Audi A6 TDI: Adjusting Fuel Injection Timing

Hello everyone,

A few months ago, I bought an Audi A6 Avant TDI with a 132 kW engine and a Tiptronic transmission. It's a great car, and it has good acceleration.

Now it's becoming clear that the car enjoys a drink: city driving consumes around 13-13.5 liters, highway driving about 10-11 liters, and country roads around 8-9 liters.

In my opinion, that's too much fuel consumption even for an automatic transmission. Two colleagues who drive a BMW 530d say they get around 8-9 liters per 100 kilometers on the highway.

My AKE now has 140,000 km on the odometer. The timing belt was replaced at 120,000 km (by the previous owner). I haven't been able to reach its top speed yet; I always brake around 230 km/h (--> winter tires!!).
However, it tends to smoke quite a bit from the back, even when it's already hot.

VAG-COM says: No errors... All values in measurement block 0 are within the normal range.
However, in the MWB 4 software, I can read values for 'injection timing' ranging from -1.6° (idle) to 0° (4000 RPM). --> A value of -1.6° seems unusual to me.

Is it possible that the injection timing is misadjusted?
Can I correct this using software?

Can I log in to the control unit? If so, how? (12233 doesn't work).



Greetings / Larry

I'm starting to get the impression that all Audi and VW cars with Tiptronic transmissions consume a lot of fuel, and that this level of consumption is considered normal.

I'm experiencing the same problem with the AFB Tiptronic.

Regarding the 530D, I can confidently say that 8-9 liters is far too much [fuel consumption].
We have a car with 198 horsepower in the company. It has a top speed of 170-190 km/h on the highway and consumes 7.2 to 7.5 liters per 100 kilometers. It accelerates smoothly and can sometimes reach speeds exceeding 200 km/h.

We can probably only dream of achieving those values.

Okay, let's get real. Does anyone have a 2.5 TDI Tiptronic that averages under 8 liters per 100 kilometers and manages to achieve the manufacturer's stated average of 6.1 liters on country roads with normal driving? It would be interesting to see if the automatic transmission really consumes that much fuel.

Best regards, Manuel.

Hello,

http://www.dieselschrauber.de/Solldaten_6_Zylinder_VE.html

If the fuel consumption is too high, a faulty or clogged catalytic converter or exhaust system could also be the cause.

Best regards, Rainer.

Hmm... a clogged exhaust or catalytic converter... wouldn't that also cause a decrease in top speed, and possibly be visible in the boost pressure?
A blocked exhaust system means reduced exhaust flow, which leads to poorer cylinder filling and less power. Furthermore, it would likely result in higher residual pressure in the cylinder that the turbocharger has to overcome. The turbocharger also wouldn't reach its full potential because it lacks sufficient exhaust volume.


I don't think those are my symptoms.

I can accept a generally high fuel consumption for this type of vehicle, but 13 liters per 100 kilometers in the city is a bit too excessive. And 11 liters per 100 kilometers on the highway is also quite high.

I know that these kinds of errors (which might not even be errors) are difficult to detect... but I'm a little ambitious here.

Can you help me with logins or something similar?

I had already downloaded the table with the target data; it was helpful.

Thank you. Larry.

Hi Larry,

Polarlarry wrote:

Hmm....a clogged exhaust or catalytic converter...wouldn't that also cause a decrease in top speed...or even be visible in the boost pressure? A blocked exhaust system means reduced exhaust flow, which leads to poorer cylinder filling and less power. Furthermore, it would likely result in higher residual pressure in the cylinder that the turbocharger has to overcome. The turbocharger also wouldn't reach its full potential because it lacks sufficient exhaust volume. I don't think those are my symptoms. I can accept a generally high fuel consumption for this type of vehicle, but 13 liters per 100 kilometers in the city is a bit too excessive. And 11 liters per 100 kilometers on the highway is also quite high. I know that these kinds of errors (which might not even be errors) are difficult to detect... but I'm a little ambitious here. Can you help me with logins or something similar? I had already downloaded the table with the target data; it was helpful. Danke. Larry

You are absolutely right about the symptoms, but it also depends on how severely something is clogged. And would you notice a top speed that's less than 5 km/h? In any case, there would be a slight increase in fuel consumption, even if the car still drives almost normally.

I'm not really sure where to start looking when it comes to your 140mm [item/size].
I once had an A6 Avant TDI with 132kW and automatic transmission (I have no idea if it was a Multitronic or Tiptronic). The entire time, I had a trailer attached, and in a roughly one-third mix of city/country road/highway driving, I definitely used less than 10 liters per 100km. And I wasn't even particularly gentle with the accelerator; after all, I wanted to see how 180 horsepower felt .
Could it be that when replacing the timing belt on a V6 TDI engine, some mechanics might also loosen the camshaft sprockets from the camshafts, following instructions or their own judgment, to make it easier to install the new timing belt?
A slightly twisted camshaft would explain the increased fuel consumption and low air mass readings (assuming the air mass meter isn't already performing poorly).

Best regards, Rainer.

Well, even so, I wouldn't generally praise the 530d *too* highly...
A colleague had the sedan, and an acquaintance had the station wagon.
Both of them have moved on now.
One person was driving a Mercedes E 320 CDI, while the other was driving a gasoline-powered BMW.

Both vehicles had issues with the turbocharger, and additionally, the station wagon had leaking injectors and a corroded high-pressure pump.

'Your 2.5 is also a Quattro – you might want to mention that, because that probably adds at least another liter [of fuel consumption]... So, I don't think your figures are that bad.'

Regards,
arne

Hello everyone,
However, it tends to smoke quite a bit from the back, even when it's already hot.


Hello,

Have the injectors been inspected for their spray pattern and any signs of dripping? At the current temperatures, a whitish smoke (e.g., water vapor) is not unusual. However, it could also be unburned diesel fuel that is producing the white smoke. Furthermore (and this should apply to both AFB/AKN and AKE engines), check the O-rings on the injectors to see if any diesel fuel is leaking out.

Okay, so let me summarize:

'There might be a restriction in the exhaust system that is reducing my top speed by a little bit (5 km/h) and causing higher fuel consumption.'
2. Nozzles may have leaking O-rings (--> I like this tip).
3. I DO NOT have a Quattro.
4. Slightly twisted camshaft after timing belt replacement... (I like this one the best).


Okay, so my question is: how can I determine the correct position of the camshaft, or how much it's rotated?
Does anyone have any helpful information on this?

'Furthermore, I'm still surprised that there apparently aren't any codes available for my engine control unit... is it perhaps too new?'

Hello,

To check the camshafts, you first need to screw the vacuum pump onto the left cylinder. On the right cylinder, you need to remove the cap on the front side. Now, turn the engine using the crankshaft (it will be difficult to move it; with a manual transmission, you can also engage a gear) until you can see through the oil filler opening that the camshaft is at Top Dead Center (TDC). Above the oil pan of the middle cylinder, there is a closing plug (like a side panel); a pin should now fit in there (turn the shaft until it fits exactly). Now you should be able to insert the two camshaft alignment tools (40mm wide by 5mm high) precisely into the notches on the camshafts. If they don't fit, the camshaft settings are incorrect.

I'm experiencing diesel fuel leaking from the injector nozzle. What potential damage could this cause to the engine?

Best regards,
Manuel

Hi Polarlarry,

Sorry, I thought all models with 180 horsepower also had all-wheel drive. It seems that was only the case for the older models.

Regards,
arne

Hello Larry,

There is no login required for this function.

If you have the full version of VAG COM, then it's accessed through the basic settings menu, display group 4.

If you select this mode with a warm engine (above 85°C), the control unit will alternately trigger the ignition at its earliest and latest possible points during idle. You can recognize this by loud knocking noises.

For early blooming varieties, you should aim for a reading between 14-17° v.OT (vegetative open time), and for late blooming varieties, 4-0 n.OT (negative vegetative open time) is ideal (2 being the target).

If you're working outside, the belt tension needs to be checked, or the right camshaft pulley needs to be adjusted. That's what my repair manual says.

I can send you something via email if needed.

Good luck!

Rainer.

Okay, I'll check the values now... but based on what Datsun is saying, the injection timing probably isn't that far off.

However, it would be a shame. It's always nice to find an error and then fix it.

First of all, thank you to everyone... I think I can now do enough searching and testing for the time being.

Hey everyone,

I finally found the time to test my AKE engine.
I also received the login for the MSG system for the AKE.

So:

MWB4: The injection molding process is within the acceptable range of -3.8 to 15.2°.
However, he's just about to inject it, and he's injecting it quite late.
I can imagine that it might consume a bit more in that situation.
He could also play better...

If I wanted to adjust the timing belt now, do I really have to disassemble half of the front of the car (remove the bumper, viscous fan, etc.)?

The friendly person said that it's not possible for less than 300 Euros...

My question is: Is it worth investing in early ignition technology? Or does it offer so little benefit that I should just forget about it?

Thank you for your answers.

Polarlarry wrote:

... MWB4: The injection molding process is within the acceptable range of -3.8 to 15.2°. ... My question now is: Is it worth considering a setup that promotes early ignition?

It's unlikely, but it can't hurt to try.

Thank you for the answer, Rainer.

If it really doesn't make much of a difference... then why do so many people ask about adjusting the ignition timing by 1-2 degrees?
(According to proponents of the early ignition theory), this is supposed to generate steam.

I have to admit, I'm not entirely satisfied with the answer yet (which is probably because I'm a curious physicist).