730d turbo(?) noise and lack of power

[Rik Gruwez]

Hello all,

Sorry to make this mail in English, but I do not speak or write German. I have an E38 730d, model year 2001. Since a couple of weeks, the engine makes a funny noise between 2,500 and 3,500 rpm. It is hard to describe this noise. It is not really a whistling noise coming from the turbo, but rather more of blowing noise, as if you would be driving with one of the doors ajar. The car also lacks power and feels sluggish, ever since the noise started. On the speedometer I can hardly reach 200 km/h. Before the problems started, I could easily get to 220 km/h. Yesterday the BMW replaced -- under warranty -- the turbo because they assumed this was the culprit of the problem. However, the situation remained unchanged. I test drove it this morning and still the engine feels sluggish. Top speed this time was 195 km/h.

The dealership is at a loss and the BMW representative for Belgium also does not know what is wrong. The did a full readout of the error codes using their diagnostic computer, but could not find anything wrong.

Does anyone know what could be the cause of my problem? You can reply here on the forum in English or in German, or mail me directly at gruwez@libertysoftware.be.

Thanks,
Rik Gruwez
Brugge, Belgium

[Erich]

you are not the only one with a problem, it seems.
klick above the function "Suchen". then type under "benutzername" the word "brinki" and then klick "suchen".
there you will find several threads about this problem.
maybe this helps you.

[Rik Gruwez]

Thanks for the tip. I have reviewed the other articles related to the similar problems. My German is not that good to understand everything they say. Basically what I have found is:

1. If the turbo is not to blame (which it is not in my car) then it can be the "Luftmassemesser" or LMM. If the LMM is faulty, would this not show up on the diagnostic readouts the dealership does with their computer?
2. Some posters suggested that using winter diesel can cause this. Is this really true? I mean, if winter diesel makes my car feel sluggish, it should happen to a lot of other cars as well, right?
3. A weak battery apparently can cause the engine to switch to a emergency program or "Notprogram". If this happens, will this condition be stored as in error code in the car's diagnostic module?

Thanks for the feedback,
Rik Gruwez
Brugge, Belgium

[LU223]

Hi Rick,

sorry to hear that you have trouble with your 730d. I have a 99 model and experienced only problems with the air flow sensor (LMM) which had to be replaced several times.
You are right by assuming that most problems should be recognized by the diagnostic tool.

I would check two other things:
First, does the engine get the right amount of air or is one of the air guides/spoilers blocked or not guiding the the air properly?
Second, the pressure of the fuel injection. I do not know if the the fuel injection is totally checked by the diagnosis system.
Third, the exhaust pipe system should be checked also since increased pressure in the system affects the power of the engine.

I can not imagine that the diesel sold at brand gas stations in Europe will have an impact on the engine. Perhaps with certain kinds of Biodiesel.

I do not know if I could be of help. But keep us posted, because any known source of problem can help somebody in the future.

Greetings to Brugge

Michael