A3 TDI: High Fuel Consumption - What to Do?

Hello!
What could be the cause of a sudden, drastic increase in fuel consumption in a 1996 Audi A3 1.9 TDI with 110 hp (AFN, AHF, or similar)? Until recently, it was consuming 5.5 - 6.3 liters per tank, but now it's suddenly using 8 liters per 100 km, even with the same driving style and routes.
Otherwise, it seems like nothing has changed! It accelerates normally, doesn't jerk, doesn't lose fuel, etc. The car belongs to my brother, and we initially replaced the MAF sensor. It was still the original one and completely black. He says that, based on his feeling, there hasn't been much of a change in performance (maybe it pulls a little better at full throttle). Of course, we can't say anything about fuel consumption yet. You have to wait for a full tank, since it doesn't have a MFA . Let's see. But what else could it be if it's NOT the MAF sensor?

'Whatever he already has is this terribly long 'grinding' sound from the starter motor when starting, but only when the engine is warm. It's really not normal how long he has to 'hold' the key before the engine finally starts. It's definitely 5 seconds every time. But he's always done that, and it's not related to fuel consumption, although it's very annoying. However, the starter motor seems to spin fast enough, unlike the starter motor in my sister's Beetle. That one doesn't reach its full speed until it's warm. Maybe it's this valve in the fuel injection pump (it wasn't the cause of the 'grinding' in the Beetle, and we're still looking for the reason there, but it's probably the starter motor?). The fuel delivery should be correct since the timing belt was replaced.

Thank you for your expert assistance.

Greetings.

What about the fault memory and the vehicle diagnostic system? The mass airflow sensor can be checked definitively, maybe it was all for nothing. Do you have any air bubbles in the line?

96kwtdi wrote:

Hello! What could be the cause of a sudden, drastic increase in fuel consumption in a 1996 Audi A3 1.9 TDI with 110 hp (AFN, AHF, or similar)? Until now, it has been running on a tank of fuel with a consumption of 5.5 - 6.3 liters. Suddenly, it's using 8 liters per 100 km! Otherwise, it seems like nothing has changed! It accelerates normally, doesn't jerk, doesn't lose fuel, etc. . . . But what else could it be if it's NOT the MAF sensor?

For example, a stuck fuel injector, a clogged air filter, a stuck AGR valve, a stuck VTG (variable turbo geometry), or a vacuum leak.

Quote:

The start date for the funding should be appropriate, as the ZR (Zahnriemen - timing belt) was already replaced.}
Unacceptable amount of substandard material being supplied for TDIs!

Hello!
A loan-to-market ratio of EUR 90,- and after 110,000 km is never wrong, especially since it was still the original one.

But Ulf, aren't your assumptions always associated with a loss of performance?
It's definitely not a simple lumbar puncture. A myelogram will likely be performed if the lumbar puncture doesn't provide enough information.

Does anyone have any tips for dealing with a starter motor that 'grinds' or struggles to engage when the engine is warm?

Greetings.

96kwtdi wrote:

A loan-to-market ratio of EUR 90,- and after 110,000 km is never wrong, especially since it was still the original.

118,000 km with a K&N air filter... still the first one...

Quote:

But Ulf, aren't your assumptions always associated with a loss of performance?

Not necessarily. Ulf is right: There are some very strange issues with the TDI engines.

96kwtdi wrote:

... Does anyone have any tips for dealing with a starter motor that "grinds" or struggles to engage when the engine is warm? ...

Search function!

/viewtopic.php?t=11189&highlight=warmstartproblems
(Please read until the end!)

So, a K&N filter has never been installed and will never be installed, and a performance chip has also never been installed.

Thank you for the link, but I don't think the starter motor is the problem.

Greetings.

96kwtdi wrote:

Quote: The start date for the funding should be appropriate, as the ZR (Zahnriemen - timing belt) was already replaced. Unjustified conclusion, given the amount of garbage that is being delivered to TDIs!

Timing belt replacement on my V6 engine, performed with markings and without using rulers (at a certified workshop ).

96kwtdi wrote:

... not even a chip was ever installed.

I haven't said anything about a chip...

Quote:

Thank you for the link, but I don't think the starter motor is the problem.

So, not finished reading it yet...

Hello!

Herr Antje wrote:

Timing belt replacement on my V6 engine, performed with markings and without using rulers (at a certified workshop

).

I only use markings when working on VP motors. It's much faster that way.
It is considerably more reliable because no "critical" screws need to be loosened. This is, of course, assuming the necessary skill and care are applied.
In 9 out of 10 cases, the dynamic injection start does not need to be adjusted.
EDIT: The pulley wheels are NOT to be loosened!

I've seen a lot in my time, but having to remove the camshaft gear for a timing belt change is more of a testament to the developer's lack of foresight. Inexperienced or careless mechanics regularly cause consequential damage here. Using old screws, dirt in the cone, not paying attention to the torque, twisting the camshaft...
Here in this forum, performance issues that occur *after* a timing belt replacement are regularly reported.

BYE
TDI mechanics.

... also, a chip was never installed either.

I haven't said anything about a chip...

Thank you for the link, but I don't think the starter motor is the problem.


So, not finished reading yet...

Hi Bertil!
Actually, yes. Why? Has anything else happened recently?

Greetings.

tdi-schrauber wrote:

I only use markings when working on VP motors. It's much faster that way. It is considerably more reliable because no "critical" screws need to be loosened. This is, of course, assuming the necessary skill and care are applied. In 9 out of 10 cases, the dynamic injection start does not need to be adjusted.

If you mean that I have a different opinion. Are all timing belts exactly the same length? Also, the camshaft pulleys were removed, and there were markings on them (V6) . The reason for this, with the V6 engines, is usually that they are concerned that the two points will not be 100% sealed afterwards.

tdi-schrauber wrote:

I've seen a lot in my time, but having to remove the camshaft gear for a timing belt change is more a sign of poor design from the developers. Inexperienced or careless mechanics regularly cause consequential damage here. Using old screws, dirt in the cone, not paying attention to the torque, twisting the camshaft... Here in this forum, performance issues that occur *after* a timing belt replacement are regularly reported.

"My timing was really off. You mentioned that the camshaft sprockets need to be removed. It's probably more accurate to mark them with a paint pen than to use rulers, right? Also, with the V6 engine, it's often reported that the timing isn't 100% correct after being changed because people have used paint pens to mark things. This can then cause knocking or a loss of power."

Save time, ignore the repair manual, and still charge full price – my respect.

Hello!

Ich löse keine Riemenräder beim ZR-Wechsel an den 4-Zyl. VP-Engines!
That probably wasn't clear.

And yes, the belts are the same length within the tolerance of the tooth width. Otherwise, there would be serious problems!

Hello, it's me again!

'Has anyone reached a logical conclusion yet regarding the 'organ problem' and the temporary removal of the G62? I mean, those makeshift solutions with different resistors can't be the right answer. Does anyone know a proper fix?'

Thank you.

Greetings.

96kwtdi wrote:

... "Has anyone reached a logical conclusion regarding the 'organ problem' and the temporary removal of the G62 component? I mean, those makeshift solutions with different resistors can't be the right approach. Does anyone know a proper solution?" ...

Still haven't read the thread?

Here are some of the most important comments from various people:

Quote:

... Okay, let me summarize: A new engine has full compression, the starter and battery provide full speed, so the compression heat is sufficient to ignite even a small amount of fuel. In older engines, all of this gradually deteriorates, and it takes a few more revolutions for them to start. When it's cold, this isn't a problem because the amount of fuel needed to start is higher. Because the (warm) fuel quantity required for starting has been continuously reduced in the interest of emission regulations, this effect is naturally more pronounced in newer models. ... Keep in mind that the VP37 is always subject to wear and tear, and even the smallest deviations can cause problems (e.g., reduced pressure, less accurate timing). If you then add a starter motor that rotates slightly slower, and the compression is a bit weaker, the combination of all these factors can lead to these problems. ... It seems you still haven't understood that the VP37 (as well as the nozzles) is a wear part. Depending on the treatment and external factors, the components can be far outside their nominal tolerance, for example, due to inadequate maintenance or unsuitable fuel. Emission regulations specify a maximum emission limit during startup. Therefore, the engine is controlled accordingly during startup. For a warm start, this means a reduced fuel quantity and a "mid-range" injection timing. This is perfectly sufficient with correctly functioning injection equipment and a correct starter motor speed. If the engine speed drops below the minimum (e.g., 300 RPM) or the fuel pump is delivering insufficient fuel, it is no longer sufficient. ... To have even a minimal degree of control over the start of injection (which is only regulated once the engine is running!), the pump speed must be at least 150 RPM (wearing part: starter motor). Furthermore, the impeller pump must be functioning correctly, there must be no air in the system, and the throttling valve or pressure regulating valve (depending on the application) must also be in good working order. To ensure accurate metering, the pressure inside the pump housing must have a minimum value. In addition, the control valves and distributor shaft must be within their specified tolerances. Of course, the pressure relief valves (or throttles, depending on the application) and the injection nozzles must also be in good working order. ...

I consider the last section to be particularly important.


The solution to that is probably well-known -> orgiastic partner swapping .

96kwtdi wrote:

Hello, it's me again! "Has anyone reached a logical conclusion regarding the 'organ problem' and the temporary removal of the G62 component? I mean, those makeshift solutions with different resistors can't be the right approach. Does anyone know a proper solution?" Thank you. Greetings

Another "DIY solution":

- Set the start of the spraying process to occur earlier.
- Increase the initial amount.

It's not a problem to change it via a chip modification, but I haven't had any cars with a "start problem" yet.
"However, it works perfectly well with plant-based TDIs. It only won't restart the engine if the starter motor is faulty or something like that."

Best regards, Rainer.

Hello everyone!
So, it's the starter motor after all, even though it sounds like it's spinning at a normal speed?

What do you mean by 'sex marathon'? I don't quite understand.


Thank you all!
Greetings.