Thread: Ins and Outs of DPF. Not all is as it seems.

Originally Posted by Grumbles

I've been bouncing around the different brands of new 4x4s in an effort to make a buying decision. I have been hobbled by the lack of interest to my inquiries from sales people. Much of my use includes short runs and lots [most] of slow bush driving in the High Country.

Of concern to me was the lack of petrol engined 4x4s available to choose from. Petrol is always my first choice if I have one. The over whelming majority of new cars are diesel with a DPF. Every one speaks of the need to take the car for a highway run of more than half an hour at minimum 80KPH at regular intervals or when a little red light comes on....not always practical though.

I began looking at DPF operation and slowly the lights came on when it was explained to me. Note before reading below that it is specifically about Mitsubishi products.

The DPF in the 2021 NX Pajero is an open type DPF consisting of two passages with only one passage passing through the DPF filter, it doesn’t have regeneration control by an ECU, so it can only do passive type regenerations. Forced regenerations or maintenance isn’t required

The 2021 Pajero Sport is EURO5 compliant having a closed type DPF that filters all exhaust gases through the DPF filter. This system does carry out passive and active regenerations and is constantly monitored via the engine ECU through a variety of sensors. This system doesn’t always require long highway drives to carry out regenerations, it just needs to be up to operating temperature, above 40km/h and the particulate matter inside above a predetermined level.
It seems there are 3 DPF types - full regeneration burn type.

- the hybrid type as above.
- the passive no regen burn type.

Before this I had no idea that not all DPFs are the same. It certainly removed any concerns I harbored about owning a diesel 4 x 4...at least a Mitsubishi one.

In all my web reading of all manufactures - spec sheets, reviews, tests, owner reviews/complaints etc - not one mentioned that all DPFs are not equal. In fact there was a common theme of the need for regen burns and for expensive dealer forced regen burns.

It does make me wonder about the DPFs fitted to other manufacturers cars. What type are they?

DPF isnt your only concern, you also have the EGR to deal with, been on CRD since Euro4 . I'll never buy another diesel, Petrols are more reliable nowadays.

Originally Posted by goingbush

DPF isnt your only concern, you also have the EGR to deal with, been on CRD since Euro4 . I'll never buy another diesel, Petrols are more reliable nowadays.

Agreed re the EGR but it won't immobilize you on the side of the road. The DPF will and may cost a heap to have the dealer deal with it.The EGR is a long term issue and doesn't need an immediate visit to the dealer to clean.

But what new petrol 4x4 are you going to buy? Apart from Range Rovers and Jeeps what else new is there to buy? Sweet nothing except for Chinese offerings and by no stretch are they main stream 4x4s. I couldn't find one mainstream new petrol ute or wagon for sale.

Are they still selling the Y62 Patrols or have they gone the way of the dodo too?

Y62 Patrol...yep...still available but only with 5.6 litre petrol engine. My bad though Cripes.....totally forgot about the big Nissan. Thanks for the reminder.

Depending on the time table; the ineos grenadier is said to launch next year and it has both a diesel and petrol option. Assuming they will both be available down under...

Cheers,
-P

Originally Posted by Grumbles

..... The over whelming majority of new cars are diesel with a DPF. Every one speaks of the need to take the car for a highway run of more than half an hour at minimum 80KPH at regular intervals or when a little red light comes on....not always practical though.

.....

This is the common thinking, but I don't think it's explained as correctly as it could be.

I think the actual idea is that the diesel motor in this instance(with DPF) needs some high speed running for about an hour, not so much for it to sit at 80k/h on a highway for an hour.

So if you're into bush territory at slow speed work, then I don't think the impracticality of 'running at 80k/h for an hour on the highway' .. running in low range say at about 3k RPM is about the same idea.

A couple of years ago we changed the DPF fluid in my dads HDi Peugeot, and I found some info that said we needed to do a highway run for an hour at high RPM(not so much at a specific speed).

It just needed constant high RPM running at about 2500-3000RPM to help clean out the DPF filter. The alternative to running it in said manner on the highway was to have it sitting in a well ventilated area and idling at 3000RPM for an hour or so while the DPF fluid did it's burn off thing.

Originally Posted by Grumbles

Agreed re the EGR but it won't immobilize you on the side of the road. The DPF will and may cost a heap to have the dealer deal with it.The EGR is a long term issue and doesn't need an immediate visit to the dealer to clean.

But what new petrol 4x4 are you going to buy? Apart from Range Rovers and Jeeps what else new is there to buy? Sweet nothing except for Chinese offerings and by no stretch are they main stream 4x4s. I couldn't find one mainstream new petrol ute or wagon for sale.

DPF's can strand you - have had the Hilux towed because of this and it's gone into limp mode multiple times because of it. It was only after the tilt tray visit to the dealer they finally agreed to replace it. It’s doubtful I’d buy a modern diesel now either - but I’m not in the market for a new 4WD but a work car, which will be petrol.

I found this video to be very informative about DPF's, EGR's and oil dilution issues. It was linked in a thread on AULRO several years ago.

Understanding Diesel DPF Regeneration - YouTube