00561 and low boost

[UrS4boy]

...I wonder if the limit not reached is basically indicating a lean mixture which the lambda cannot control....

Lean? Who said anything about lean?

2413 (Blink Fault Code), 00561 VAG1551/2 Fault Code Number
Mixture Adjustment,
Adaptation limit exceeded, Adaptation limit not reached, Leakage in exhaust system before 3 Way catalytic converters, Incorrect signal for Mass Air Flow Sensor, Spark plugs, ignition coil(s), or Ignition Coil Power output stage malfunctioning
Symptom: Rich mixture, increased fuel consumption

[prj]

Lean? Who said anything about lean?

2413 (Blink Fault Code), 00561 VAG1551/2 Fault Code Number
Mixture Adjustment,
Adaptation limit exceeded, Adaptation limit not reached, Leakage in exhaust system before 3 Way catalytic converters, Incorrect signal for Mass Air Flow Sensor, Spark plugs, ignition coil(s), or Ignition Coil Power output stage malfunctioning
Symptom: Rich mixture, increased fuel consumption

Where are you getting this information from?
00561 is an umbrella fault code, it is pretty much worthless without further information.
00561 just means that O2 feedback needs to adjust more than a certain amount to get the mixture back in check. This is a long term error code, meaning the long term fuel trim starts to get above or below a certain value.
It is similar to the 00537 error, which is exactly the same, except for the short term fuel trim.

The short term and long term fuel trims can be observed in group 000 in VAG-COM - value 9 and 10.
They are both multiplicative, and are multipliers for the injection time.
To be exact, injection time is multiplied by X/128. So if it is 128, there is no adjustment, less than 128 means you are running too rich and it is pulling fuel, and more than 128 means you are running too lean and it is adding fuel.

You can get the following variations:
Adaptation limit (ADD) exceeded
Adaptation limit (ADD) not reached
Adaptation limit (MUL) exceeded
Adaptation limit (MUL) not reached

Exceeded means you are running too lean, and it is adding too much fuel via O2 feedback.
Not reached means you are running too rich, and it is pulling too much fuel via O2 feedback.

Without the second part of the fault code or a Group 000 log it is impossible to tell what the problem is...
P.S. Feel free to incorporate this information somewhere, if you like. I am 100% sure of everything I wrote in this post.

[twoqu]

Well if you look at page 33 of the Motronic manual there are 4 possible versions of the 00561 code, two for exceeded and two for not reached. It seems to me that the exceeded are related to a rich condition and the not reached relate to a lean condition. Its just that they have listed the possible faults as rich related conditions.
I know factory documentation is not infalible but it sort of makes sense. For example how can a fuel pressure related problem (too high/low) both cause the same symptoms. As I read it they indicate an exhaust leak as a possible cause for the not reached condition. Is that not consistant? Does a leaking or less restrictive exhaust not lead to a weaker mixture, everything else being equal. Of course the Motronic attempts to correct these issues but where it cannot it throws the relevant code.
Thats why I was posing the question. Whats the difference between limit not reached and limit exceeded.

[twoqu]

Thanks Dmitri!
Looks like I got it the wrong way round thanks to the confusing factory info!
We need to rewrite some of this stuff to reflect experience.

[UrS4boy]

Where are you getting this information from?

Here: http://www.sjmautotechnik.com/troubl...g/20vcodes.htm

It has been our experience over here with *just* AANs to sort out, that when the 2413 blink code (VAG 1551 = 00561) is pulled, it is invariably a boost leak that simultaneously results in low boost and rich running conditions.

Your experience could be different.

[prj]

Here: http://www.sjmautotechnik.com/troubl...g/20vcodes.htm

It has been our experience over here with *just* AANs to sort out, that when the 2413 blink code (VAG 1551 = 00561) is pulled, it is invariably a boost leak that simultaneously results in low boost and rich running conditions.

Your experience could be different.

As I said, 00561 can be too rich or too lean. The code alone does not indicate this.
The extra information on the second line, is what will tell you.

Usually when there is a boost leak, it gives an "exceeded" error, because unmetered air is drawn in post-throttlebody on low load and mixture goes lean.
Lambda control is not capable of diagnosing what happens on boost, because the ECU goes open loop.

[UrS4boy]

...Usually when there is a boost leak, it gives an "exceeded" error, because unmetered air is drawn in post-throttlebody on low load and mixture goes lean....

That does not make any sense. How does air get drawn in "post" (as in after) the throttlebody??

What makes sense is the MAF meters a flow of air and the signal goes to the ECU. The ECU checks the throttle position, the RPM, boost levels, etc, and looks up what the required duty cycle for the injectors should be for that flow of air. However, with the boost leak, a portion of the air that was metered by the MAF does not show up at the throttlebody. The ECU doesn't react fast enough and the amount of fuel added to that smaller mass of air is the same as it was selected for the larger mass of air. The result is a rich mixture.

[Dan]

However, with the boost leak, a portion of the air that was metered by the MAF does not show up at the throttlebody.

Correct me if I'm wrong, but:

That makes sense so long as the relative pressure between the turbo and the throttle body is positive. Air that was metered by the MAF will leak out and therefore, as you say, a portion of the metered air will not arrive.

If, however, the relative pressure is negative -- that is, whenever the turbo is not providing boost but instead is a restriction on the flow of air -- then the engine could draw in air from the atmosphere rather than through the turbo and MAF. Therefore you would have more air than was metered.

Does that make sense? or have I got the wrong end of the stick, too?

[UrS4boy]

Dan: Under vacuum, i.e. off boost, throttle body closed or only partially opened, yes, it would be possible to draw unmetered air in through a hose some connected to the throttle body. However, in our UrS AAN experience, the hoses most likely to split under boost are the Michelin Man hose beteen the cross-over tube and the OE SMIC. Under vacuum, this hose most often closes up and does not let air in under vacuum. This makes it difficult to diagnose without a thorough boost leak test and physical inspection of the hose (while under test).

The one UrS AAN hose that could fit your vacuum scenario is the MAF to turbo hose. These are getting old and soft and are starting to split. That split would allow unmetered air into the system.

(Waits for prj to jump on this last statement).

[prj]

That does not make any sense. How does air get drawn in "post" (as in after) the throttle body??

OK, back to basics.
Very simple, because there is a split in a hose that goes directly to the inlet manifold and bypasses the throttle body.

What makes sense is the MAF meters a flow of air and the signal goes to the ECU. The ECU checks the throttle position, the RPM, boost levels, etc, and looks up what the required duty cycle for the injectors should be for that flow of air. However, with the boost leak, a portion of the air that was metered by the MAF does not show up at the throttlebody. The ECU doesn't react fast enough and the amount of fuel added to that smaller mass of air is the same as it was selected for the larger mass of air. The result is a rich mixture.

Incorrect.
First of all, IPW = MAF/RPM*Enrichment

If you have a leak in any of the hoses attached to the inlet manifold, or the breather, then it will suck in air through there, instead of sucking it through the filter and the MAF.

Result will be that the MAF provides a lower signal and IPW goes down. Less IPW = less fuel = lean.

The moment you reach positive pressure in the manifold, metered air will start escaping and the mixture will go rich, because more air is metered by the MAF than goes into the engine.
The exception to this are holes in the breather or between MAF and turbo, because the check valve beneath the manifold will close, and the mixture will remain lean, as air is drawn in through the holes in the breather instead of going through the airbox.

The only case where there would be no lean condition is if the leak was between turbo and throttle body.
There is never vacuum there, but there is no pressure either until the throttle is open, because the dump valve is open.

[UrS4boy]

For the less informed than you, you need define your terms so we can follow along:

As in IPW = ??? I know IPA (India Pale Ale) but not IPW What are the units of "IPW"?

MAF = a voltage from the Mass Air Flow sensor or flow in m^3/sec?
RPM = okay, got that.
Enrichment = What? A/F ratio? What?

Do you have reference for the definition of IPW that we could check for ourselves?

I will concede that there could be a leakage of air from the PVC system into the intake *AFTER* the throttle body BUT that would ONLY occur if there is a vacuum (less than atmospheric pressure) condition in the intake manifold and one of the components of the PVC system as failed. We agree that under boost, the PVC one-way bleeder valve *should* close the PCV system off from greater than atmospheric pressure in the intake manifold. REF: http://forums.quattroworld.com/s4s6/msgs/22506.phtml

End of the day, do you really think the OP's problem is the PCV system? I don't think so. I think you think it is a boost hose or at least a hose between the MAF and the throttle body? I certainly do.

And oh yeah, Peace on Earth, Goodwill to Mankind.

Seriously. We need it.

[prj]

For the less informed than you, you need define your terms so we can follow along:

As in IPW = ??? I know IPA (India Pale Ale) but not IPW What are the units of "IPW"?

MAF = a voltage from the Mass Air Flow sensor or flow in m^3/sec?
RPM = okay, got that.
Enrichment = What? A/F ratio? What?

Do you have reference for the definition of IPW that we could check for ourselves?

I will concede that there could be a leakage of air from the PVC system into the intake *AFTER* the throttle body BUT that would ONLY occur if there is a vacuum (less than atmospheric pressure) condition in the intake manifold and one of the components of the PVC system as failed. We agree that under boost, the PVC one-way bleeder valve *should* close the PCV system off from greater than atmospheric pressure in the intake manifold. REF: http://forums.quattroworld.com/s4s6/msgs/22506.phtml

End of the day, do you really think the OP's problem is the PCV system? I don't think so. I think you think it is a boost hose or at least a hose between the MAF and the throttle body? I certainly do.

And oh yeah, Peace on Earth, Goodwill to Mankind.

Seriously. We need it.

When the manifold is out of vacuum lambda control is inactive, so a fault can not be diagnosed.
If this fault code is present and it is "exceeded" then assuming nothing is wrong with the map, it means there is a leak in one of the hoses connected directly to the manifold.

IPW is injector pulsewidth. Enrichment is ECU's internally calculated multiplier, made up of all the fuel maps + the lambda fuel trim.

[twoqu]

So is this code only related to idle (vac) and transient vac/atmospheric conditions? I think people get worried as they think the Lambda controls the fueling throughout the range. So a faulty Lambda sounds like a disaster.
As the OP has the not reached problem might this be related to a fuel pressure issue such as using a 4bar rather than a 3.8bar fpr. Although it does not explain why the 00561 only appeared after the downpipe/exhaust was changed unless there has been some subtle change in the Lambda position that has effected something.
If the hoses are ok then might it be something like the injector inserts. If its leak free, then possibly the MAF.

[twoqu]

Note on fault code 00561:

◆ add = additive - The fault has less effect as engine speed increases.
◆ mul = multiplicative - The fault has more effect as the engine speed increases

[prj]

So is this code only related to idle (vac) and transient vac/atmospheric conditions? I think people get worried as they think the Lambda controls the fueling throughout the range. So a faulty Lambda sounds like a disaster.
As the OP has the not reached problem might this be related to a fuel pressure issue such as using a 4bar rather than a 3.8bar fpr. Although it does not explain why the 00561 only appeared after the downpipe/exhaust was changed unless there has been some subtle change in the Lambda position that has effected something.
If the hoses are ok then might it be something like the injector inserts. If its leak free, then possibly the MAF.

In this ECU the fuel trims do not affect WOT operation... When it goes open loop, all it reads are MAF and RPM for fueling and ignition.
If the MAF is defect and an error condition is present, then the throttle plate angle is used instead of the MAF signal.