Technical Auto Stop/Start not working

[cinereus]

Since I got the van, the auto Stop/Start never worked. Then, suddenly after 9 months it worked for two days. Then stopped working again and has never worked since.

I'm definitely on flat ground and take the vehicle fully into neutral and the switch is definitely not activated (i.e. not disabled).

Any ideas what could be causing such temperamental behaviour or how to fix it?

 

[bugsymike]

Since I got the van, the auto Stop/Start never worked. Then, suddenly after 9 months it worked for two days. Then stopped working again and has never worked since.

I'm definitely on flat ground and take the vehicle fully into neutral and the switch is definitely not activated (i.e. not disabled).

Any ideas what could be causing such temperamental behaviour or how to fix it?

Just a guess, but check the clutch pedal position sensor up under the pedals, I had something like that on a Vauxhall Combo/Fiat Doblo and the tag had broken off that follows the pedal movement. It did show on a diagnostic check though.

 

[Reg 65]

Can be lots of things - Mine hasn't worked since I connected auxiliary batteries. According to the Fiat Converters Manual (2017) you shouldn't add extra batteries that are more than 20% of the capacity of the main battery, which would give a usable capacity of 10ah - clearly inadequate in a van they advertise as a base for motorhomes!!
Perhaps the most likely cause of your stop start not working this time of year is the computer thinks there is not enough voltage in the battery, or engine not warm enough. I wouldn't worry about it.

 

[cinereus]

Can be lots of things - Mine hasn't worked since I connected auxiliary batteries. According to the Fiat Converters Manual (2017) you shouldn't add extra batteries that are more than 20% of the capacity of the main battery, which would give a usable capacity of 10ah - clearly inadequate in a van they advertise as a base for motorhomes!!
Perhaps the most likely cause of your stop start not working this time of year is the computer thinks there is not enough voltage in the battery, or engine not warm enough. I wouldn't worry about it.

It also wasn't working in Italy in September, so I don't think battery or engine temp is the issue!

 

[bugsymike]

Can be lots of things - Mine hasn't worked since I connected auxiliary batteries. According to the Fiat Converters Manual (2017) you shouldn't add extra batteries that are more than 20% of the capacity of the main battery, which would give a usable capacity of 10ah - clearly inadequate in a van they advertise as a base for motorhomes!!
Perhaps the most likely cause of your stop start not working this time of year is the computer thinks there is not enough voltage in the battery, or engine not warm enough. I wouldn't worry about it.

A good diagnostic check may show up something too.
I am not a fan of Stop/Start either, to me it puts extra strain on the system and after talking to an Auto Electrician, he said even though the parts alternator, starter, battery are upgraded/expensive they still fail.

 

[Neophyte]

If you don't mind that it's not working, just leave it as is. Start-stop systems significantly increase engine wear. The fact that it's no longer working is often simply a sign that your car is "smart" enough to conserve your battery. It's not a defect that needs immediate repair (as long as the car starts normally otherwise).

 

[cinereus]

Yeah I think it's best to just leave it. I was mainly just curious why.

 

[Reg 65]

Start-stop systems significantly increase engine wear.

Exactly.
My understanding is that oil only works properly on sliding parts. Like towing a water skier on shallow water. As long as he is moving fast enough there is water under his skis lifting him off the bottom so very little friction or wear. But as soon as he stops he sinks to the bottom, and you have to brute force drag him scraping along the bottom till the speed lifts him off the bottom again, causing lots of friction and wear. This is what happens every time you stop your engine.

 

[timmycm850]

Just checking, you are taking it out of gear as you describe, are you also fully taking your foot off the clutch pedal

 

[cinereus]

Just checking, you are taking it out of gear as you describe, are you also fully taking your foot off the clutch pedal

Yes, putting into neutral and taking foot off completely. Like I said, it used to work.

 

[timmycm850]

Since I got the van, the auto Stop/Start never worked. Then, suddenly after 9 months it worked for two days. Then stopped working again and has never worked since.

I'm definitely on flat ground and take the vehicle fully into neutral and the switch is definitely not activated (i.e. not disabled).

Any ideas what could be causing such temperamental behaviour or how to fix it?

It begs the question, what sort of joureys did it do in the days before the two days it worked.

 

[cinereus]

It begs the question, what sort of joureys did it do in the days before the two days it worked.

It was two days in a period of driving 4-5 hours or autoroutes a day for a week in 20-25C weather.

 

[timmycm850]

So effectively fully charged and no random wipers/fans/lights use

 

[cinereus]

So effectively fully charged and no random wipers/fans/lights use

Yep

 

[Mike1alike]

Exactly.
My understanding is that oil only works properly on sliding parts. Like towing a water skier on shallow water. As long as he is moving fast enough there is water under his skis lifting him off the bottom so very little friction or wear. But as soon as he stops he sinks to the bottom, and you have to brute force drag him scraping along the bottom till the speed lifts him off the bottom again, causing lots of friction and wear. This is what happens every time you stop your engine.

Wow! That is... poetic.

 

[timmycm850]

Have you checked the full charging voltage, ie when driving along, it should be 14v or upto 14.4v. If its less than approx 13.8v its probably just a bit low for the start stop to charge enough in regular use, it could just be alternator not quite at peak.

 

[jackwhoo]

If it has stop start then it almost certainly has a smart alternator which does not have a constant voltage when engine running

 

[timmycm850]

If it has stop start then it almost certainly has a smart alternator which does not have a constant voltage when engine running

Makes sense

 

[mombassa]

This fixed my start stop issues.
Finally found the issue with this. My 2010 Doblo was coming up with the advisory light saying stop start unavailable. I did all the advised checks lights battery charge earth leads nothing sorted it. Put a scanner on it and it came up with and intermittent error with the brake light switch (error light not activated). Ordered a new switch £8.80 including delivery. Fitted in 2 minutes ( basically go to the brake pedal unclip the 4 wire block, rotate the switch and remove, do the opposite to fit the new one). Turned the engine over (fingers crossed) and no lights no start stop error messages, sorted.

 

[cinereus]

Randomly started working again about two weeks ago. Works about 30% of the time. Also sometimes cuts the engine even on a hill. Sometimes cuts the engine on completely flat road at traffic lights then starts 5 seconds later without touching anything or putting in gear. Actually more annoying like this, did anyone every figure out a way to override permanently?