Rev changing on auto what is normal

[Isa0324]

Hi just thought I'd ask here for some information before I call the dealer and possibly look a bit silly.

I have a e class e350 2018 with only 2300 miles on the clock.

Usually the car with normal driving on comfort mode changes gear at 1500 rpm
But in the last 2 months on 3 occasions it has changed gears ar a highier rev off 1800-2000 rpm with normal smooth ..driving this happens with the engine warm. Not when it has just started

Then if I drive the car again after 2 hours it goes back to normal.

Is this normal or am I panicking and over thinking lol

Thank you

 

[Smart320]

Assuming it is a diesel then DPF regeneration would probably account for this , regeneration only happens when engine is hot and it causes rpm to rise when idling.

 

[cdcls]

Yep defo regen on the dpf. Mine does this exactly the same. You'll probably also notice the idle is slightly higher as well if you stop while this is happening.

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[Isa0324]

Assuming it is a diesel then DPF regeneration would probably account for this , regeneration only happens when engine is hot and it causes rpm to rise when idling.

What is DPF regeneration?
Yes it is a diesel. Excuse me for sounding stupid but in conclusion it is perfectly normal and nothing to worry about ?

 

[cdcls]

What is DPF regeneration?
Yes it is a diesel. Excuse me for sounding stupid but in conclusion it is perfectly normal and nothing to worry about ?

Yep, totally standard.

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[Smart320]

The engine has a filter in the exhaust , a Diesel Particulte Filter which catches all the small carbon particles in the exhaust gases in order to clean them. However after a time ( depending on how slowly or quickly the car has been driven it becomes partially blocked ( full ) and so the engine is electronically set up to then increase the temperature of the gasses passing through the DPF ( by injecting unborn T fuel into it ) in order to burn off the excess carbon . This happens more frequently if the car is used in town rather than at faster crying speeds, hence diesels not recommended for low mileage town use.
Well at least this is my non technical understanding of how it works, you can always Google the subject.

 

[zipdip]

I suggest you take the car out for some decent runs,say a 50 mile round trip ,then the car will regenerate and you will not even notice it happening.

 

[PobodY]

If it never gets a good run, it will never really complete the regeneration cycle... and then the filter gets knackered and has to be replaced.

 

[Isa0324]

I do use the car mainly in town. And out of 2300 miles on the clock. About 800 are motorway.

I am relieved. I thought my gearbox had started playing up.

Thank you all for information

 

[Bobby Dazzler]

I do use the car mainly in town. And out of 2300 miles on the clock. About 800 are motorway.

I am relieved. I thought my gearbox had started playing up.

Thank you all for information

When you feel it happening again, try to take a detour on a fast route, ideally 20 minutes or so.

It is disconcerting when you’re not used to regen. I was very worried when I got out of my car only to hear an almighty racket and awful smell, because I stopped part way through. That was an Audi - no longer with us - but I assume it’s much the same for all makes and models.

 

[400ixl]

Regen's typically happen around every 300 miles or so regardless of whether its been used in town or on a motorway. If it recently did a regen, going for a 50 mile run as suggested will just waste money as it will not regen as it doesn't need to. If it is due one, then it will.

Seeing as you are seeing evidence of it doing a regen on its own cycle then you don't need to do anything other than enjoy the car. Most regens happen without people even noticing it.

As long as you are not doing short journeys all the time then the car will look after itself. a 20 minute journey even around town will still give it time to do a regen if required.

 

[Isa0324]

When you feel it happening again, try to take a detour on a fast route, ideally 20 minutes or so.

It is disconcerting when you’re not used to regen. I was very worried when I got out of my car only to hear an almighty racket and awful smell, because I stopped part way through. That was an Audi - no longer with us - but I assume it’s much the same for all makes and models.

Wait could a bit of a burning smell I get now and again me associated with dpf regen

 

[400ixl]

Yes, the exhaust gets heated up and can have a smell if you get out of the car close to one completing or whilst one was running. Perfectly normal.

More modern cars don't really smell very much anymore and you shouldn't really notice it very often. Earlier cars when the technology was new could be horrible.

 

[nickpb]

It never ceases to amaze me the number of new MB diesel owners (other manufacturers are available) who don't know about DPFs and regeneration.

Don't get me wrong, this is NOT a criticism of the owners but rather a criticism of the dealers who sell the cars and obviously don't bother to explain the foibles of the diesel engines. They obviously expect that every new owner has the time, and can stay awake long enough, to read the incredibly thick (and repetitive) Owner's Manual before using their new car.

They need shooting!

 

[BMF]

My first foray into diesel regen was in a Vauxhall Vectra elite navi, bought secondhand. The dealer didn't say anything about it on purchase/collection. I used to get a strong diesel smell and increased rpm and rough idling, a little worrying I thought, so I used to switch off and restart. I part exchanged it for an Insignia from a local Vauxhall dealer, again no mention of the regen phenomena but by then I'd done some research, and it's thanks to the helpful nature of fellow forum members that this info is available.

 

[nickpb]

It never ceases to amaze me the number of new MB diesel owners (other manufacturers are available) who don't know about DPFs and regeneration.

Just found this in a Nissan brochure. Why can't MB tell owners this?

====================================================================

A Gasoline Particulate Filter (GPF)
or
Diesel Particulate Filter (DPF)
forms part of the vehicle’s exhaust in order to limit the amount
of soot particles contained within the exhaust gas passing into the atmosphere.
When the amount of soot in the filter reaches a specific level, this needs to be reduced in order to maintain the filter’s
function.

This reduction is called
‘REGENERATION’
and is carried out by the vehicle’s electronic control system which raises the exhaust gas
temperatures during normal driving. If a vehicle requires frequent regeneration due to driving style, these high temperatures
cause the engine oil to degrade more quickly.
However, from 2011 onwards Nissan vehicles were fitted with an
OIL CHANGE SUPERVISOR
(OCS)
as well as a GPF or DPF to help
monitor the condition of the oil and ensure the quality never falls below a minimum level.

WHAT IF I ONLY DRIVE SHORT JOURNEYS?
If the vehicle is only driven for short journeys, or at low speed, then it may not be possible for regeneration to occur. In th
is situation,
the below warning lights will be illuminated on your dashboard.
Please refer to your Owner’s Manual for further information.
After seeing these warning lights you need to drive, as soon as possible, above 40mph until the light goes out. This can take u
p to
30 minutes depending on the amount of soot collected in the filter.

WHAT IF I IGNORE THEM?
If you continue to drive at low speeds the exhaust gas temperatures cannot rise, so regeneration cannot occur. In this instance
a combination of the below warning lights will be illuminated on you dashboard.
In this case, and in order to protect the engine and DPF Filter, the vehicle will require
‘SERVICE REGENERATION’
which can only be carried
out by a workshop equipped with Nissan diagnostic equipment. You will need to go to your nearest Nissan dealer in case the oil and filter
needs to be replaced.
With a Nissan Service Plan you will benefit from genuine Nissan parts and Nissan Genuine Motor Oil, which have been engineered
specifically for Nissan vehicles.

As ‘SERVICE REGENERATION’
is not a manufacturing fault, so the cost will
NOT
be covered under warranty.