A6, AKE: Gas Response/Load Step Issues

Good evening!

It seems like a lot of people are finding their way here from Google, so I'm reaching out to you all!

I have an A6 Allroad with an AKE engine, which is currently causing me some frustration.

"Firstly, it has poor gas response at low RPM (up to approximately 1800 RPM) when cold. From that point onwards, it feels like a switch is flipped, and it suddenly becomes much more responsive."

"I also experience a jerking sensation when shifting loads in the partial load range. It's quite noticeable at 120 km/h in 6th gear; when you slightly release the accelerator, it feels like someone is abruptly cutting off the throttle."

The interesting thing is, once the car is warm, meaning the temperature gauge needle is exactly in the middle, these problems disappear!

That's all about the symptoms.

Now, regarding the "proposed solution" so far:

The camshafts are 40,000 km old, so they can be ruled out. The compression is fully present. Technically, the engine itself is in good condition.

Today, I had the car checked, and as usual, the error memory was empty. By the way, the fuel injector has already been replaced!

According to the Tester (Gutmann) results, the following occurs: I have identified all the parameters that are relevant to me. When comparing the actual and target injection start times, the target injection start time is -15°, meaning before Top Dead Center (TDC), while the actual injection start time is 0.0°?

If you press the accelerator and the car accelerates beyond 2500 RPM, the actual injection start timing suddenly appears, and it's something like -0.3 degrees.

If you slowly release the accelerator, the reading will remain relatively constant until it approaches the idle position, at which point it will return to 0.0°.

Now, if the indicator in the temperature display is in the middle, I have an actual injection start already at idle, which is also at -0.3 at idle.

I also tried adjusting the ESP using the basic settings. I got a reading of 1.2° after TDC (Top Dead Center). The ideal range is 2.0° +/- 2°, which means 0-4° after TDC. So, I'm within the acceptable tolerance range.

Apparently, there's a possibility that my ESP (Electronic Stability Program) is defective, although it seems to be working perfectly, or it could be my engine control unit. That's at least what I was told by the customer service hotline at Gutmann.

Nächste Woche komme ich erst dazu den Wagen an einen V.A.G. Hang the testers.

Has anyone here ever experienced something similar with their car, or could someone possibly help me out? That would be really great! =)

Hi Amando!

Check if you can get access to a laptop (along with someone who's knowledgeable) that has VAG-COM or VCDS installed.

I somehow have a strong feeling that you're using the wrong measurement unit with your "0.0°" or "0.3°" values.

"Nevertheless, I would first log the boost pressure and air mass here - both when the engine is cold and when it's warm."

That would significantly improve the image for debugging .

...otherwise, I can't think of anything else right now, sorry.

Best regards from Munich!

Hey,

Sure, no problem!

So, it should have turbo boost, it can reach 220 km/h (which is typical for an Allroad), and it also has full power once it's warmed up.

"The mass airflow sensor also fits, and I have a second one lying around. Both are working as they should, and there's no change in the vehicle's performance."

Unfortunately, MWB (Mass Wetted Band) data is not available from Gutmann, so I only have the data that can be accessed through the parameters. And that's where it gets strange: the actual and target values for the injection start are very different, or the actual value remains close to zero.

According to the SSP (Service Information Publication), this should originate from the fuel pump control unit, as that's where these functions are regulated, at least according to what I can see in the diagram.

Next week, I will have the complete VAG Tester available. I come from the field, but even as a "learned" person, one eventually reaches the limits of their knowledge .

"müßte" ... "könnte" ... "sollte" ... Ja.

There's a reason I answered you EXACTLY like that - I had something in mind.

Okay, what's important for us now is what the air mass and boost pressure are *in a fault situation* (i.e., when the engine is cold/slightly warm/not at operating temperature).

It's great that your racing bike runs at 220, but... well, that's not your problem, is it? *g*

The Gutmann test isn't bad for general-purpose applications, but it doesn't have any (directly displayed!) weak passwords, of course.
That's also why I'm asking you to find someone who either has the aforementioned software, or you can purchase it here in the shop - just like almost everyone else here (apparently *fg*).

Certainly, the error (e.g., via the fuel temperature sensor) could also be in the ESP or its control unit, but you or we want to FIND the error, not just randomly replace parts. ...at least, that's what I think.

You seem to have a good understanding of technical matters and logic, but we need information about air mass and boost pressure, not how many times you've replaced the mass airflow sensor... *pat on the shoulder*

Okay, go ahead, then we'll see }.

Best regards from Munich!

Hello,

Here's the translation:

"There's some news. Today, we used the VAG 1551 to check the system, and the results for boost pressure and air mass were completely normal. However, in 3rd and 4th gear at full load, the target value of 800 mg/stroke was not being reached, and the actual value was taking a long time to stabilize!"

Last week, I checked the turbocharger's intercooler, and everything seemed tight. I noticed that the actuation lever was slightly stiff in one spot, with a bit of "sticking," but otherwise, the boost pressure seems to be okay.

The start of injection was adjusted using guided troubleshooting with the VAS 5052, but it was only 0.2 degrees too early.

The error persists, even though everything seems to be fine with the car itself. Both the actual and target values can be read correctly using VAG testers!

"However, something else I noticed was a relatively loud 'clattering' sound, likely related to the camshaft speed, specifically on cylinder bank 4-6, which is the driver's side. I suspect it might be a fuel injector that's dripping, but I'm not certain."

Do you have any more ideas?

Are only the camshafts new, or are the hydraulic lifters also new?

Hello,

The camshaft, lifters, rocker arms, and the rocker arm pads on the valves are all new.

I removed and had the 5 injectors inspected, and the result was that one of them was likely defective. A new injector was then installed. The injector with the needle lift actuator is only 2 months old, so only the remaining 5 were inspected.

Nothing has changed as a result of the action. The perceived sluggishness when starting seems to be normal. A smooth transition between 1500 RPM and 2400 RPM doesn't seem to be the engine's strong point, at least that's what others have experienced as well.

In 6th gear, when it's warm, it starts to accelerate noticeably at 70 km/h and actually pulls forward quite well, very smoothly. It doesn't perform as well in the lower gears.

"However, something else I noticed over the weekend, although it was very slight, is that when I gently press the accelerator, there's a slight "jerking" sensation, similar to what you'd feel with a faulty spark plug wire that's not delivering full voltage to the spark plug. Of course, the problem disappears when the engine is fully warmed up, as it should."

Today, I also received information that a valve in the fuel line might be too small. It seems something was replaced at some point, at least in the VW Passat. Is this problem still present in the Audi from the year 2000, or has it already been resolved?

Does anyone perhaps know more about my problem, or has a similar problem been solved here before?

Thank you again for your efforts!

"If the power delivery is so abrupt and inconsistent, something is not right. In the higher gears, it should pull strongly from around 1500 RPM. It could be a number of things: air leak, faulty fuel injection pump, defective mass airflow sensor, worn hydraulic lifters (even though they are new!), or a clogged catalytic converter."

Hello,

The layout is somewhat switchback-like, which fits relatively well, at least in the lower sections, I would describe it that way.

In the higher gears, it really pulls nicely from around 1500 RPM; it's quite capable.

LMM is OK, the air temperature is plausible, and the values are also reasonable. I haven't started working on the catalytic converter yet; I'm still waiting for the RPF (presumably a report or data). The upstream catalytic converter might need to be removed.

ESP is actually a topic where, based on the values I can extract, like fuel temperature and injection timing, it works perfectly fine. What makes me suspicious is that as soon as the needle reaches 90°C, the engine runs perfectly, except for this strange clicking sound, which doesn't seem to have any influence because it occurs on both warm and cold engines and sometimes disappears .

I'm not in the mood to just randomly replace the ESP module. I'll try to have the ESP control unit read out at a Bosch service center on Saturday, but if that doesn't work, I'll put in a different engine; I already have one lined up.

Hello everyone!


Okay, I'm experiencing the exact same problem with the engine stuttering at around 1750 RPM.
"When it's warm, everything seems to be okay. But in my case, a little diesel is leaking from the first cylinder on the left side (when I'm standing in front of the engine). I already tightened the small hollow screw because it was loose. Now, the copper ring underneath might be leaking. I'll probably replace it. But I think the fuel injector is probably defective."
"What's strange is that it runs perfectly normally when it's warm."
Can you replace just one nozzle, or do you have to replace them all?