525tds: Power Loss Troubleshooting Guide

Hello,

I'm not sure if I'll be able to understand the answers to my post, given all the abbreviations like VNT, AFN, ASV, ALH, etc. I almost failed the introductory questions for the forum, but I'm just stuck with my vehicle and the problems I'm experiencing. Here's my description:

Ich fahre so auf der Autobahn (140-150km/h) 2000-3000upm. Beim Kickdown schaltet das Automatikgetriebe runter. Die Drehzahl geht bis ca. 5000upm. Dann wird hochgeschaltet. Auf einmal bemerkt man einen Ruck und man meint das Fahrzeug würde festgehalten. Ich brauche ca. 5-10 Km um auf die 180km/h zu kommen, an mehr ist nicht zu denken. War dann bei meiner Werkstatt und habe den Fehlerspeicher auslesen lassen. Waren zwar mehrere Einträge drin wie AGR Ventil, Getriebesensor, Ladedruckregler. Ich habe dann mal alles Löschen lassen und wieder ab auf die Bahn. Und wieder bei ca. 160km/h: Leistungsverlust, Verbrauchsanzeige fällt von 22Ltr. auf 15Ltr. und der Motor quält sich bis auf 180km/h. Dann wieder zum Auslesen. Fe"More entries:"

Error 101 - Turbocharger pressure control.
Error 10 - Injection timing.
Error 6 - EGR System.

"I then found a few damaged vacuum hoses. For example, the black hose from the AGR valve to the engine block was torn. I replaced it. Also, the hose that runs from the intake manifold to a pressure sensor (???) was torn off, and I replaced that too. Now it runs at 180 again, but it still doesn't rev higher than 3500 RPM in the highest gear. What I also noticed is that when the engine is revved above 3000 RPM, there's a whistling sound coming from the front of the engine bay. But only when the vehicle is moving, not when it's stationary. Does anyone have any suggestions for what I can check?"

Oh yeah... It's a 1999 BMW 525tds.

Regards,
Ralph.

Okay, then you need to figure out where the whistling sound is coming from. It could be from the turbocharger, which might be damaged, or you might have a leak in the boost pressure system (intercooler, hoses, etc.).

"Since so many hoses have already broken, it's possible you might have missed one. Also, check the thicker hoses; they might look fine when the engine is off, but once there's boost pressure, they can start to fail. Look for any signs of oil leaking, as that could indicate a boost pressure issue."

Sounds like a turbocharger boost leak. Check everything as described, which also seems consistent with the error.

ASN, ASV, ALH, and other engine codes like ASZ, ARL, AWX, AVF, and AXR are engine codes used in vehicles manufactured by VAG (Volkswagen, Audi, Seat, and Skoda).

VNT = I can't say that either.

VTG stands for Variable Turbine Geometry, which refers to a turbocharger with adjustable turbine blades.

matthiasTDI96 wrote:

VNT = I can't say that either.

Variable Nozzle Turbine

Hello,

"Thank you very much for the tips. The turbocharger boost hoses are already very oily. I've cleaned them and now I want to see where the contamination is coming from. But still... If it's the hoses, shouldn't the engine also whistle when it's stationary if you rev it up to 3000 RPM? I don't understand how the boost pressure could be different when the car is stationary compared to when it's moving."

Regards,
Ralph.

Ralph S. wrote:

Hello, "Thank you very much for the tips. The turbocharger boost hoses are already very oily. I cleaned them and now I want to see where the contamination is coming from. But still... If it's the hoses, shouldn't it also whistle when the engine is idling if you rev it up to 3000 RPM? I don't understand how the boost pressure could be different when the engine is idling compared to when it's moving." Regards, Ralph.

It's quite simple: boost pressure only builds up when you demand power from your engine. For example, if you're driving up a hill in 3rd gear at 2000 RPM with full throttle, you'll have full boost pressure. However, if you're driving down the same hill in the same gear without using the accelerator, you'll have almost no boost pressure. When idling, there's no load on the engine, so you can't expect to have any boost pressure. You can create a little bit of boost pressure by having someone repeatedly press the accelerator pedal, but it probably won't be enough to find a leak, unless it's a large leak.

To understand this, you need to know how a turbocharger generates its pressure. Then you would also realize that at idle, at 3000 RPM, there is only a very low boost pressure. The turbocharger draws its energy for pressure generation from the energy of the gases flowing past its drive side, and this energy increases with the amount of fuel injected. At idle, at 3000 RPM, only a minimal amount of fuel injection is necessary.

So, you can't hear anything.



Okay, I'm stupid, I thought VTG meant VNT.

Thank you. This is helpful for now. I will proactively replace the hoses. I will get back to you after the replacement.

Regards,
Ralph.

Tja.....die Schläuche waren es wohl nicht. Habe beide gewechselt (ca. 50 EURO). Der mit dem zweiten Schlauch dran, der zum Luftfilterkasten geht, sah schon sehr verölt aus, aber das Pfeifen ist nocht da. Ich bin dann zum Freundlichen gefahren. Kleine Probefahrt. Auch seiner Meinung nach verliert der Turbo Ladedruck. Ich soll mal den Ladeluftkühler ausbauen und ihn nach Steinschlägen und Lecks kontrollieren. Wenn ich nichts finde, den LLK mal mit Wasser spülen und sehen, ober er undicht ist. Das wird dann meine nächste Wochenendarbeit sein. Ich I'll get back to you...

Regards,
Ralph.

"Okay, so the hose from the air filter to the turbo isn't a pressure hose, it's a vacuum hose, because it's on the intake side of the turbo. To check the boost system, you should start with the other hose that leads away from the turbo, goes to the intercooler, and then ends in the intake manifold. Of course, it's possible there's a blockage in the intercooler. Before you spend more money on parts that might not be faulty, consider buying a boost gauge and observing it. This will help avoid further speculation. On your way to the parts store, you could stop by a car wash and do an engine cleaning (be careful not to use cold water on a hot engine, as this can cause problems). Once everything is clean, it's easier to find leaks."

Hello Matthias,

Buying a boost pressure gauge?! That's probably going to be really expensive, right? And how does it work, or where does it get installed?

I have absolutely no idea about that.

Regards,
Ralph.

Please use the search function; there are suitable options available for under 50 euros, and it must be connected to the car's boost pressure hose. You might also want to search in a BMW forum to see how they solve this issue.

There are probably at least 200 comments on this already... try typing "LDA".