Technical Start&Stop in stop-and-go traffic

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Technical Start&Stop in stop-and-go traffic

Mondaugen

2015 Twinair 105
Joined
Jul 21, 2010
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158
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Location
Germany
Hi guys,

I have a 500 1.2 Lounge (bought new in July 2010) with Start&Stop (S/S). According to the Fiat 500 manual, the S/S isn’t supposed to kick in unless the car has accelerated to ~6mph; cf. p.63:

Note The engine can only be stopped automatically after a speed of about 10 Km/h is reached, to prevent the engine from being repeatedly stopped when driving at walking pace.

However, mine cuts the engine every time I come to a halt, which is quite annoying in stop-and-go traffic when I definitely stay below 6mph. The dealer has installed the latest software and gave me a shrug.

Sure, I can turn S/S off manually, but I’m wondering how it behaves with other peoples’ cars in this case.

Cheers,

Lambert
 
Thats normal, mine does it too. If i stop the engine cuts, then if i role to 6mph the engine starts up again. :)

If it gets annoying just turn the start-stop off while in traffic.
 
I normally choose when to use stop-start - if I'm in a traffic jam I keep my foot on the clutch, if I'm at the back of a queue at lights I'll put it in neutral and let the engine stop.

Never bothered with the disable button
 
i am facing a serious problem with "start & stop" function while i m stopping at the hill then driving up a hill or slope. the car will roll back badly when the "star & stop" is running... it is scary and dangerous :( may i know anybody is facing the same issue?
 
i am facing a serious problem with "start & stop" function while i m stopping at the hill then driving up a hill or slope. the car will roll back badly when the "star & stop" is running... it is scary and dangerous :( may i know anybody is facing the same issue?

i don't know if you have hillholder but it's quite serious if it doesn't work when S/S is active. if you don't have it, there's not much to do but to use handbrake as rallycinq mentioned (or just disable it manually). maybe next gen S/S will have built-in accelerometer to sense incline and disable itself automatically, unless hillholder comes as standart of course. :)
 
i don't know if you have hillholder but it's quite serious if it doesn't work when S/S is active. if you don't have it, there's not much to do but to use handbrake as rallycinq mentioned (or just disable it manually). maybe next gen S/S will have built-in accelerometer to sense incline and disable itself automatically, unless hillholder comes as standart of course. :)

I think the hillholder only comes with the ASR - this is standard with the 1.4 but is optional extra on the rest of the models and it's priced reasonably.
 
i am facing a serious problem with "start & stop" function while i m stopping at the hill then driving up a hill or slope. the car will roll back badly when the "star & stop" is running... it is scary and dangerous :( may i know anybody is facing the same issue?

This is not an issue with start stop. EVERY car will role back when the engine is off on a hill. Use the handbrake. :bang:
 
i am facing a serious problem with "start & stop" function while i m stopping at the hill then driving up a hill or slope. the car will roll back badly when the "star & stop" is running... it is scary and dangerous :( may i know anybody is facing the same issue?

Do you have a manual transmission? S&S only kicks in when you're in neutral so shouldn't affect hill starts.

How does S&S work in an auto? Do you have to put it in park?
 
Questions in post 1# are interesting can I ask the technically minded;

1) what harm can be done to the starter & engine with SS kicking in every 20 - 30 seconds ?

I know from reading Bosch bumph that the starter and Battery are heavy duty and if the Battery was to go low SS would disable.

2) what harm can be done to the Clutch if the clutch is kept pressed in for a minute at a time in SS traffic ?

Thanks
 
Questions in post 1# are interesting can I ask the technically minded;

1) what harm can be done to the starter & engine with SS kicking in every 20 - 30 seconds ?

I know from reading Bosch bumph that the starter and Battery are heavy duty and if the Battery was to go low SS would disable.

2) what harm can be done to the Clutch if the clutch is kept pressed in for a minute at a time in SS traffic ?

Thanks

1. Some extra wear on the starter & soleniod, though as you say these components should have been 'beefed up' to compensate. Another issue which actually concerns me more is that the fuel management system probably injects a little extra fuel when starting the engine, and this excess fuel could wash oil off the bores & pass unburnt into the catalytic converter - both things you don't want to happen. Also this could actually mean you end up using more fuel, not less, if the engine is continually restarting within a few seconds of it stopping. I'd be really interested to know the 'break-even' time when the fuel saved from stopping the engine idling equals the extra fuel needed to restart it.

2. If the clutch pedal is fully depressed then there shouldn't be any clutch drag & the only component subjected to extra wear will be the clutch release bearing. These can and do fail & it will be interesting to see how many high mileage S/S cars develop a rattle when the clutch is engaged.

I like having S/S & miss it on the Panda - it's a pain to lose all the electrics when turning the engine off manually in stationary traffic. I do occasionally disable it in creeping traffic, and will sometimes keep the clutch down to prevent it engaging - but only for a few seconds at a time. I'd really like a manual override, with an activation button on the steering wheel, so that I could decide myself when to stop the engine - there's no way the car can know how long it'll be before the engine will be needed again, but I can usually make a pretty good guess. I'd also like to be able to inhibit restarting when freewheeling the car downhill with the engine off - I'm sufficiently experienced to be able to cope with any loss of brake servo vacuum.
 
Do you have a manual transmission? S&S only kicks in when you're in neutral so shouldn't affect hill starts.

How does S&S work in an auto? Do you have to put it in park?

I have 1.2 lounge, dualogic which I've had since the beginning of August. The engine stops when the car comes to a standstill and my foot is on the brake.

Overall, it's a belting little car but I was alarmed to find myself rolling back after stopping on hill and the engine stopped - especially because I had ESR as an extra to make sure I had the hill hold function. I think it's really important in the dualogic because when you move your foot from the brake to the accelerator you can easily roll backwards (n). I then worked out that the ESR only kicks in when the engine is active. So I disable S & S when it gets hilly other wise I need to use the handbrake which is a bit of a pain and the reason I wanted the hill hold in the first place.

And like others on this post, I sometimes disable S & S in heavy traffic because it's quite a lively 'start' and I'm sure it must be less fuel efficient during a heavy commute. I had a Honda civic hybrid that had the same functionality, also automatic, and that just purred into life when I lifted my foot off the brake - the 500 is a bit more animated - but I forgive it because it is just so much more fun to drive - and I can always turn up the awesome Interscope :slayer:
 
1. Some extra wear on the starter & soleniod, though as you say these components should have been 'beefed up' to compensate. Another issue which actually concerns me more is that the fuel management system probably injects a little extra fuel when starting the engine, and this excess fuel could wash oil off the bores & pass unburnt into the catalytic converter - both things you don't want to happen. Also this could actually mean you end up using more fuel, not less, if the engine is continually restarting within a few seconds of it stopping. I'd be really interested to know the 'break-even' time when the fuel saved from stopping the engine idling equals the extra fuel needed to restart it.

I would imagine that with the fact that an engine is so much easier to start when hot that cold that the difference in service life between the non S&S will be evened out by the beefiness of the upgraded components. I will probably fit the bigger battery when my goes as there's space for a bigger battery so why not?
 
My TA starts really easily anyway, the size of the starter is enormous for a 875cc twin.

Also, multi-air 'helps out' when starting by really reducing the dynamic compression ratio of the engine because the valve opening period at idle is very short.
 
PHP:
Also, multi-air 'helps out' when starting by really reducing the dynamic  compression ratio of the engine because the valve opening period at  idle is very short.

Show off!:rolleyes:
 
I'd be really interested to know the 'break-even' time when the fuel saved from stopping the engine idling equals the extra fuel needed to restart it.

Me, too. I can’t find the link, but IIRC a study by the Energy Conservation Center Japan (ECCJ) put the break-even point for manual idle stops at ~5 seconds for a 2000cc, 4 cylinder. Now, with a twin-air with half the cc and half the number of cylinders, I suppose we’d have to double the time, ie 10 seconds. And that’s not even accounting for the battery use by the fuel pump, headlights, computer etc. Considering that, I’m not convinced the start/stop is actually saving me any money at all. YMMV, as always.
 
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