Stop start question

[otherclive]

I tend to use mine in S-S as that way no clutches are running even in light contact. But I don’t really monitor mpg other than the total per trip, and accumulated total, as there are so many variables. I’ve generally taken the view that mog is what it is and it’s not that high up on my list of needs. To my mind biggest advantage of S-S is cutting polluting


This link might be interesting.

Automatic Start-Stop Tech Saves More Fuel Than You Think

You might think it's annoying and pointless. It's not

www.roadandtrack.com

 

[Buckman]

I tend to use mine in S-S as that way no clutches are running even in light contact. But I don’t really monitor mpg other than the total per trip, and accumulated total, as there are so many variables. I’ve generally taken the view that mog is what it is and it’s not that high up on my list of needs. To my mind biggest advantage of S-S is cutting polluting


This link might be interesting.

Automatic Start-Stop Tech Saves More Fuel Than You Think

You might think it's annoying and pointless. It's not

www.roadandtrack.com

The video or speech may be more applicable to someone that works and is in heavy traffic constantly. From our home to the nearest town is about 10 miles and even driving around the town we would only encounter one set of traffic lights.

Even if we go into the city which is very seldom, not many traffic lights and as we are traveling during the day, traffic is generally light. I think Stop Start should be an option of vehicles as I find it quite annoying.

 

[Jcloughie]

The video or speech may be more applicable to someone that works and is in heavy traffic constantly. From our home to the nearest town is about 10 miles and even driving around the town we would only encounter one set of traffic lights.

Even if we go into the city which is very seldom, not many traffic lights and as we are traveling during the day, traffic is generally light. I think Stop Start should be an option of vehicles as I find it quite annoying.

A major reason cars have SS tech is to reduce measured emissions. So the model comes into a lower tax band. Therefore they cannot easily make it an option. Another reason is there is a lot of wiring, technology, and programming incorporated into the vehicle. For example, mine uses a two battery system. So, on the production line, it would be a major thing to leave it out.

If it does not suit you. You could ask your dealer to change the default to ‘off’.

John

 

[Buckman]

A major reason cars have SS tech is to reduce measured emissions. So the model comes into a lower tax band. Therefore they cannot easily make it an option. Another reason is there is a lot of wiring, technology, and programming incorporated into the vehicle. For example, mine uses a two battery system. So, on the production line, it would be a major thing to leave it out.

If it does not suit you. You could ask your dealer to change the default to ‘off’.

John

I have already asked and it cannot be done unless you are prepared to pay really big bucks. Just as easy to remember to simply switch it off. LOL!

 

[RogerL]

I tend to use mine in S-S as that way no clutches are running even in light contact. But I don’t really monitor mpg other than the total per trip, and accumulated total, as there are so many variables. I’ve generally taken the view that mog is what it is and it’s not that high up on my list of needs. To my mind biggest advantage of S-S is cutting polluting

I hadn't thought of stop-start being a benefit on DCT transmissions, but it would definitely seem to be.

 

[Lutz]

The start-stop function is necessary in order for the manufacturer to be able to achieve prescribed exhaust emission limis.

 

[Buckman]

Thread is old, but I came across a post stating "On a turbocharged engine stop-start will eventually cause premature turbo failure if the vehicle does not have sufficient oil flow to the turbo spindle for at least 1 minute after engine stop. A water cooled turbo can reduce the likelihood of spindle damage if coolant flow continues after engine stop. If a stop-start engine does not have an electric oil pump or an electric water pump for the turbo (or the engine) a replacement turbo should be budgeted for when the vehicle is out of warranty. Switching off stop-start will prolong the life of your turbo charged engine."

I wonder if there is any truth in this?

 

[otherclive]

I’ve had a 2 litre Skoda turbo diesel and a 1.5 petrol turbot and both had stop start. You need to look at when it functions. Rarely do you have a rapid stop when the engine is at very high temperature as when towing. Going into motorway services you have a cool down period as you leave the motorway, then time spent parking up. In towns the turbo isn’t running hot anyway.
I tend to turn stop start off in heavy slow moving traffic anyway; more for consideration for the battery an mechanicals. But do we hear of many turbos failing after warranty which could be high mileage or low mileage. Anyway with a warranty till 2029 I’m quite relaxed.

 

[JTQ]

I wonder if there is any truth in this?

There is absolutely no doubt that stopping a very hot turbo turbine there will be some heat increasing the temperature of the tubro's journal shaft, and hence raising the oil film temperature. In some capital projects we had a maintained oil feed to turbos, to purge this heat and to keep a feed during spin down.
In the turbo design industry, where I was peripherally involved over twenty years back, there was very real concern this temperature in unmaintained oil feed turbos, could easily reach levels that would break down the oil. The biggest concern in that is that gums and carbon would be formed and some bond to the rotating parts, particularly the shaft, and here the crunch point in time cause a loss of balance. That being a progressive killer of the turbo. The wider adoption of fully synthetic oils, those of true high quality, as opposed to just labelling, to some extent mitigated this in part.

I subscribe to the thinking stopping an overly hot turbo promptly as can happen in stop start is from turbo longevity no good thing, though environmentally, not burning fuel has to be.
When towing I will not just switch off my vehicles the moment I stop, I easy off the turbos duty and will idle for some tens of seconds before doing so. Afterall I would be the one to pick up the bill, which could be into thousands.

 

[RogerL]

I’ve had a 2 litre Skoda turbo diesel and a 1.5 petrol turbot and both had stop start. You need to look at when it functions. Rarely do you have a rapid stop when the engine is at very high temperature as when towing. Going into motorway services you have a cool down period as you leave the motorway, then time spent parking up. In towns the turbo isn’t running hot anyway.
I tend to turn stop start off in heavy slow moving traffic anyway; more for consideration for the battery an mechanicals. But do we hear of many turbos failing after warranty which could be high mileage or low mileage. Anyway with a warranty till 2029 I’m quite relaxed.

Many cars disable the stop-start when towing so that aspect is rarely an issue.

With interrupted active DPF regenerations needing much heat dispersal, I'd expect any Euro 5/6 diesel to be able to cope with sudden switch off - but I wouldn't be surprised if many can't.

There's a general consensus that batteries only last 3-4 years, particularly in stop-start duty - however in good conditions they will last much longer than that albeit at lower capability - this lower capability usually cause the stop-start not to operate.

My original car battery is over 8 years old and not showing any obvious signs of ageing - however I'm not going to tempt fate this winter so will replace it this month, and relegate it to caravan leisure duty - which will no doubt cause prophesies of disaster from my AWS technician when he services it.

 

[Dustydog]

Back in the 90s hot hatch turbos like the Renault 19 had a label on the dash staying the engine must be idled for 60 seconds before switching off.
The problem was the oil back then was carbonising on the turbo shaft bearings resulting in semi oil starvation and ultimate failure.

I suspect todays oils and construction of turbos result in very few failures.
My VWs start stop does not function when towing. This is because the caravan fridge and charger are drawing power . The SS can be permanently turned off by removing the voltage sensor on the battery terminal.
Our Kia actually has a dedicated switch on the dashboard for the auto stop.
If you are concerned about the turbo then just leave the engine idling for a minute before switching off.

 

[RogerL]

The SS can be permanently turned off by removing the voltage sensor on the battery terminal.

That's not a good idea as the car battery won't get charged and other functions may be affected.

On most VW Group cars, the stop-start can be changed to default to off, rather than defaulting to on - but this needs diagnostic software such as VCDS - the dealers' ODIS system could do it but dealers generally refuse to.

 

[otherclive]

If you are concerned about the turbo then just leave the engine idling for a minute before switching off.

That's exactly what I would do with my first four turbo cars, all of which were tow cars, and I never had any issues with the turbos. Since then oils have improved and no doubt the makers have introduced some improvements too, such as switch off when towing, or auto run on.

 

[Dustydog]

That's not a good idea as the car battery won't get charged and other functions may be affected.

On most VW Group cars, the stop-start can be changed to default to off, rather than defaulting to on - but this needs diagnostic software such as VCDS - the dealers' ODIS system could do it but dealers generally refuse to.

Odd that Kia actually fit a switch and VW don’t. I’m happy with mine as it is and won’t be changing anything👍

 

[JTQ]

Many cars disable the stop-start when towing so that aspect is rarely an issue.

To my surprise, Land Rover with their Discovery 4, which was marketed and extensively used for quite heavy duty towing, did not disable stop start even in ours that was factory fitted for towing.
This driver does, and extends that to solo as well, only activating it when stuck in delays and where travel itself is stop start.

 

[Buckman]

As a matter of routine, when getting into the vehicle I normally switch off the Stop start system. I don't think mine is automatically disabled when towing as I do not have the fridge connection fitted,

 

[RogerL]

Odd that Kia actually fit a switch and VW don’t. I’m happy with mine as it is and won’t be changing anything👍

Disabling the Stop-start by a manufacturers switch is fine - it was the crude removal of the voltage sensing I was warning about.

My 2016 Touareg has a stop-start switch - as delivered the stop-start defaults to on but can be switched off using the switch - I've changed the settings with VCDS diagnostics to default to off but can be switched on with the switch.