Lambda Values: Validity and Usage

Hello,

Can someone explain to me when lambda values are acceptable or not?
Speed, gear, thrust, operation, etc.

Vehicle:
Audi A4 2.0 TDI 170hp Engine, Made in Germany, Software Version 9888.

As far as I know, the ideal value for the lambda should be 1.
After restarting the engine, the lambda value is approximately 1.02.
After a certain amount of time (which could be 10 minutes or even just 2 minutes), the value starts to increase continuously.
I created a log about this before:
[/url] https://community.dieselschrauber.org/en/viewtopic.php?p=135505#135505 [url]

If the lambda value after a trip is in the range of 4-5, and I restart the engine, it then returns to a value of around 1.0.

Is this behavior normal?
Is the oxygen sensor defective?

Best regards, Chri[/url].

The lambda value should never be at 1; otherwise, the DPF (Diesel Particulate Filter) will become clogged.

The log looks fine at first glance... (I should also have a MWB 74 log entry here - 170 HP BMR).

Your nozzles aren't clogged yet.

In the 3500-3800 RPM range, when running at full throttle, the L-value must be below 1.4; otherwise, Audi will perform a fuel injector cleaning (during the warranty period). And your engine is still capable of achieving that.

A diesel engine always operates with a lambda value that is "very large," meaning it runs with a significant excess of air.

It hasn't always been like that (so large) with EURO4 TDIs, because the throttle valve somewhat limits their power.
(This is just a very simple, superficial explanation.)

m;

Thank you for the quick response.

Quote:

Your nozzles aren't clogged yet. In the range of 3500-3800 RPM at FULL THROTTLE, the L-value must be below 1.4, otherwise, Audi will perform a nozzle cleaning (during the warm-up period). And your engine can still achieve that.

I had the pleasure of an injector cleaning approximately 2000 km ago.

Let's see how long it takes me to achieve an L-value below 1.4 even when driving at full throttle.
Purely from my subjective perspective, the engine doesn't seem very rev-happy.
Below 2000 RPM, almost nothing happens, but things start to happen between 3500 RPM and 5000 RPM, and then it becomes sluggish.
Is it similar to yours?

Best regards, Chri.

No.

Mine isn't really strong below 2000 (unless it's currently regenerating, then it pulls really hard).
However, if you've already been in the mountains for a while at 1500 meters, something will definitely happen... then the ZMS will start kicking in.

Generally, it's noticeable that it takes some time for the turbocharger to reach the 1.5 bar boost pressure.

"From 2000 onwards, it's pure fun until the end... If I ever get really wild and kick it (which is rare), I always have to watch the tachometer because it spins uncontrollably past 4000 RPM without you noticing where it is. At least, that's how it is when accelerating."

At top speed, which is around 220 km/h, it becomes a bit more sluggish. But I rarely need to go that fast.

m;

Then I probably have a Monday-morning motor .

Do you know which software version is installed on the TCU (Transmission Control Unit)?
I have 9888 on it.
However, there is already talk of models 9970 and 9971.
Do you know if that's correct?

Best regards, Chri.

I have version 1184 installed. It's an update from version 0420, released in August 2007.

Currently, I have one that's at least from 1881, or possibly even newer.

The different versions seem to operate quite differently depending on whether they are installed horizontally or vertically.

I've always heard that the Audi engines, which are the equivalents to the VW engines, are better.

I can confirm this for the 140 hp TDI Passat, and I believe it also applies to the 140 hp TDI A4.

m;

dieselmartin wrote:

Actually, I've always heard that the Audi equivalents to the VW engines are better.

Well, I think the 170 hp piezo direct injection engine is just a "problem engine."

I once posted something about my lambda values before and after cleaning.
/viewtopic.php?p=133567#133567

Regards,
Peter.