Boost surge (06-12-2004, 20:41)

Hi!
I have another question about the results of a measurement run. I used VAG-Com to do a very detailed analysis on my colleague's Bora, and I noticed that the boost pressure was slightly negative. Now, I would like to ask you experts for your opinion. Specifically, this AHL Bora always exhibits overboost with maximum values of up to 2.5 bar . Since it hasn't been chip-tuned or anything else, and it's a 90 hp engine, that seems a bit too much to me.
Here's the translation:

"What is particularly striking is also the extremely aggressively acting charge pressure limiting valve (see graphic - blue line). Since the AHL [presumably referring to a specific system or component] doesn't have a VTG either, I think the valve itself is more likely the cause. Or am I mistaken "

By the way, the graph looks the same in several measurement runs. So, the 2.5 bar reading wasn't just a one-time anomaly...

wbuchi82 wrote:

Specifically, the AHL Bora experiences overboost situations with pressure surges reaching a maximum of 2.5 bar . Since it hasn't been chip-tuned or modified in any way and is a 90 horsepower engine, this seems like too much to me.

Well, pressures up to approximately 2.2 bar (absolute!) are considered normal.
Der Motor heißt eber wahrscheinlich ALH, oder ?

Quote:

The extremely aggressively designed wastegate valve (see graphic - blue line) is also particularly noticeable. Since the AHL doesn't have a VTG either, I think the valve itself is more likely to be the cause. Or am I wrong

Yes, you are seeing something wrong:
1. Does the ALH have a VTG loader?
2. Is the "aggressively reactive" behavior of the valve simply a reaction to excessive pressure?

Quote:

The graph looks the same in several measurement runs. Therefore, the 2.5 bar is not a one-time anomaly.

I suspect the variable geometry turbocharger (VGT) or the solenoid valve is stuck... or (less likely) the VGT rod is incorrectly adjusted and too short.

....tja, ist natürlich der ALH gemeint ....... bei dem vielen Varianten komm ich ab und zu durcheinander....

The ALH actually already has VTG . Then I made another mistake...
I thought the 90 horsepower engines didn't have a VTG system yet – only the PD engines did... but believing doesn't mean knowing , and I haven't gotten under the hood to check.

Then I should probably do that and check the VTG (Variable Turbine Geometry), or possibly replace the valve as a test.

Sure, here is the translation of the text from German to English:

"MFG" stands for "Mit freundlichen Grüßen," which translates to "Sincerely" or "Best regards" in English. It is a common way to end a formal letter or email.

After installing my LDA (Lambda-Probing Device), I also noticed that my Golf's overboost pressure sometimes reaches up to 1.5 bar. However, this only happens occasionally; otherwise, the overboost pressure maxes out at around 1.2 bar. I haven't bothered to check how easily the VTG (Variable Turbine Geometry) adjustment moves yet... unfortunately, that requires getting under the car again.

The ALH actually already has VTG .

yepp... the rumor persists stubbornly, even among those who are directly in front of it and see it happening .

'Mine has been doing that kind of over-expansion (1.2 bar) from the beginning.'

CU Gremlin.

Overshoots can also occur even when the maximum LD value in the dataset has not been increased.

That's how you damage the battery in stop-and-go traffic with the constant overcharging...