to smoke or not to smoke

[Greg Roles]

yeh Banks is an absolute master.... his diesel drag truck is in the 7's now!!!

yeh cogdoc, where did you get that book? im well and truly interested

HIGHLY recommend both the purchase and the UK seller. The blower book told me a lot about blowers, which I will admit was my "stage 3" idea, but the diesel book kind of destroys that idea....and gives me some new, easier ones!

Whilst about half the book is about US trucks specifically, the same rules apply, but the numerous interviews and the general diesel tuning ideas from the various big shops in the USA is just pure gold.

http://cgi.ebay.com.au/ws/eBayISAPI....m=250362507328

[gregozedobe]

Soot is simply incompletely combusted diesel fuel (too much diesel for the available oxygen). This tends to happen when there is not enough boost (typically at low revs), or the injectors are over-fuelling (typically at full accelerator pedal at higher revs).

As I have said previously, more soot = more diesel not being burnt completely = worse economy (it can also lead to very high combustion temperatures, with disastrous consequences for the engine)

Seeing as soot is just incompletely burnt hydrocarbons, anything that helps efficient burning of all the fuel in the cylinder will likely help reduce soot.

The highlight of the book is interviewing industry leader Gale Banks of Banks performance, one of the guys who started toying with diesels back in the 80's, his take is smoke is that it's TOTALLY UNECESSARY and in fact just a sign of a lack of air / bad tuning.

Quote:

" When you see smoke from a diesel exhaust, it's because it doesn't have enough air to completely burn all the fuel. If it doesn't have enough air, you have to figure a way to get more air into it. Excessive smoking is power you can see, but not use. That is not smart in my book. Any guy who thinks smoking diesel engines are cool doesn't know what he is talking about. "

Good to see I have a supporter everyone respects (sorry, I couldn't resist )

[Transporter]

I'm most of the way through an awesome diesel tuners book from the states, and BOY does it debunk a few myths, I've learnt a STACK. The highlight of the book is interviewing industry leader Gale Banks of Banks performance, one of the guys who started toying with diesels back in the 80's, his take is smoke is that it's TOTALLY UNECESSARY and in fact just a sign of a lack of air / bad tuning.

Quote:

" When you see smoke from a diesel exhaust, it's because it doesn't have enough air to completely burn all the fuel. If it doesn't have enough air, you have to figure a way to get more air into it. Excessive smoking is power you can see, but not use. That is not smart in my book. Any guy who thinks smoking diesel engines are cool doesn't know what he is talking about. "

The editor then explains that in racing applications excess fuel IS added, but the power addition is only small.

The best $45 I have spent on the TDI to date. See "my" thread for a pic.

Or you can modify the signal from the MAF sensor to ECM (lower the voltage with small circuit involving 2 resistors and one potentiometer), ECM will adjust the injected amount of fuel hence reduced smoke from the exhaust.
I've done it when my T5 was new; result was no smoke from the tail pipe.
I removed the circuit after one week of driving.

[gldgti]

Or you can modify the signal from the MAF sensor to ECM (lower the voltage with small circuit involving 2 resistors and one potentiometer), ECM will adjust the injected amount of fuel hence reduced smoke from the exhaust.
I've done it when my T5 was new; result was no smoke from the tail pipe.
I removed the circuit after one week of driving.

why? please explain why you removed it..

[Greg Roles]

Probably cause of the power drop, as he was pulling fuel across the entire rev range. Remember diesels run lean until WOT, and there's no problem in pulling fuel below that, you'll just lose power. At WOT, well, I guess you want the MAF back to normal!

Just a guess, but thanks for the tip Mr T, as if I put in my planned bigger 3" intake pre turbo, my MAF will be reading low in an increased diameter pipe.

Really I think I'll need a proper custom tune to account for it.

[Transporter]

why? please explain why you removed it..

For several reasons:

Without further testing I didn't know what that modification could cause in the long run.

VW technician at the factory and people who made the software for EDC have the reason why they made it that way. Every car/engine is tested, tuned, check and driven for many km's, many adjustments were made before they sell final product. Environment agencies and government are pushing the boundaries with lower and lower emission standards and here I'm with my 2 resistors and potentiometer and I solved the problem for them or not? If it were that simple and safe it would be done at the factory.

I think that you cannot adjust the injected quantity of the fuel any better than it is done already (at the present time), we wouldn’t need the DPF would we?

I prefer long engine life and good fuel economy before any increase in the performance.

[Greg Roles]

True mate, but if you look at a factory tune, which is ALL about engine safety in various climates and driver intelligence, and an aftermarket tune, the air fuel ratio line on a factory tune is all over the place, whereas a chip tuner smooths it out specific to the environment. Personally I believe this to be a lot of what you "feel" when you get a chip, simply more accurate air fuel for better response, and some of the limitations removed.


Air fuel starts top left - my stock tune....




Jaymz's early version superchipped TDI, notice the much smoother fuel line, and before you all start, it was both an early tune, hot and the AC was on, thus not a big number difference, but MAN it was night and day to drive...

Notice too the stock TDI leans out up top, but the tuned one doesn't!

[Transporter]

Probably cause of the power drop, as he was pulling fuel across the entire rev range. Remember diesels run lean until WOT, and there's no problem in pulling fuel below that, you'll just lose power. At WOT, well, I guess you want the MAF back to normal!

Just a guess, but thanks for the tip Mr T, as if I put in my planned bigger 3" intake pre turbo, my MAF will be reading low in an increased diameter pipe.

Really I think I'll need a proper custom tune to account for it.

I didn't take it to a race track and in the normal driving condition I couldn't tell if it loss the power or not.

The smoking at that time was due more to our poor quality of the diesel and it was reduced by 50% from 1/1/06.

[Transporter]

True mate, but if you look at a factory tune, which is ALL about engine safety in various climates and driver intelligence, and an aftermarket tune, the air fuel ratio line on a factory tune is all over the place, whereas a chip tuner smooths it out specific to the environment. Personally I believe this to be a lot of what you "feel" when you get a chip, simply more accurate air fuel for better response, and some of the limitations removed.


Air fuel starts top left - my stock tune....

At the expense of the predicted engine life.
Don't you think that with tougher emission standards they would would do a better job in the factory?
I mean in reducing the soot from the exhaust not in getting more power. Manufacturers can tune that 2.0L TDI for more power, but will the engine last? I don't think so.

[Greg Roles]

It's kinda hard to have a one tune fit's all with countries from desert to ice, humid to dry, sea level vs mountains. I know VW have a hot or cold climate option, but no, I don't believe the car comes from the factory in an optimal tune for where I live. As an example, cars down south ALWAYS have better figures, because of the humidity in the air in QLD, and thus less oxygen per stroke. VW tunes are a compromise, and cars are very often tuned below optimal to safeguard against poor fuels, stupid owners, environmental factors and of course, to ensure the engine lasts longer than warranty. I'm looking for POWER.

Personally I believe there's always room for improvement, and not necessarily at the expense of reliability. My current plan of adding a water intercooler will drop the thermal load on the engine and turbo, and if anything will decrease the engines stress. VW don't go water because it's FAR cheaper, simpler and sufficient in stock tune to fit an Air to Air.

But hey, I'm obviously not worried about longevity, otherwise I'd leave the bonnet for the mechanic.

[Transporter]

It's kinda hard to have a one tune fit's all with countries from desert to ice, humid to dry, sea level vs mountains. I know VW have a hot or cold climate option, but no, I don't believe the car comes from the factory in an optimal tune for where I live. As an example, cars down south ALWAYS have better figures, because of the humidity in the air in QLD, and thus less oxygen per stroke. VW tunes are a compromise, and cars are very often tuned below optimal to safeguard against poor fuels, stupid owners, environmental factors and of course, to ensure the engine lasts longer than warranty. I'm looking for POWER.

Personally I believe there's always room for improvement, and not necessarily at the expense of reliability. My current plan of adding a water intercooler will drop the thermal load on the engine and turbo, and if anything will decrease the engines stress. VW don't go water because it's FAR cheaper, simpler and sufficient in stock tune to fit an Air to Air.

But hey, I'm obviously not worried about longevity, otherwise I'd leave the bonnet for the mechanic.

Your car also came from the factory optimally tuned for drivability under most conditions, since people drive differently and not always change the gear at the right time, also the quality of the fuel can be different at different season and so on.
For sure the cars cannot come from the factory tuned to much for specific climate even at Europe people travel from one end to another and imagine they would have to go to the dealer to tune the car because they travel from Germany to Austria or Sweden for skiing, it would be nonsense.
But you probably know that.
Enjoy your tinkering.

[greygolf8]

Just a quick thought, the MFD has external temp. Would VW go to the effort of using that as part of the MAF ECU calcs for engine / fuel management ?

[Greg Roles]

I sure hope not as it's usually between one and two degrees wrong!

There are various temp and pressure senders that counter for conditions, but the thing I was pointing out is a fuel map, whilst complicated, is still ALWAYS a compromise. I'm kinda keen just to go back to the smoke topic to be honest!

VW want happy customers, I want to annoy v8's.

[Transporter]

I sure hope not as it's usually between one and two degrees wrong!

There are various temp and pressure senders that counter for conditions, but the thing I was pointing out is a fuel map, whilst complicated, is still ALWAYS a compromise. I'm kinda keen just to go back to the smoke topic to be honest!

VW want happy customers, I want to annoy v8's.

I'm sure yo can annoy v8's and even beat them in the rain and around corners.

[jettapilot]

I must say I was NOT impressed when I was smoked this afternoon by some upstart in a black 2.0 Golf TDI!

It's one thing to smoke a petrol guzzling V8, but to smoke a fellow deisel dubbber ....

That's poor form indeed!