[chrisuk]

Last year on holiday on the Isle of Mull, my DPF light came on twice in 500 miles, each time I drove at 50 mph for 20 miles (difficult on Mull) and it went out. It has not come on since after covering about another 6k miles. OK. But if it does come on and won't go out I understand it goes into Limp Home Mode. If this happens how far can you drive like that, does it do any harm? I've seen references to people saying the revs are limited to 3000 rpm, but that infact is reasonable in a short term.
My reason for asking is that we are off to Mull in 12 days time for 3 weeks and the nearest dealer is in Dumbarton, 2 hours drive away + one expensive ferry. Would it be a recovery job on the back of a truck?
I think the problem on the island is the low average speed with lots of stops to view the scenery / birds. Any car should be able to do that! I'm also a little suspicious of the fuel. My dealer simply admits it is a problem with short journies and they can not do anything. Its being serviced on Monday and will tackle them again.

 

[chrisuk]

The AA articicle is interesting. Before I was aware of the problem I was very pleased with the XTs low speed torque and liked tootling around at low speed low revs when on holiday. since then I have tried to keep the revs over 2000 and as often as possible take the revs up to peak revs. Fuel consumption has dropped about 4 mpg. So much for green ideas.
The catclean does not seem to mention DPFs anywhere, I suppose the effect on the Cat is very similar. I am generally reluctant to use additives on a car still in warrenty. I have still got a couple of bottles of Millers from my privious car but am reluctent to use it even though it does specifically say OK for DPFs. I realise Millers is a different type of product.
If it was not the fact that I tow a caravan I would not now buy a diesel.

What about the Limp Home mode?

 

[Umbongo]

I was reading about this yesterday and it does say that you have about severn times of the light coming on and you being able to clear the DPF warning light. Failure to complete the regeneration in one go means the regeneration aborts and your back to square one, it should go through about seven approx, regeneration attempts before finally bringing on the EML light and that's when Dealer regeneration with the Nissan Consult is required together with oil and filter change so you should not drive the vehicle if you can't clear the DPF warning light and the engine management light comes on. I have some info from the manual if you want it I'll post it up here.

 

[kelba1946]

If you want to clean out your system try BG244, these products are used extensively in the US during routine servicing. First used it in my Cherokee there was a significant improvement in the engine smoothness and fuel consumption improved. Improvements were maintained long term, now use it once a year in my X-Trail.

 

[chrisuk]

I must admit to being dubious about using additives, esp. on a car in warrenty. This weekend I have had to do about 350 fast motorway miles which I hope will help.
What is not clear to me is, soot will build up especially is the engine is cold and / or poor fuel, fast motorway use will not produce much soot, but, will fast motorway use burn off the soot accumulated when slow running?
Taking the AAs comments into mind, I made sure that some of my motorway miles were done in 5th rather than 6th to really give it a blast. I'm working on the premise that it is best to keep the revs well over 2k (once the engine is warm)
I will discuss with my dealer tomorrow when it goes into service, but frankly I don't think the average dealer knows that sort of detail.
Friend has recently bought a Mazda 5 with DPF, on those you only have to drive above 25mph and 2500 rpm. 50mph is rediculus. I'm concerned about remote islands, but what about if you travel in the London area?

 

[Umbongo]

This is what it says in the T31 service manual.

DPF Regeneration.
View attachment DPF Regeneration.pdf

Note: If you have difficulty viewing pdfs online, download and install the most current version of Acrobat Reader. Free Download available at http://www.adobe.com.

 

[chrisuk]

Thanks Umbongo, I can't say I understand much I suppose with the right computer attached to the car I might make more sence but not for us amatures. The single line diag is interesting as it shows a differential pressure switch across the filter which is like how we detect flow in industry. I saw on the Aussie XTrail forum how some were wondering how to tap into this signal to the ECU to measure the degree of blockedness. Now that would be a useful guage on the dashboard.

I have just got back from Nissan - Kettering where it had the second year service, they told me that you can drive in excess of 3000 rpm to clear the filter when the DPF light is on instead of the handbooks 50mph +. This is a lot easier / safer on a small island / dence city traffic.
They also told me that driving hard generally will reduce the carbon in the filter. So much for "green" DPFs.

 

[Umbongo]

Thanks Umbongo, I can't say I understand much I suppose with the right computer attached to the car I might make more sence but not for us amatures. The single line diag is interesting as it shows a differential pressure switch across the filter which is like how we detect flow in industry. I saw on the Aussie XTrail forum how some were wondering how to tap into this signal to the ECU to measure the degree of blockedness. Now that would be a useful guage on the dashboard.

I have just got back from Nissan - Kettering where it had the second year service, they told me that you can drive in excess of 3000 rpm to clear the filter when the DPF light is on instead of the handbooks 50mph +. This is a lot easier / safer on a small island / dence city traffic.
They also told me that driving hard generally will reduce the carbon in the filter. So much for "green" DPFs.

Chris, your supposed to be saving planet by driving less :lol:

Drive 5 miles less a week

 

[chrisuk]

Its a great car to drive not admire on the drive!
Thinking of that, I spent some time waiting at the dealers for my car today looking at the Nissan cube, is it a joke?