That bastard DPF light

[merchant]

Hi all

My bastard DPF light came on again yesterday and i freaked. The last time if came on was about 18 months ago and i was stuck in the Pilbara for a week and it cost my near on $350 to have it fixed and Nissan wouldn't cover it.

I just returned from a 3000km trip so couldn't work out why it came on. Anyway, i was on the way to the boat ramp so we chucked the boat in and 3 hours later came back and started the car up. Low and behold no DPF light. Thank you to the little fairies who fixed it while i was away.

Didn't catch a bloody thing either.

 

[Old.Tony]

It sounds to me like you need to speak to Robert at ChipIt and get him to freight you a DPF Delete pipe. It's now something we are very, very seriously considering and we haven't had a thing go wrong with ours, in spite of towing it through the middle of Australia and a good stretch of soft sand pulling the van along the Ernest Giles Road.

Yours could be just a slightly off-spec pressure sensor too, it's hard to tell without being able to swap out bits and test them against known good ones.

 

[merchant]

It sounds to me like you need to speak to Robert at ChipIt and get him to freight you a DPF Delete pipe. It's now something we are very, very seriously considering and we haven't had a thing go wrong with ours, in spite of towing it through the middle of Australia and a good stretch of soft sand pulling the van along the Ernest Giles Road.

Yours could be just a slightly off-spec pressure sensor too, it's hard to tell without being able to swap out bits and test them against known good ones.

There are a nuisance. And will definitely change the DPF out once the warranty expires. Not long now.

It is possible i got some bad fuel on my recent trip and this caused excess soot build up. But who knows with these things. That's would Nissan would blame without knowing anything else. I started the car in the morning, drove to the servo about a Km away, let it isle while a friend filled up the boat and then i drove off. It would have idled no more than 4 minutes. The light came on as soon as i pulled out of the servo.

I'll monitor it over the coming weeks. It's going on a dyno to test the Ebay power chip i put on it. So i'll speak to the experts about it.

PMG Karratha still dosen't have a Consult II machine so if a forced burn is needed i have to wait for them to borrow one from Port Hedland. Fantastic!

 

[Old.Tony]

If the light's gone back out I'd say it's probably managed a regen on its own and fixed itself.

You could always try idling it for 10 minutes and see what happens.

 

[Downsized]

DPF light.

I had the light come on after I connected my exhaust jack (bullbag).

After a restart it went out.

I think the sensors may be a bit too sensitive. I have the DPF delete pipe and like you will wait untill the warranty expires before putting it on.

 

[Pete22]

I had the light come on after I connected my exhaust jack (bullbag).

After a restart it went out.

I think the sensors may be a bit too sensitive. I have the DPF delete pipe and like you will wait untill the warranty expires before putting it on.

Yep...one of those thar delete pipes has just moved to the top of my shopping list....and will be fitted once the warranty expires.

 

[tweak'e]

poor fuel, driving at low speed (ie low exhaust heat) and also if your chopping in/out of gears (or torque converter lockup come on/off) is enough to generate more soot.

the other thing is to limit soot production. eg cut down the amount of EGR (blanking plate with hole drilled in it). theres also some talk on 2 stoke oil in the fuel that won't clog the dpf and also because it helps burn the fuel cleaner you produce less soot.

 

[Pete22]

poor fuel, driving at low speed (ie low exhaust heat) and also if your chopping in/out of gears (or torque converter lockup come on/off) is enough to generate more soot.

the other thing is to limit soot production. eg cut down the amount of EGR (blanking plate with hole drilled in it). theres also some talk on 2 stoke oil in the fuel that won't clog the dpf and also because it helps burn the fuel cleaner you produce less soot.

If you have some time on your hands there is a very lengthy discussion about the use of 2-stroke oil here: Freel2.com - View topic - 2-stroke oil and diesel

 

[tweak'e]

been there
been running 2 stroke for a fair while now. however i don't have cat or dpf so theres nothing for it to block up. theres a bit of a debate if 2 stoke oil is safe for dpf or not.

 

[Old.Tony]

I've used 2-stroke in mine. It's better than Chemtech Diesel Additive which does sweet FA for my car. My DPF is still intact, too. I will return to Castrol Activ 2T as soon as I'm finished this bottle of the Chemtech stuff.

The only thing to make sure of is to use JASO-FC rated oil. FD is even better but doesn't give you the savings. FC is low enough in ash content to not impact on the DPF.

However, I suspect we're opening a can of worms here.

 

[tweak'e]

most of the FD you can't use because they are synthetic oil. some of the FC's are to but none of the FB's are.

 

[D40 AUTO]

i have had my truck for allmost 4yr now an that light has never come on yet

 

[Old.Tony]

i have had my truck for allmost 4yr now an that light has never come on yet

I would imagine it's actually an uncommon occurrence for it to happen too.

The DPF has to show signs that it's blocked. This is measured by two pressure sensors - one before the filter, and one after. If there's enough difference, the ECU then looks for the conditions to conduct a regeneration cycle.

The regeneration cycle is performed if the engine rpm is greater than 1600, if the engine temperature is normal (measured by the radiator, 95C), if the engine load is not high (various mechanisms in the gearbox can determine this) and the O2 sensor in the DPF pipe shows that there is enough unused oxygen in the exhaust for the cycle to actually be successful.

Most of the time, we happily drive our cars around and meet these criterion without even thinking about it. It's when they're worked hard (offroading, extensive towing on poor surfaces etc) that they block up without the opportunity to clear themselves.

 

[Pete22]

I would imagine it's actually an uncommon occurrence for it to happen too.

The DPF has to show signs that it's blocked. This is measured by two pressure sensors - one before the filter, and one after. If there's enough difference, the ECU then looks for the conditions to conduct a regeneration cycle.

The regeneration cycle is performed if the engine rpm is greater than 1600, if the engine temperature is normal (measured by the radiator, 95C), if the engine load is not high (various mechanisms in the gearbox can determine this) and the O2 sensor in the DPF pipe shows that there is enough unused oxygen in the exhaust for the cycle to actually be successful.

Most of the time, we happily drive our cars around and meet these criterion without even thinking about it. It's when they're worked hard (offroading, extensive towing on poor surfaces etc) that they block up without the opportunity to clear themselves.

Mine has only come on twice...once on the Gary Highway out near Vievers Crater and the second time on the Hume Highway just south of Gundagai. The first case I believe was due to travelling at speeds of around 25 kph for 3 days....locked the auto in 1st, kicked the revs up for about 10 mins and the light went out. Would have been interesting trying to get a dealer burn done at the Well 33 shop or in Warburton . The second case I still can't figure....I'd filled up with diesel at the big shell servo just on the north side of Albury and was towing my camper (~1.2 tonne at the time) and travelling at highway speed limit of 110kph the blood light came on. Had a coffee at Gundagai to contemplate the situation and re-read the book....took to the road again....turned O/D off and took her up to 110 kph again - after about 15 minutes the light went out....go figure!

 

[Old.Tony]

I guess there's always the chance that soot could impact on the pressure sensors too. Since the DPF is designed to catch soot, the upper sensor could easily have soot in it, and the latter not - there goes a pressure differential. The regen cycle could have cleared the sensor, removing the fault and turning out the light.

Have you done the EGR mod? There's 20 minutes that will give you lasting value.

 

[tweak'e]

....... if the engine load is not high (various mechanisms in the gearbox can determine this)

throttle position is more common.

Most of the time, we happily drive our cars around and meet these criterion without even thinking about it. It's when they're worked hard (offroading, extensive towing on poor surfaces etc) that they block up without the opportunity to clear themselves.

its not working them hard that the problem. more often than not its because they are not worked hard. sitting at cruise, light load, which gives low EGT's (lack of heat to regen naturally) and high soot production due to egr system.
the on/off nature of the auto gearbox compounds it. especially if OD or lock up clutch is going on/off all the time. each change means another puff of soot the dpf filters.

heavy acceleration gives lots of heat and minimal soot so it tends to clear itself.

so being light footed usually means dpf goes into regen mode and burns lots of fuel. you can't win !