Sat in traffic this evening the idle sat at 1000 rpm so I'm assuming the DPF was trying to regenerate? Unfortunately we were in stop/start traffic so couldn't do too much about it but it was only Saturday when we were sat on the motorway for 2 hours doing a constant 70, would I be right in assuming we were unlucky and it didn't need to regenerate then but it does now?

Should we take the car on the motorway tomorrow for 20mins as on the way home the idle dropped back to 800 rpm with no warning light etc.

Cheers

What revs does it do at 70? There are problems with DPF cars with 6 speed boxes not getting hot enough at motorway speeds due to lower revs.

If it gets hot enough on the motorway it constantly regenerates without any ECU intervention.

Not sure on rpm at 70 but it's only a 5 speed anyway so should have been high enough for regeneration. Didn't realise it constantly regenerated on motorway, wonder why it's trying to Regen again so quickly?

Your correct in that when it ticks over at around 1000rpm its doing a passive regen and you'll get no lights up. The sign its finished is when tickover returns to normal, so if thats happened its happy days

If you interupt a regen by switching the engine off the fans go flat out as they need to cool the dpf down as it gets hot during a regen and annoy your neighbours, but at that stage it's abandoned the regen and won't just carry on if you start the engine again - you then have to wait for the soot you've already burnt off during the interupted regen to build up again before it triggers another.

Sounds like yours completed its cycle so just carry on as usual.

If you look on suks website theres a bulletin for both pd and cr engine regens. Have a read and it should answer your questions. With crs you just basically carry on driving normally until its finished.

^{Your correct in that when it ticks over at around 1000rpm its doing a passive regen and you'll get no lights up. The sign its finished is when tickover returns to normal, so if thats happened its happy days}

If you interupt a regen by switching the engine off the fans go flat out as they need to cool the dpf down as it gets hot during a regen and annoy your neighbours, but at that stage it's abandoned the regen and won't just carry on if you start the engine again - you then have to wait for the soot you've already burnt off during the interupted regen to build up again before it triggers another.

Sounds like yours completed its cycle so just carry on as usual.

If you look on suks website theres a bulletin for both pd and cr engine regens. Have a read and it should answer your questions. With crs you just basically carry on driving normally until its finished.

 

^{Cheers. The pdf  says to drive at 40mph .... for 10-15 minutes, Is slowing down for roundabouts is OK for does it really have to be 40mph+ for 10-15 minutes without dipping below that for the whole time? Just trying to work out whether a motorway run would be needed.}

 

^{Also we had to stop and switch off engine while the revs were at 1k on idle, when we restarted approx. 15 minutes later the revs were at 1k on idle for a few minutes then dropped to 800rpm again but I dont see how a regen could be successful.}

I'm pretty sure it's just the antistall / start assistant you've experienced. I know for a fact that the ECU would never allow a regen while standing still. Revs will increase to 1000 rpm if you have the clutch pressed.

^{Cheers. The pdf  says to drive at 40mph .... for 10-15 minutes, Is slowing down for roundabouts is OK for does it really have to be 40mph+ for 10-15 minutes without dipping below that for the whole time? Just trying to work out whether a motorway run would be needed.}

 

^{Also we had to stop and switch off engine while the revs were at 1k on idle, when we restarted approx. 15 minutes later the revs were at 1k on idle for a few minutes then dropped to 800rpm again but I dont see how a regen could be successful.}

 

Think your looking at the PD version. the rapid has the CR engine you only really need to drive normally. if you come across slow traffis etc its not a problem, it'll just take a bit longer to perform the regen (I've had this happen myself in my Octy). When you switched off did both fans go flat out for several minutes- as that's the clasic sign you've interupted the cycle

 

Here's the CR version

 

http://www.skoda.co.uk/SiteCollectionDocuments/Brochures/19246_Skoda_DPF_Leaflet_v7.pdf

I'm pretty sure it's just the antistall / start assistant you've experienced. I know for a fact that the ECU would never allow a regen while standing still. Revs will increase to 1000 rpm if you have the clutch pressed.

 

Not true, 1,000rpm at idle is a DPF regen.

 

My PD also used to idle fast during a regen.

 

The higher rpm at idle is to maintain temperature in the exhaust in the hope that the rest of your journey allows the regen to complete. If it doesn't it will simply abandon the regen and try again another day, hence the rpm dropping back to normal.

 

The regen doesn't need to complete in one go. If it gets half way through a regen and the engine is turned off or the driving style doesn't allow for sufficient heat it'll finish it off at the next opportunity.

Dude regen will never happen at idle. Just do a search on Google. Specially not on the new cars. Regen will start when driving above a certain speed which i don't remember right now. If the speed drops below regen will temporarely stop and then continue when the speed reatriction is met again.

Here's some reading:

http://www.skoda.co.uk/SiteCollectionDocuments/Brochures/19246_Skoda_DPF_Leaflet_v7.pdf

http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration

http://www.seatcupra.net/forums/showthread.php?t=263734

If it's started regen it will continue during the journey until completion or the engine is turned off. The car has no idea whether you are going to stop. Hence it runs higher revs at idle as it continues the regeneration.

I am slightly surprised it did an active so soon after a motorway run but I'd just keep an eye on it.

Dude regen will never happen at idle. Just do a search on Google. Specially not on the new cars. Regen will start when driving above a certain speed which i don't remember right now. If the speed drops below regen will temporarely stop and then continue when the speed reatriction is met again.

 

Wrong. Read what "simonsheil" wrote.

 

My Superb Greenline acts in the same way - perfectly normal.

My Fabia used to regenerate frequently when it was new, the rubber burning smell and uneven idle were the clues and sometimes I had no oppotunity to give it the run, it theoretically needeed.

 

The car has now done 35000 miles and I cant remember the last time it regenerated.

Dude regen will never happen at idle. Just do a search on Google. Specially not on the new cars. Regen will start when driving above a certain speed which i don't remember right now. If the speed drops below regen will temporarely stop and then continue when the speed reatriction is met again.

 

This is the beauty of the CR engine (compared to the PD), it is able to regen in slow moving traffic.

 

The regen won't start until certain parameters are met such as speed and engine operating temperature, however if the regen has started and you come to a stop the regen will continue for as long as possible.

 

The parameters on the CR are 23mph and 700rpm. 

 

This is the reason for the high idle when stationary, it is attempting to maintain enough heat in the exhaust to complete the regen.

 

More often than not, especially in the UK and Denmark with its colder climate the high idle alone won't be enough so the regen quits and the rpm returns to normal.

I rest my case then. You never get too old to learn some new things. Thanks guys. I've had the PD engine for too long.. Hehe.