Excessive revs on start-up

[Candyman]

I have a 6 month old CX-5 2.2 diesel and have suddenly in the last few weeks noticed when starting my car from cold that the revs idle at 1800 rpm and emits a toxic smell/fumes. This eventually clears after a minute or so and the revs drop down to normal.
I have reported this to my dealer who have subsequently checked the car over and have said there is no problem. They have said that this is quite normal as the management system sometimes calls for the extra revs on start-up. With regards to the 'smell' they have suggested that I change from supermarket fuel as this could be the problem.
Has anyone else experienced this please and can confirm or dispute the dealers findings?

FOOTNOTE:
Since posting this message I have pursued Mazda on this situation as I am far from happy with this 'characteristic' and after a further trip and inspection by my dealer I was presented with a copy of an internal report from the Technical department in Japan and it states and I quote....

After a cold start, the regulator valve and the wastegate valve are fully open to enable the exhaust gas to flow through the turbochargers without loosing much exhaust gas heating capacity. Also the VVL mechanism slightly opens on exhaust valve per cylinder during intake stroke in order to recirculate a certain amount of high temperature exhaust gas back to the cylinder.
This is for early activation of catalytic converter and improved gas purification. This does not indicate defect of the parts... UNQUOTE

Make as you will from this but I still see it as a major negative and extremely annoying and frustrating. Will I buy another Mazda? Absolutely not, unless they can overcome this 'feature'.

[Willpower]

As far as the revs are concerned, I would say this is perfectly normal and is the automatic choke bringing the engine up to temperature.  As far as the fumes .  I'm not at all sure that the type of fuel you use is responsible for the fumes. It could just be your DPF doing it's thing. What does it smell like ?
As long as the car drives ok and you have no warning lights, I would tend to ignore your doubts.

[Candyman]

Thanks for your reply. Difficult to describe the actual smell other then toxic exhaust type fumes. It only lasts a few seconds until the revs die down and then everything is fine. It's just annoying as neighbours who walk past when I start up look and stare. Some make comments about it whilst other just start coughing and choking!!!

[MikeTB]

Nothing unusual about a smell. My previous petrol car made an awful smell when the catalyst was cold, but MOT tests confirmed negligible emission levels when hot.

[MikeTB]

I had this recently, but since a good long run it just starts normally.
Smell was quite nasty.

[Ravman]

Hi All, my first post on this forum and looking forward to many more. I have the same issue with excessive revs on start up (goes to 1750 revs) - thing is it only happens when the car is warm (includes hot days first start up of the day). It is akin to how an auto choke would work on a petrol engine - but of course mine is a 2.2 diesel Drive off and everything is back to normal. I've had the car 6 months from new and everything else is fine - just don't know if this is something wrong or if I should be back to the dealers to get it looked at?

[BigAl]

I think this is quite normal. Mine has nearly always done it, as far as I can recall - it just revs high for a few seconds then settles down. I think it can depend on the state of charge of the battery as well - the iStop system sometimes works from start up, sometimes not until you've done a good few miles.

Alan

[johnnyoro]

Hi  my cx5 does this as well I spoke to the dealer and was told it is normal. However as usual I did not believe him and sought the opinion of another dealer and got the same answer . Then still being the sceptical person that I am I did a Google search ( Mazda cx5 fast idle ) and found a Mazda usa smart start guide which explained it ( page three ) . Makes you wonder why Mazda uk have not put some sort of explanation in the handbook. The website was can.dealerprocess.com

[BigAl]

That's interesting, so it's to do with cat warm-up. Direct link below to the document for anyone who wants a read.

http://cdn.dealereprocess.com/cdn/servicemanuals/mazda/2014-cx5.pdf

Alan

[MikeTB]

I have the 175 ps diesel. The strange thing is that this high revs on start is intermittent. It does not happen on most starts.

[twabrigs]

I have the 175 ps diesel. The strange thing is that this high revs on start is intermittent. It does not happen on most starts.

Likewise. I'd say it only does this once every 30 or 40 starts for me. I've never come across it on any other car but it seems 'normal' for this engine.

[BigAl]

Same here, having thought about it. I'd hazard a guess then that it does this every so-many start-ups to ensure that the cat is warmed up properly, especially if being used for a lot of short runs? At least we now know all the cars are doing the same thing.

Alan

[ROCKETRON]

I think it depends on the ambient air temperature/conditions when you start. Mine tends to do it on a cold start on a warm day,not usually in cold weather.

[xtrailman]

These are the conditions required for the high revs according to Mazda.


High revs at start up.


 

Case Reference: 1-517969912

 

Thank you for your recent email.

 

Having discussed your concern with our Technical Department, I can advise the following:

 

High idle speed is a normal function of the SkyActiv Diesel engine on start up, and is not related to any PCM updates; this has always been a feature of this engine.

 

After a cold start, the regulating valve and the wastegate valve are fully open to enable the exhaust gas to flow through the turbochargers without losing much exhaust gas heating capacity. Also the VVL mechanism slightly opens one exhaust valve per cylinder during intake stroke in order to recirculate a certain amount of high temperature exhaust gas back to the cylinder.

This is for early activation of the catalytic converter and improved exhaust gas purification. This does not indicate defect of the parts.

 

<Operating Requirement>

1. Water temperature (ECT) at engine starting: from 15 to 32 degrees Celsius.

 

Intake air temperature (IAT) at engine start: from 15 to 35 degrees Celsius.

Barometric pressure at (BARO) at engine start: from: 91 to 200 kPa.

2. Gear position: P, N, D with the engine idling (Accelerator pedal not depressed)

 

This is mentioned in the owner’s manual

 

<Owner’s Manual>

This concern is mentioned in the O/M “When Driving Start/Stop Engine” as follows:.

 

After starting a cold engine, the engine speed increases and a whining sound from the engine compartment can be heard.

This is for improved exhaust gas purification and does not indicate defect of the parts.

 

In closing, I trust the above information clarifies your Mazda CX-5 is operating as intended.

 

Yours sincerely

 

 

Jon Haywood-Smith

Regional Customer Relations Manager

_____________________________

Mazda Motors UK Ltd

[kiakid2]

Having been to the south of France with my caravan for 5 week, the car has decided to go through the Accelerated Warm up System (AWS) cycle almost every cold start and is driving me mad.
I am not happy to drive away until the revs have dropped back to idle on the basis that it can’t be doing the clutch any good.

Would it be the French diesel that I have been using causing this I wonder, as previously over the last 10 months in UK, it has only occurred on an occasional basis.