Emissions Test: TDI Engine Stress Test?

Hello everyone.
I've been following this forum for about a year now, and I'd like to...
Thank you for the many pieces of information I have already been able to find here.

I drive a New Beetle 1.9 TDI / ALH.

Regarding my question:
Does anyone know about the exhaust emission testing procedure?

My 'master' startled me with the statement:
'We'll give it full throttle a few times, right up to the limit.'

Is this procedure correct?
It definitely won't do the engine any good (grumble!).

Thank you in advance for your answers.
Michael.

Yes, that is exactly the prescribed procedure! Of course, the engine should be warm before starting. It then typically revs up to 5200 RPM three times. This is probably not worse for the engine than driving it at full throttle for half an hour. After all, it's only done every two years!

Hello,

Yes, that's essentially correct. The engine will be revved up to the limiter several times, and it will also be held at that RPM for a few seconds.

However, this is not a reason for sleepless nights, provided (and this is important) that the engine is at its operating temperature during the emissions test!
It's not enough for the water temperature to reach 90 degrees; it's better to drive a few more kilometers to ensure that the engine oil also reaches above 80 degrees.

Otherwise, the test is safe, considering that the engine is being revved up without any load.
A 0-100 km/h acceleration would likely be more damaging in that situation.

So: Go there, hold your ears, and that's it.

So, I wouldn't worry too much about 5200 RPM.
As I said, it should be kept at operating temperature.
The reason why TDI engines typically have a rev limiter at around 5200 RPM is because, above that speed, the combustion process becomes very incomplete.
Naturally aspirated diesel engines can easily rev up to 6000 RPM.
I once owned a Toyota Starlet, manufactured in 1985. And when I had to scrap it...
I took the liberty of placing a stone on the accelerator beforehand.
The maximum power output was achieved at 7,400 RPM, and I estimate that it reached...
10,000 transactions have been processed.
After about 5 minutes, the cooler ripped. After about 10 minutes, it...
The melted oil filler cap flew through the air and landed...
I had to turn off the engine for 15 minutes (!!!) because of the neighboring farmer.
has arrived and is looking absolutely fabulous.
What I mean to say is: The motors are more powerful than you might think.

Hi Sevi,

Markus H. wrote:

Otherwise, the test is harmless, considering that the engine is revved up freely (i.e., without load).

Hi Markus,

That's not entirely correct: the rapid acceleration creates enormous forces on the timing belt, which do not occur during normal operation . I would not have an inspection (ASU) performed with a timing belt that is close to its replacement interval .

My skilled TÜV inspector tries to rev up the engine as "slowly" as possible because that reduces the risk of a timing belt failure. However, this means he has to manipulate the measuring device, which takes more attempts, but it's the safer approach!

"Otherwise, I don't think it actually harms the engine, although BMW once had problems with resonant frequencies in the valve springs (I can't quite recall the specifics), which led to the failure of some engines."

Best regards, Christian.

Okay, so, if the doctor messes up the engine, he should be ashamed, otherwise I'll show him what else you can do with a car jack.


What about liability issues if a machine were to explode or break apart? As mentioned above, the speed (and thus the inertial forces) and acceleration involved are not insignificant.

CU Gremlin.

Gremlin wrote:

What about liability, etc., in case a machine falls apart?

Hi Gremlin,

If the jack remains in the car, you "only" have to buy a new engine, otherwise, funeral expenses will be incurred.

Best regards, Christian.

No problem, the pit is already dug.

So, does that mean that if the technician damages the engine, I have to pay for it? I guess I should go oil my chainsaw.

CU Gremlin.

Gremlin wrote:

So, does that mean that if the mechanic damages the engine, I have to pay for it?

Okay! Most of them also have a large warning sign. Because you are responsible for the technical condition of the engine! Or, if you can prove that a workshop made a mistake, then the workshop is responsible if the warranty is still valid!

Best regards, Christian.

Hi,

I would like to know how many diesel engines have experienced a major defect during the vehicle inspection (AU).
In my opinion, even without the AU (presumably a specific authorization or permit), that valuable item would have likely fallen into disrepair shortly thereafter.
And then it's better to be in a hall, rather than at night in the rain on the highway.

'After all, it's a Toyota, and things just don't break on those.'
But our 'German quality craftsmanship'...

Markus H. wrote:

I would like to know how many diesel engines experienced a major defect during the vehicle inspection (AU)...

Hi Markus,

A few years ago, I saw a sign at the TÜV (German technical inspection authority) that said "2 to 3 defects per thousand tests!" But that was back in the days of regular TDI engines, not the "Sensibelchen-TDI" versions. "My" TÜV inspector, who was a bit slow on the gas pedal, found a defect on one car, which wasn't surprising (the timing belt was long overdue for replacement).

Markus H. wrote:

In my opinion, in such a case, the valuable item would have deteriorated and fallen into disrepair shortly thereafter, even without the AU. And then it's better to be in a hall, and not at night in the rain on the highway

.

"If you're constantly driving at around 5200 rpm, that's a problem! For example, the likelihood of a valve spring breaking due to vibrations is highest at maximum engine speed. But in principle, you're right - if the engine is healthy, it should be able to handle it."

Best regards, Christian.

Hi,
A few years ago, an inspector or their employer had to compensate a vehicle owner for a defective engine. However, unlike what is usually done, the inspector had not inquired about the mileage of the timing belt.
"Before a valve spring breaks, I certainly wouldn't be worried about 5200 RPM. That's not a high RPM for a valve train."
Does anyone know how much stress a timing belt experiences when abruptly downshifting? I suspect that higher forces might be involved in this situation compared to allowing the engine to rev freely.

christians wrote:

Does anyone know how much a timing belt is stressed by sudden downshifting? I imagine that higher forces might be involved in that situation than when the engine is allowed to rev freely.

Hi Christian,

This is guaranteed to be the absolute worst . These are also the "transmission specialists" who manage to destroy the engine or the transmission, or various bearings, after only 70,000 km, whereas it would last 370,000 km in other cars.

It would be interesting to calculate how high the forces are . However, a portion of it will definitely be dampened by the slipping of the clutch .

Best regards, Christian.