Hi Guys,

I had my Nissan in the workshop the other day getting some performance upgrades (bigger turbo and tuning and the mechanic told me that he thinks my car is producing WAY to much soot. I looked at the exhaust pipe and noticed a fair bit of soot buildup around the tailpipe.

The details are:

2000 Nissan GU Patrol
4.2L Turbo diesel
25 000 ks on bio

I noticed the other day that the car needs a few pre heats to get started when cold ( maybe needs new glow plugs??) and it puffs out a small cloud of black smoke upon starting. There is also a bit of smoke under hard acceleration and when I rev the car (in nuetral) as the engine is spinning down.

About 10 000 ks ago I replaced a IP due to failure which the reconditioner stated MAY have been due to BIO however could also not rule out other causes.

Since my IP failure, I have started testing, testing and retesting my bio to ensure high quality. I found I had some soap still in the bio, but not much. The conversion was also WAY down with it consistently failing the 3/27 test with about 50% unreacted oil. Since this time, I have ensured EVERY batch has passed the 3/27 and I have increased the amount of washing. I have also allowed each batch to settle for a minimum of a week before draining and filtering.

I thought that this increased quality of fuel would have made the engine perform better and I thought, reduced soot output.

What causes this soot? Is it incomplete combustion?

Any thoughts are appreciated.

Thanks

Greg

In the words of Gale Banks, Smoke is power you can see but not use.

Drop a NOS system onto your car. That smoke will clear up nice and good.

The oxygen has been burned up but the fuel has not. Some nitrous gas will add the O2 you need for complete combustion.

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Joe Morgan
Brisbane Biodiesel Site Admin
http://www.brisbanebiodiesel.com

Searching tips using Google - SVO Dual tank systems
SVO, Common Rail and Direct Injection - Vehicles converted to Used Cooking Oil

Put a larger exhaust system on, at least 3 inches. Did that to mylandcruier and it stopped about 95% of the smoke / soot. The engine breathes better and bets better combustion hence less soot. Don't tell me its not producing power beacuse it certainly is, pulls better and the turbo whistle is great. Also only has one small muffler not two large ones. Better economy too as I don't have to push it as hard anymore.

Matt
Your mileage may vary!

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Biodiesel Bandit

Landcruiser 98 B100 (100,000km and still going)
Peugeot 306 xtdt B100
Peugeot 2004 2L 307 HDI Does not like B100

Thanks for the replys guys!

The mechanic told me about the soot buildup issue whilst he was working on it. I definately have not noticed any more smoke since he did the work. I spoke to him today and he assured me they did tune the IP for maximum power/torque, but due to the mechanical nature of my cars injection system it was impossible to have the revs vs fuel ratio exactly right all the time through the rev range and he agreed with you David that a little overfueling while the engine revs down is completely normal.

I am planning on just keeping an eye on things and seeing how it goes. There only seems to be smoke under hard acceleration, on rev down and when I first start up. All these sound normal from what has been said here.

Thanks guys

Greg

Greg there are many causes of excessive smoke. But first you need to know just how much it is smoking and you can't do that from the drivers seat. You need to follow in another car with someone else driving yours, preferably on a UHF radio or hands free so you can instruct them re which gear to be in and how much throttle etc. Once you have confirmed the excess smoke then you can do something about it. I take it that it was smoking before the mods from what you are saying, if it was not then I second what Dave said and you should insist they fix it. They have probably increased the fuel too much or the turbo isn't delivering the air it should be.
If the problem has been there a while then your injectors probably need servicing, the smoke on start up points to that. I would not be going for further mods like Nox or huge exhaust as they are only going to compound problems until you have the fuel delivery sorted.

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Johnnojack
4WD Isuzu Jackaroo 3.1 68,000km on WVO 2 tank home built system 6 solenoids. Mk. 8 version.

I absolutely agree, injectors first, then the IP and the exhaust pipe.

Dave I suggest you go to a cheap exhaust shop and ask for a straight through 3 inch system, you will be surprised how cheap it is. The one for my Toyota came off evilbay and cost only $430. It was beuatifully bent and required just a little adjusting to not rattle. It is amazing, so much so I will be looking at doing same for the little Peugeot 307 too when I get an intercooler for it. Its not for show but effect.

Interestingly the old Toyota system had two large mufflers, this one has one small one and makes hardly anymore noise, lovely note to it in fact.

I am sold on the idea of better combustion and thermal efficiency, letting the engine breath better is a good thing for it and the environment. Less soot, more efficiency, less boot, better fuel economy and happy me.

Have fun
Matt

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Biodiesel Bandit

Landcruiser 98 B100 (100,000km and still going)
Peugeot 306 xtdt B100
Peugeot 2004 2L 307 HDI Does not like B100

So it's a good thing? that exhaust

Does your exhaust smell any different since you put it on? mine does.

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HDJ80 (aka Kiwipete)
Canberra

Excessive soot can be over fueling actually better that white smoke with Dino Diesel

I take it you are running B100

I get a bit of black smoke on startup but that's it....

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HDJ80 (aka Kiwipete)
Canberra

On startup there is a general lack of temperature and hence incomplete combustion and lots of carbon hence black soot. Once up to temp things change a lot. Soot is a sign of incomplete combustion either by overfueling (ie not enough oxygen to oxidise it all) or by bad injection or some other matter like filter restricting air etc etc. Timing too can play a part, so many variables to point to one as the culprit.

Exhaust is great, smell changed a little not as much oil left over so not quite as oily.

Matt

__________________
Biodiesel Bandit

Landcruiser 98 B100 (100,000km and still going)
Peugeot 306 xtdt B100
Peugeot 2004 2L 307 HDI Does not like B100