DPF software removal and remap

One of the guys on the English forum has been working on a similar project to remove the mini and regen cycles. I have sent an email on map price.
Software removal is $560 and ECU has to be sent to England.Could be 2 weeks without it.
Could this be the answer to white smoke problem?
May even improve fuel economy.
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I am looking at doing the same thing - you can buy a spare ecu from wrecker, send the spare away to get re-mapped then plug it in - when you go for a service then just plug your original back in with no warranty issues ( I'm pretty sure the manufacturer has security in place to tell if the ecu has been messed around with)

I don't believe the ecu does any regen or mini regen cycles unless the sensors on the dpf tell it to(there is a pressure sensor before and after when it detects pressure difference it intiates a regen cycle, there is also a temp sensor to monitor temp during regen as it gets bloody hot) this is all done to keep nox emissions down as new diesel engines run lean and hot which causes excessive nox.To lower nox they need to make the engine run rich - impossible on a diesel engine as the more fuel you inject the faster it goes (no throttle body)however they do achieve this by injecting fuel on the exhaust stroke but this causes excess soot and smoke etc hence instaling a dpf to catch this excess soot and then burn it every so often with a sensor initiated regen.

Just hollow out the DPF and leave all sensors as they are and itwill not throw error codes just will never go into regen mode.
ecu remap is the only way to maybe delete this extra injection towards the exhaust stroke to get better fuel economy.

There is a lot of theries currently going on regarding the DPF. I myself was posting a lot regarding DPF and trying to work out theries on what is going on but I now feel that I am very confident n what is going on.

1. On navara's fittted with DPF nissan is using DENSO technology where there are 5 injection cycles per combustion - look at this link - http://www.globaldensoproducts.com/em/dem/crs/solenoid_injector.html , http://www.densoheavyduty.com/pdf/How the Common Rail System Works.pdf , there are many other links and info and oher manufacturers doing exactly the same with CRD and Denso are now going to be injecting up to nine injections per cycle with their latest technology. I think with the navs somewhere along the lines the post injection may be injecting way too much compared to other cars using the same technology for whatever reason. ( maybe to try and prevent the DPF from clogging up too soon??)

2. There are two post injection cycles which are soley responsible for the pollution control i.e DPF filter The injection post combustion is to increase exhaust temps to burn off excess soot.

3.There is an O2 sensor after the DPF which monitors the exhaust gas - The exhaust gas must be rich(ie no oxygen) for the Cat Converter to work effectively and to keep the exhaust temps high to try and reduce soot buildup in DPF. This is done by injecting fuel on exhaust stroke.

4. There are no "mini" regen cycles going on - The extra fuel is being chewed up with the 2x post injection cycles. The only regen that happens is when the pressure sensors ( one before the DPF and one after the DPF) register a higher pressure in the front of the DPF to the back of the DPF which means the DPF is getting blocked - the ECU then triggers a regen cycle to try and burn off the excess soot and clean the DPF. depending on driving habits and conditions but will get more frequent the older the car gets as I dont think the regen will clean out the DPF 100% every time.

5.By installing a DPF delete pipe or simply smashing out the core of the DPF does give you about an extra 1-2 L/100km on fuel economy but you cant really break the 12.5L/100km barrier due to the two post injection cycles which are "always" being injected. ( I had a 2007 navara auto which I always got about 10-10.5L/100km which had no DPF)

6.You need to leave the O2 sensor in place because it detects how much O2 is in the exhaust - as the engine wants an O2 depleted environment if you take it out of exhaust and it goes in fresh air the ECU will pick up the O2 and thinks shit I,m too lean inject even more diesel during the post injection cycles - hence the white smoke ( unburnt diesel) a lot of guys were experiencing.

7.Don't remove DPF while your car is in regen cycle. Once triggered it needs to meet a whole lot of set perameters such as temp v time etc - so if you install a delete pipe while your car was in regen mode and it had not completed the regen then the exhaust temp will never reach predefined temp (as the temp sensor is in front of the PDF - now that a delete pipe is fitted gases will flow straight through and build up the heat) and will stay in regen mode until it does so. Wait till the regen is over then do the delete pipe.

8.I have found another link - http://www.biodieselmagazine.com/articles/2290/understanding-the-post-injection-problem/
which industry are concerced about the post injection cycles washing the walls of the cylinder thus diluting your oil with diesel resulting in drastically reduced engine wear - again Nissan in thier wisdom did not want to install a 5th injector in the exhaust due to cost but instead relied on the normal injectors to administer the post injection cycles. Guess what the new v6 diesel navara has a 7th injector to take care of this ( prob cause it is a renault not nissan engine) there are plenty of other links around sharing the same concerns!!

9. The only way to get rid of these two post injection cycles is with a ECU remap.

I am taking a gamble and getting my ECU remapped to see if they can delete these two post injection cycles.Apparently it can be done but will have to wait and see!!

I might also ad that I have a 2010 STX auto Thai Build and It is stated as Euro 3 Compliant - however even the 2006/2007 model navara "is" Euro 3 compliant so it appears that they were testing their "new" emission technology out way before it was required ready fro Euro 4 requirements- I think the DPF started to come out on 2008 models!!

I hope this clears up all the controversy surrounding the usless DPF that was meant to reduce emissions but you actually create more pollution by using 30-40% more fuel in the process!! at our expense!!

Very interesting stuff, have thought along the same lines.
Thanks for sharing your research results, let us know how the remap goes for you.

So how do u know when the injection cycle is completed or even underway?

The ECU knows when the cycle should start and end by examining the Crank Angle Sensor (CAS) located on the crankshaft.

One of the interesting points above is the exhaust temperature - it reads like the car knows what the temp is in the DPF, which means we should be able to pull post-turbo EGT from the ECU without an additional probe! That won't be as accurate as a pre-turbo probe because the turbo reduces the temp by 150-200C, but it's more than nothing.

I think I'll do some querying of my ECU and see if I can find the PID for this sensor.

theres not temp sensor in them.
ecu most likely works it off a map, most likely based on fuel and air inputs. it guesses the temp.
thats probably why people have so many problems after driving through creeks with them. dpf gets water cooled.

My Q is then, if I were to remove the dpf (which I am seriously considering) how do I know when the burn has taken place

If you remove the DPF and the sensors remain equalised a burn should never happen. If it DOES happen, you should see a lot of white smoke from the back of your vehicle.

SLAC said:

My Q is then, if I were to remove the dpf (which I am seriously considering) how do I know when the burn has taken place

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when the regen happens the dashboard light should show up ( looks like a puff of smoke on the top r/h corner) that tells you when a regen is happening.

make sure that all the sensors are still in place and it is critical that the O2 sensor ( biggest sensor on the rear just behind the DPF) is put back in exhaust other wise the ECU will measure high O2 readings and fuel up the exhaust via post injections and you will blow white smoke.

I have had a straight flow through DPF for 35,000km now and not one regen and no problems.

apcconstructions said:

I have had a straight flow through DPF for 35,000km now and not one regen and no problems.

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So if I'm reading this correctly you have removed the inner of the DPF and left ALL the sensors in there place, yeh?
How did you remove the inner part plz?

Well done and said APC!!

That is also the first time I have heard the fuel figures from an auto pre DPF, this is what I have been going on about but have been shut down by a certain few on here, I wanted to compare my auto fuel consumption (with a DPF) to another pre 2008 without a DPF and wow 10 - 10.5 LPHK!! The best I can get is about 12-12.5 and thats driving like Miss Daisy.

How could they have introduced this in the interest of reducing pollution when in turn we are consuming more fuel in the process.

Looks like you have spent a fair bit of time researching this, again well done and I look forward to hearing the results after the ECU remap.

jjohn said:

So if I'm reading this correctly you have removed the inner of the DPF and left ALL the sensors in there place, yeh?
How did you remove the inner part plz?

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I unbolted the dpf and then used a 25mm dia masonry drill bit with a drill ( only cause I had a nice long one handy - about 450mm lng) I then drilled out the core from both sides and then just used a star picked to help widen out the hole( it is like a honeycomb structure and the material is similar to the fire bricks you get in the fire place ( like a lightwieght aerated autoclave brick). Then bolted the unit back in with all existing sensors in place.

From the outside - its the factory DPF but without the stupid core. Only thing is it will give off some balck smoke when you put the foot down - exactly like the previous models and like the current manuals!!


Note: Make sure you take the sensors out while yo hollow out the dpf so you don't bugger them, then screw tham back in once you have finished!!

Arty_74 said:

Well done and said APC!!

That is also the first time I have heard the fuel figures from an auto pre DPF, this is what I have been going on about but have been shut down by a certain few on here, I wanted to compare my auto fuel consumption (with a DPF) to another pre 2008 without a DPF and wow 10 - 10.5 LPHK!! The best I can get is about 12-12.5 and thats driving like Miss Daisy.

How could they have introduced this in the interest of reducing pollution when in turn we are consuming more fuel in the process.

Looks like you have spent a fair bit of time researching this, again well done and I look forward to hearing the results after the ECU remap.

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Yea there have been a few guys with not much up top talking about fuel economy.The DPF models deffinately chewed the juice compared to the previous model and by at least 50% more fuel - driving habits have nothing to do with it. I have a farm 250km away and my 2007 model always got 10 - 10.5 where as the 2010 model could not break the 14.5L mark no matter how careful I drove. Interestingly I currently have a ford territory CRD (hire car) while my wifes car is getting repaired. It has a 2.7L v6 turbo diesel auto( ford borrowed it from the range rover from 6 years ago). It currently gets 10L/100km city driving and 8.2L/100km country driving.

* another thing I also picked up and I don't know if it only applies to WA but using BP ultimate diesel I loose a good 50-80km per tank compared to other diesel fuel( a few other mates have noticed the same thing). I think while it may be better for you engine parts ( it is refined more and doesn't clog up filters etc) the refining process removes a few more of the carbon chains in the fuel and therefoe there is less energy in each litre of fuel compared to just a std diesel. ( same thing happens with petrol - a high octane fuel is refined more and has less potential energy however cars that are made for high octane fuel actually have a higher compression ratio which helps bring back the lost power. - the higher octance allows for a higher compression without pre detonation) That is why some of the high performance cars like nissan GT will ping if you use std petrol!!

apcconstructions said:

I unbolted the dpf and then used a 25mm dia masonry drill bit with a drill ( only cause I had a nice long one handy - about 450mm lng) I then drilled out the core from both sides and then just used a star picked to help widen out the hole( it is like a honeycomb structure and the material is similar to the fire bricks you get in the fire place ( like a lightwieght aerated autoclave brick). Then bolted the unit back in with all existing sensors in place.

From the outside - its the factory DPF but without the stupid core. Only thing is it will give off some balck smoke when you put the foot down - exactly like the previous models and like the current manuals!!


Note: Make sure you take the sensors out while yo hollow out the dpf so you don't bugger them, then screw tham back in once you have finished!!

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So you didn't remove all of the biscuit you made a hole through it? Sorry!!

jjohn said:

So you didn't remove all of the biscuit you made a hole through it? Sorry!!

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Yea just made a like a 21/4 inch hole straight through the middle - same as the exhaust pipe diameter so it is essentially a straight through exhaust now. to try and remove the complete biscuit will be a nightmare and will prob achieve nothing anyway??

Thanks heaps eh.
Amazing that you have had no white smoke as some others have, although they replaced the DPF with a delete pipe that had all the sensors connected. Can't say what the difference would be.
?????????

I must be a lucky one then... 08 dual cab auto I am getting 11.5-8ltr per 100km.... Get 580km for 67-8ltrs. Thats being a bit of a lead foot as well..

Still not impressed with those figures though!
My previous 04 short wheeled base ford transit got 650km fully loaded (x plumber) towing a 1.5t excavator up the blue mountains... Without excavator 700kms and, with van completely empty 800+

jjohn said:

Thanks heaps eh.
Amazing that you have had no white smoke as some others have, although they replaced the DPF with a delete pipe that had all the sensors connected. Can't say what the difference would be.
?????????

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I cant see any difference - DPF with core or delete pipe without core - the only sensors used are pressure differential sensors, temp sensor and O2 sensor. The ECU can not tell if there is a core in there or not!!

I think they replaced the pipe when the car was in regen mode and it had not finished - that would blow white smoke as the extra diesel used to burn up the soot in the dpf would be just blowing straight out the exhaust rather than getting cought up in the DPF brick and heating up the DPF core???

Once the DPF had been removed there was no way for the predefined temp to be reached so the ECU would just keep chucking out diesel trying to get the temp up to complete the regen cycle. - The pressure sensors initiate the regen and also tell the ecu when the pressure equalises (which means clean dpf) , the temp sensor lets the ECU know when the right temp has been reached and I would also say to prevent melt down and then the O2 sensor keeps the exhaust rich with fuel. I believe that once a regen cycle has started it can only turned off once the pressure sensors equalise and a predifined temp is reached as the DPF needs to get over 600 deg to burn out soot.

I have also driven around without the O2 sensor connected and nothing happens - except you get a fault code show up.

I know some guys used the delete pipe and left the o2 sensor out of the exhaust which straight away the ECU will pick up way too much O2 and try and bring it down by injecting more diesel = white smoke

Maybe go for a 100km drive on the freeway sitting on 100kmhr to make sure that there is no regen happening and everything is clean and happy!!!

apcconstructions said:

I cant see any difference - DPF with core or delete pipe without core - the only sensors used are pressure differential sensors, temp sensor and O2 sensor. The ECU can not tell if there is a core in there or not!!

I think they replaced the pipe when the car was in regen mode and it had not finished - that would blow white smoke as the extra diesel used to burn up the soot in the dpf would be just blowing straight out the exhaust rather than getting cought up in the DPF brick and heating up the DPF core???

Once the DPF had been removed there was no way for the predefined temp to be reached so the ECU would just keep chucking out diesel trying to get the temp up to complete the regen cycle. - The pressure sensors initiate the regen and also tell the ecu when the pressure equalises (which means clean dpf) , the temp sensor lets the ECU know when the right temp has been reached and I would also say to prevent melt down and then the O2 sensor keeps the exhaust rich with fuel. I believe that once a regen cycle has started it can only turned off once the pressure sensors equalise and a predifined temp is reached as the DPF needs to get over 600 deg to burn out soot.

I have also driven around without the O2 sensor connected and nothing happens - except you get a fault code show up.

I know some guys used the delete pipe and left the o2 sensor out of the exhaust which straight away the ECU will pick up way too much O2 and try and bring it down by injecting more diesel = white smoke

Maybe go for a 100km drive on the freeway sitting on 100kmhr to make sure that there is no regen happening and everything is clean and happy!!!

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If you followed the threads regarding this topic closely you would see that the only people that have had problems with white smoke are the guy's that have removed both the DPF and the factory CAT.
If you remove only the DPF and replace sensors then you will have no problems.
If you remove both DPF and CAT then you start to have problems. Even fitting an after market CAT still doesn't stop the problem.
Some guy's have had a little success by spacing the O2 sensor out of the pipe but it's a bit hit and miss so the best option is to either gut out the DPF or replace but leave the factory CAT.

Also just for your info my DPF'd 07 with just shy of 200,00km's and 700kg in the back constantly returns low 11's open road running and I if I take it real easy I can get as low as 10.2