A4 TDI AFN Tuning: Questions & Answers

Hi everyone, I'm new to this forum and already have a few questions.

I have an Audi A4, model year 1996, with a 1.9 TDI engine (AFN). The engine has a chip that adds approximately 40 horsepower. Unfortunately, the engine produces a lot of black smoke when accelerating at full throttle. I've read that it might be possible to use larger fuel injectors, which would atomize the diesel more finely, resulting in better combustion and a slight increase in power. Additionally, this should reduce the amount of black smoke. Is this true? Where can I find such fuel injectors?

Two weeks ago, I had an accident that damaged the central locking and control unit (LKK). My question is whether it would be possible to install a larger LKK in my Audi, and if so, would it be beneficial?

These are probably questions that have been asked many times before. I am very grateful for your help, though.

Best regards from Berlin, K.R.

a4ever0815 wrote:

The engine has a chip that adds approximately 40 horsepower. Unfortunately, the engine makes a lot of noise when running at full throttle. I have read that it might be possible to use larger fuel injectors, which would atomize the diesel fuel more finely, resulting in better combustion and also a slight increase in power.

Hi.

Well, that's quite a story... In my opinion, larger nozzles tend to produce a worse atomization .

But the experts in pumps and nozzles should be able to provide more information on that.

Quote:

Furthermore, this is supposed to reduce Russian interference. Is that true??? Where can you get those fuel injectors?

Basically, you can find replacement nozzles everywhere, you just need to know which "incorrect" nozzles you want for your car.

As far as I know, the only effective way to combat carbon buildup (in an otherwise healthy engine!) is to increase the turbocharger boost pressure.
So, either have the chip reprogrammed (and risk the (standard) turbocharger with the AFN engine at 150 hp ), or increase the boost pressure yourself --> 10c tuning (although the turbocharger could also fail, but then you have it under your own control ).

P.S.: Could you please reduce the size of your avatar? Here, it's mainly about factual information and less about images .

I read about the nozzles at the VW workshop where the KW powerbox was tested. I can't say whether the report is a fairy tale .

'Isn't it true that increasing the boost pressure will cause more smoke?' My tuner suggested that reducing the boost pressure might improve things. However, wouldn't that also mean less power?'

What do you mean by increasing the boost pressure yourself? How is that supposed to be done?

Excessive soot formation occurs because there is insufficient oxygen available for the amount of diesel injected. A reduction in boost pressure (even less O2) will, in my opinion, only increase this effect.
'I'm speaking from experience, as my engine was producing a lot of smoke under full load with a boost pressure of 0.9 bar, especially with the tuning activated. By replacing a resistor in the engine control unit, I was able to increase the boost pressure to 1.1 bar, which significantly reduced the amount of smoke.'
By the way, take a look at this: http://www.dieselschrauber.de/10cent.html It describes the measures for increasing boost pressure. However, everything is at your own risk, and I strongly recommend having an LDA in this context.

Well, I think this whole thing is quite risky. I'm an energy electronics technician and I work with similar things, but I'm not really keen on soldering around the control unit.
I'm going to ask my tuner if he can increase the boost pressure.

How about the intercooler? Does anyone have any experience with it?

a4ever0815 wrote:

Isn't it true that increasing the boost pressure results in more smoke??? My tuner suggested that reducing the boost pressure might improve things. However, wouldn't that also mean less power?? What do you mean by increasing the boost pressure yourself?

How is that supposed to be done?

Hi.

Whoever talks such nonsense and calls themselves a "Tuner" should have seen me twice: for the first and last time .

zzZZ has already explained the issue with the price increase.

Very good link regarding the topic of LLK (likely referring to 'Landespflegekräfte' or a similar term).

http://www.passat3b.de/forum/daten/Forum6/HTML/000455.html

Ansonsten nimm einen S4 oder RS4- LLK und baue die S4 Radhausschale ein. It costs money!

Regards,

Manuel.

a4ever0815 wrote:

Well, I think the action is quite risky. I'm an energy electronics technician and I deal with such things, but I don't really want to solder anything around the control unit. I'm going to ask the tuner if he can increase the boost pressure...

Hi.

He'll probably advise you to reduce the boost pressure - perhaps because he secretly knows that his chip is already pushing the poor AFN turbocharger into the "red zone" .

However, it would still make sense if those extra 40 horsepower were real: Reduce the turbo boost and lower the fuel injection amount to the point where it produces significantly less soot.
It probably costs at least 10 horsepower, but it's not so hard on the engine anymore .

As I said, I will inquire with him. And if he doesn't do it, I will install a boost gauge myself and try the resistor trick.
What should the maximum boost pressure be for an AFN engine? Should it be 1.1 bar, as zzzZZ mentioned (with a new resistor)?

Thank you very much for the link. It's very informative.
The only question is whether the S4 intercooler or the RS4 intercooler will fit on an A4 TDI without any major issues.

You need the linkage and the linkage bracket. The mounting points are the same.
You may need to use a silicone hose.

My Audi's engine is chipped and running at a maximum boost pressure of 1.1 bar, with occasional overboosts reaching up to 1.5 bar.

Regards,

Manuel.

a4ever0815 wrote:

As I said, I will inquire with him. And if he doesn't do it, I will install a boost gauge myself and try the thing with the resistor. What should the maximum boost pressure be for the AFN engine?? Is it as zzzZZ wrote (with a new resistor, 1.1 bar)?

Hi.

Over the long term, the serial charger (at higher RPMs) should probably not exceed 1.2 bar.

"I think your tuner has probably already explored this to its fullest extent. Therefore, the only remaining solution that doesn't involve further damage to the components is likely to reduce the fuel injection amount until the soot becomes acceptable, which will result in a loss of power."

Or, if you want to maintain the current performance without producing more soot, you can install a larger turbocharger and run it at a higher pressure. In that case, a larger intercooler would also be very beneficial.
However, you would experience a significant turbo lag: The turbocharger builds up pressure later, and the larger intercooler must be filled with pressure before the compressed air reaches the engine.
Some people, you know, are into a correspondingly powerful and noticeable "boom."

I'll be able to tell if the turbocharger is being fully utilized by reading the boost pressure gauge. If the maximum value is significantly lower than expected, can the resistor be adjusted accordingly?

I've been thinking about changing the turbo. Which one would be suitable for me: the VNT-17 or the VNT-20?

Thank you very much for your help.

a4ever0815 wrote:

I will be able to tell if the charger is being fully utilized by reading the boost pressure indicator. If the maximum value is significantly lower, can the resistor be adjusted accordingly?

Okay.

Quote:

I've already been thinking about changing the turbo. Which one would be suitable for me? The VNT-17 or the VNT-20?

Unfortunately, I don't know the specifications of the individual chargers. However, if the "17" model can handle approximately 20% more mass at a correspondingly higher pressure compared to the "15" model, it should probably be sufficient.

@Manuel Thomas: Hast du den LLK bei dir verbaut??? In an Audi A4?

I would be very grateful if you could provide the part numbers!
My Audi is currently still in the workshop, and I actually don't want them to install the original coolant.

I need the part number for the Garrett VNT-17 turbocharger.
Thank you very much.

I didn't install the liquid cooling system because it's far too expensive for me. It's made entirely of aluminum, which is why it costs so much.

I often check eBay to see if there are any cheap and useful items available.

Regards,

Manuel.