Hi,

 

For the past few months my 60 plate 2010 2.0TDI PD has been advising a change down in gear when the speed and revs are appropriate for the current gearing.  The ride also becomes 'jittery' as if there are not enough revs even though there are.

 

I'd heard that the DPF can be a problem especially on the PD engine but the engine warning light for the DPF is not lit.

 

I asked my Skoda dealer if this was serious and they said it was probably due to short journeys and needing to burn off carbon in the DPF by increasing the revs and heat.

 

I use it daily and the commute is about 8 miles on faster roads but it also happens on longer journeys.

 

Any ideas?

Sounds more like DMF than DPF - the DMF or dual mass flywheel absorbs torsional vibration in the drivetrain, keeping the car smooth at low revs but can lead to unwanted juddering when it breaks. This happens at lower revs usually and when pulling away. Your commute is short enough that the DMF might be a problem, especially on the PD engine, so ask about both.

I think it Sounds like regen of the dpf

Does it go away after 10 minutes or aprox 10 km ?

I think you're mixing 2 things up.

 

1. The recommended gearing indicator is an indication what the best gear would be for your current speed. This is indicated on your Maxidot screen. It's a number (1-5/6) with an arrow of the car thinks the gearing is too high or low. In practice, when you slow down without changing down, it will show the downward pointing arrow telling you you're in too high a gear. When you're accellerating, it will show the upward pointing arrow telling you to change up (in my opinion the car does this too fast)

 

2. The DPF warning light will be a yellow light on the dash and a warning in the maxidot, something along the lines of "DPF regeneration needed" or something. Just follow the instructions in your user manual to clear it. (If you don't have a user manual, click HERE for the online version from Skoda)

 

 

If you have excessive vibrations when driving along it could be due to being in too low a gear (especially if you follow the on-screen shift recommendation all the time, it's way to low). Try driving in the gear that feels good to YOU, not what the car maker thinks you need to do in order to lower the emissions...

 

If you get the DPF warning light, I cannot stress enough you HAVE to clear it! Just stay out, try to find a motorway and follow the instructions in the manual. It should clear.

if the DPF warning light comes on the "damaged" is done.. Maybe you can make it go away if you follow the above instructions. 

 

to my understanding the car automatically regen the DPF when it has to.

It doesn't show any warnings ect. 

 

But the gear shift indicator is a tell sign that the car is doing something. 

The reason why is want's to shift down is that i needs a certain revs to clear the soot.

 

When it regens the DPF it injects extra fuel into the filter and i think thats what you are feeling.

It gets a bit jerky when you accelerate and the car makes a little more noise.

 

After aprox 10 minutes or 10 km it goes away and everything is normal. 

Hi Thanks for the replies!

 

Pshcholist - that sounds interesting! Will look into that as it sounds plausible.

 

Steffan - sometimes it does but sometimes it doesn't! You can be on a long journey and then the engine does a 'hiccough' and then the gear change tells you to change down and the ride becomes juddery!

 

Too Tall - Normally you can say do 30mph in 4th gear at about 1500rpm no problem (the indicator normally tells you to be in this gear for that speed/RPM) then all of a sudden it will tell you to change down, the engine feels like it is struggling etc. You change down but it tells you to change again 2nd gear at 3000RPM to do 30mph?  The same on a motorway at 50-60 6th gear is fine and the car pulls well but when this happens it wants you to be in 4th with the engine revving!  I try to ignore it and drive to the rode and conditions but there is a worry it is something catastrophic waiting to happen!

 

Again thanks for the info!

If the DPF warning light comes on the "damaged" is done.. Maybe you can make it go away if you follow the above instructions.

 

I'm not sure what you mean by 'damage' but having the DPF light come on is not the end of the world. The car is simply alerting the driver to the fact that it needs help to perform a regeneration or 'clean' of the DPF. This is normally due to a lack of long enough jorney's that would ordinarily allow the car to do it itself.

 

Now if you get the DPF light and EML together, combined with 'limp-home' mode then you are indeed in a worse situation. Here you need a garage or someone with VCDS to perform a forced regen for you as the car will no longer try to clear the DPF itself. This will only happen if you ignore the DPF light by itself, or if one of the DPF sensors fails.

 

When I first read the opening post I wondered if the car was deliberately asking for a lower gear in an effort to generate more heat and allow the car to regen. I've never heard of this before though. However asking for a change from 3rd to 2nd at 2,000RPM is clearly not something Skoda are going to program the car to do.

 

Afterall, this is what the DPF light is for.

 

My recommendation here would be to get the car scanned so that you can read any fault codes logged. This will direct you to the area causing the issue. Normally DPF faults are only logged once you get a light on the dash (DPF, EML or glowplugs), however the misfire and issues with the gear change recommendation would have me thinking there will be something to be read.

When i do 80 km/t In fifht gear (Greenline) every thing is ok. But when it regen it wants me to change to fourth gear to get higher revs. I just need around 1600 - 1700 in fifth before the change Down symbol diseappears.

It Sounds wierd that you need 3000 rpm !

And i can only feel it a little in the car. Not much.

I read somewere on this page about different stages that the dpf regen before it flash the warning.

If i were you i would take it for a long run and drive for 15 min around 3000 - 3500 to clear it. Remember that the car/Oil need to be warm :-)

Silver - if the dpf flash then there has been alot of failed attempts of regen. So if you fail to clear the Warning you Are looking for a garage.

Silver - if the dpf flash then there has been alot of failed attempts of regen. So if you fail to clear the Warning you Are looking for a garage.

 

Some useful information on the DPF...

 

Firstly if needed there is a warm up phase:

Warm-Up Phase

To heat up a cold oxidation catalyst and particulate filter as quickly as possible and thus bring them to

operating temperature, the engine management system introduces a post-injection after the main

injection.

Basically then there are 5 Levels of Regeneration

Passive Regeneration

Active Regeneration

Customer-Initiated Regeneration Drive

Service Generation

and Distance Regeneration

The first 4 are based on the measured load on the actual DPF and the final one is NOT

Distance Regeneration

“Distance regeneration” is a distance-dependent regeneration of the particulate filter. The Engine

Control Module (ECM) J623 initiates an active regeneration automatically if during the last 466 to

621 miles (750 to 1000 km) of travel no successful regeneration has taken place, regardless of the load condition in the diesel particulate filter.

Distance regeneration serves as additional safeguard to minimize the load condition of the diesel

particulate filter.

Update with info on each type:

Passive Regeneration

During passive regeneration the soot particles are continuously burned without the intervention of

Engine Control Module (ECM) J623. This occurs primarily at higher engine load, such as

in highway driving, when exhaust gas temperatures range from 662°F to 932°F (350°C to 500°C).

At these temperatures the soot particles are converted into carbon dioxide through a combustion

reaction with nitrogen dioxide.

Active Regeneration:

In a large portion of the operating range the exhaust gas temperatures are too low for a passive

regeneration. Because soot particles can no longer be eliminated passively, soot accumulates in the

filter. As soon as a specific soot load has been reached in the filter, the Engine Control Module

(ECM) J623 initiates an active regeneration. The soot particles are burned off at an exhaust gas

temperature of 1022°F to 1202°F (550°C to 650°C).

Active Regeneration Function

The soot load of the particulate fi lter is calculated by two pre-programmed load models in the Engine

Control Module (ECM) J623. One of the load models is determined from the driving profile of the user and the signals from the exhaust gas temperature sensors and Heated Oxygen Sensor (HO2S) G39.

Another soot load model is the flow resistance of the particulate filter. It is calculated from the signals

of Exhaust Pressure Sensor 1 G450, Exhaust Gas Temperature (EGT) Sensor 3 G495, and Mass Air

Flow (MAF) Sensor G70.

Customer-Initiated Regeneration Drive:

An exhaust gas temperature high enough for particulate filter regeneration is not reached when

the vehicle is only driven for short-distances. If the load condition of the diesel particulate filter reaches a

threshold value, Diesel Particle Filter Indicator Lamp K231 in the instrument panel will light up.

This signal prompts the driver to perform a regeneration drive. The vehicle must be driven for a

short period of time at increased speed to ensure that an adequately high exhaust gas temperature

is reached. The operating conditions must remain constant over the period for a successful

regeneration.

Details of the driving behavior required when the Diesel Particle Filter Indicator

Lamp K231 comes on can be found in the Owner’s Manual

Service Regeneration:

If the regeneration drive is not successfully completed and the load condition of the diesel

particulate fi lter has reached 1.41 ounces (40 grams), Diesel Particle Filter Indicator Lamp K231 and Glow

Plug Indicator Lamp K29 will light up simultaneously. The text “Check Engine – Workshop” will appear

in the instrument panel display.

This prompts the driver to visit the nearest service shop. In this case, the Engine Control Module

(ECM) J623 blocks active regeneration of the diesel particulate filter to prevent damage to the filter and

the particulate filter can only be regenerated by a service regeneration with the VAS 5051.

When the load condition reaches 1.59 ounces (45 grams), service regeneration

is no longer possible. Because the danger of destroying the filter is too

great with this load, the filter must be replaced.

These drive aids are a right pain, just drive it how you would if they weren't there, why give yourself such a headache over nothing,

 

Regarding the DPF if it's doing a passive you will still notice it, the engine note becomes more gruff and the smoothness is effected as it's basically overfueling itself, i.e running on choke.

I'm not so sure. Passive regen is when the soot is burned off through normal operation.

 

There is no intervention from the car at all during a passive regen.

To confirm the previous post - Passive regen happens once the engine is running at enough load to keep the exhaust hot. Once the exhaust is hot enough to break the soot down chemically (Waste heat while the engine is under cruising load is more than enough for this) the DPF will lose any soot it collected while the engine was cold or when it was accelerating hard during the drive. It's part of the reason you shouldn't drive the car hard for a couple of minutes before shutting the engine off too - the other more important reason is so the oil flow to the turbo doesn't stop while the turbo is hot enough to burn the oil in its bearings.

To confirm the previous post - Passive regen happens once the engine is running at enough load to keep the exhaust hot. Once the exhaust is hot enough to break the soot down chemically (Waste heat while the engine is under cruising load is more than enough for this) the DPF will lose any soot it collected while the engine was cold or when it was accelerating hard during the drive. It's part of the reason you shouldn't drive the car hard for a couple of minutes before shutting the engine off too - the other more important reason is so the oil flow to the turbo doesn't stop while the turbo is hot enough to burn the oil in its bearings.

 

 

Yeah fair go guys,

 

I haven't fully explained it tbh, what I'm on about is when the car kicks in an active but you are mid journey so it then becomes a passive but you can feel the engine feels different to when there's no re-gen going on,

 

Hope that reads a bit clearer this time :beer: