Mazda CX-5 2018 diesel - White smoke problems

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Wed 10 Jan 2024 17:44
Mazda CX-5 2018 diesel - White smoke problems - RoundTheBend

Hello everyone

We've had this car from new and I think it was last year that we started getting white smoke every now and again. I just always wrongly assumed this was a regen, but I now believe it's something else.

This morning it was pretty cold 0C. Car started up OK, but maybe about 2-3 minutes/half a mile down the road white smoke for several minutes when driving on 30mph roads. When I stopped and was stationery it stopped billowing out (but was still smoking a bit), but then once I drove off again, it resumed. It always stops when the engine starts to get warm and then it's totally fine. The smell is like a bad diesel smell, so I believe it is unburnt diesel fuel. This is the same pattern every time it happens. Only ever happens when the engine is cold and seems to be exacerbated when it's very cold outside. It does still happen in the summer months though. Seems like it's happening more though as time goes by and when it's cold outside.

I've also noticed recently that when the car is cold the automatic gear changing can sometimes feel a bit sluggish and not so smooth.

There are no errors messages and the glow plug light does light up momentarily when the engine starts, but doesn't stay on.

Driving profile is very short school runs in the morning and afternoons with longer A road/motorway journeys at the weekends.

Did a lot of searching this morning and glow plugs seem like a suspect. Is this most likely to be a glow plug problem based on the pattern?

Many thanks

Edited by RoundTheBend on 10/01/2024 at 17:48

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Wed 10 Jan 2024 18:48
Mazda CX-5 2018 diesel - White smoke problems - Adampr

It won't be glow plugs as they switch off after a few seconds.

Have you checked your oil level? Mazda diesels have a bit of a reputation for burning oil.

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Thu 11 Jan 2024 10:08
Mazda CX-5 2018 diesel - White smoke problems - RoundTheBend

Thanks for you reply.

More smoke again this morning. 1C on the car thermometer. Pretty much the same as yesterday. Smoke started when engine was just above 50 and stopped just before 75. Probably lasted about 2-3 minutes. I let it sit stationery to warm up for longer after dropping off my son, as it smokes less when it isn't moving.

The car has literally been in for a service at our local independent garage the previous day and had an oil change, so this is the second consecutive morning after the service. This is the second service there, with the previous three at the Mazda garage.

I checked the oil this morning.when cold and, as the manual suggests, after driving it for 15 minutes (and waiting more than 5) and the level is above the two holes. I'd say about half way between the last hole and the X. Our driveway has a very minimal incline, but it does seem on the high side. Manual says that oil level is OK is between the two holes. The oil is black.

Thanks

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Thu 11 Jan 2024 10:44
Mazda CX-5 2018 diesel - White smoke problems - skidpan

White smoke is a by product of a regen, we had 3 cars with DPF's and they all did it on occasions.

But unlike Mazda's our Ford, Kia and BMW completed the regens and we never had an oil dilution problem.

Driving profile is very short school runs in the morning and afternoons with longer A road/motorway journeys at the weekends.

But unlike yours our use was appropriate for diesels with a DPF. My commute was a 30 mile round trip and the wife's was a 40 mile round trip (4 days a week) plus visits to the MIL at the weekend, a 75 mile round trip.

Once we stopped doing that kind of mileage and replacement was due we bought petrols.

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Thu 11 Jan 2024 13:00
Mazda CX-5 2018 diesel - White smoke problems - Andrew-T

The oil is black.

Nothing to worry about there - fresh oil very soon gets black in a diesel engine, even if the drain has been almost complete.

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Thu 11 Jan 2024 15:21
Mazda CX-5 2018 diesel - White smoke problems - RoundTheBend

The question is, does this sound like a regen or something else? Would the car regen so soon into the journey from a cold start?

It definitely seems worse when it's very cold outside from a cold start in the morning. It did the same thing last year when we had the snow. Temperature definitely seems to be a factor.

Forscan says it's been 188 miles / 304km since the last regen.

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Thu 11 Jan 2024 16:00
Mazda CX-5 2018 diesel - White smoke problems - elekie&a/c doctor
Do you actually have a problem or is this just a characteristic of this diesel model ?
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Sun 14 Jan 2024 01:02
Mazda CX-5 2018 diesel - White smoke problems - focussed

Glow plugs are not just there to aid cold starting a diesel engine nowadays.

“Few drivers realise that glow plugs make a massive difference to their car’s ability to meet current emissions standards. With modern engines, plugs must be able to glow for several minutes after the engine is running (‘post-glow’), to reduce exhaust emissions. Many car manufacturers also demand glow plugs that can glow intermittently: in certain driving situations, these types become energised even when the engine has warmed up, preventing the engine from over-cooling when the car travels downhill. They also help during regeneration of the diesel particulate filter (DPF) by raising the combustion chamber temperature, which in turn increases exhaust gas temperature.”

www.ngkntk.com/newsroom/blog/emea/winter-glow-plug.../

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Tue 16 Jan 2024 09:30
Mazda CX-5 2018 diesel - White smoke problems - RoundTheBend

Thanks to everyone that replied.

It was stuck in a short journey "regen loop".

Got my other half to drive and Forscan showed that the car was trying to do an active regen. It just needed a few more minutes to complete - it pauses the regeneration when the car is stationery.

Our journey was just not long enough for the regen to complete (maybe the freezing conditions were a factor too). I'm guessing that there may also be some residual raw diesel in the DPF system from the previous failed regen attempt(s) and that was compounding the problem further and creating the smoke along with the unburnt diesel smell.

Forscan has allowed much better insight into the number of regens and distance between, so that gives better awareness of the average interval going forward as there is no visual indication given to the driver!

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Wed 17 Jan 2024 14:40
Mazda CX-5 2018 diesel - White smoke problems - Danny Payne

Is the white smoke not just a case of a cold engine - and stops when the engine warms up?

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