it, I rented a 1.2 Lounge in Oct/Nov, and the S/S on that worked fine even in the cold snap we had back then which was ~0C.

So I don't think it's the outside temp, or not *just* that ...

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I found this quite interesting:

D4nny8oy said:

On the Stop/Start course it was stressed that the battery must have had a full charge before going out, otherwise the Intelligent Battery Sensor cannot monitor the battery condition accurately.

If it believes that the battery is at a level where it cannot be trusted to restart again if stopped, the Stop/Start will not work and the engine will remain running.

Remember that modern batteries do not receive a deep-enough charge from the alternator to fully top them up. If it's not 100% charged before it's fitted to the car, it's lifespan is reduced.

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Hmmm... that is interesting! Worth putting a charger on it overnight, do you think?

nemchenk said:

Hmmm... that is interesting! Worth putting a charger on it overnight, do you think?

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Certainly worth a try. Make sure you connect the charger correctly - positive to the battery terminal, negative to the remote battery post or (better) to a secure earth point on the chassis .

On no account connect a battery charger straight across the battery terminals to any car fitted with S/S - there's the possibility of damaging some expensive electronics. Read this post if in any doubt:

https://www.fiatforum.com/500/290590-flat-ish-battery.html?p=2935437