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[glasgowgenie]

Hi all, I have a 2015 forfour with only 20k on the clock.  Recently from a cold start, the idling has been rough and sometimes the engine cuts out.  Sitting at light is lights feels like being on a roller coaster!  This seems to resolve itself when the engine heats up and idles fine just below 2.  However stop/start never gets the green light.

I've had a read through the forum ( which is brilliant )   and wonder if this is possibly a TVA issue.  Any advice, suggestions, help would be greatly appreciated.

[CrazyG]

So...yours is a Gen2 ForFour...a W453...

The StartStop system when it was introduced to the 451 (ForTwo) was one of
the biggest problems, and Rob at S2Smarts always advises owners to switch
it off once the vehicle has started...and to do it every time, as in truth unless
you are driving constantly in the city in stop start conditions it really does not
gain you much in the way of improved mpg....that and the belt that takes all
the strain of starting needs to be changed at every yearly service. Failure to do
that can result in catastrophic engine damage.

I doubt whether your issue is actually linked to the TVA as that is a 'known' 454
ForFour issue. As I am not 'au fait' with issues with the 453 ForFour may I suggest
that you call Rob at S2smarts on Monday (01923 771222) and talk to him about
the problem you are having for his advice/guidance.

[glasgowgenie]

Many thanks for the response.  My V5 says it's a 451 model.

I've tried to resolve it with the stop/start on and off and it make little difference to the problem.  Looking through the manual, it says the stop/start only works when a number of things are met and wondered if it was one of those things.  It's weird that it's fine after driving for a while and the engine has heated up.

[Brabs]

Hmm, if your V5 says that your smart is a 451 then I’m afraid that although welcome here you are on the wrong site as you have a Smart fortwo! 🤔

[mr singh]

correction on what model glasgowgenie has. he DOES have a 453, BUT on the V5 it will say its a 451.

there have been issues with rough idle with the 453 and the solution to fix it is on our 'sister' website
evilution.co.uk but you will need to subscribe to view the fix

https://www.evilution.co.uk/index.php?menu=info&mod=1427

That link when opened does start off by saying :-
"It's now becoming a common issue with the 900cc turbo 453 engine."...
That could also be construed to mean that it could also be a fault with
the non-turbo engine, ok. (Is yours a turbo or non-turbo 453 ForFour ?)
If it is NOT, let us know and one of us who does have subscription to
that website will ask 'Evil' if it is also the case with the non-turbo.

[glasgowgenie]

Many thanks.  It's definitely a Forfour.

[CrazyG]

As per mr singh's suggestion to 'sign up' on the Evilution website
I note that there are issues with the 453 in respect of the Stop/Start
system and the battery that has many unusual and unexpected side effects,
and also how to do a Throttle Body Reset.

So...if you do subscribe and join that great website, then at the Homepage
go to the top left and 'deselect' (by clicking on the images) all the models
that are not yours...then...
you will get relevant info to the 453 in the left column headed 'Info guides and mods',
and in that you will see 2 references to Start/Stop and lower down still the one for the
Throttle Body Reset.

As you mention in your  initial post that you never get the 'green light' on the Stop/Start
then I would tend to think that this points to a battery issue....but do not take my word
for it. Ask the man for that website...I would if it were me.

[glasgowgenie]

Many thanks. I’ve paid & signed up and will follow the guidance.

Thanks again. Much appreciated