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Discussion Starter #1
Lately I have noticed a problem with my '00 model. The power stops builing up (and the torgues is almost fading) @ 4000 rpm on 2nd gear when I throttled hard for acceleration. The situation improves a bit with POWER on but certainly it is no characteristic of the beast. At higher shifts the problems are much less noticeable.

Throttle response was also jerky at 2nd gear before engine warms up, but usually that is within the 1 minute or two when I started the car in the morning so I am not really bothered by it.

I have serached past posts which suggested the possible culprit from (1) MAFS, and (2) stickly hydraulic lifters. Could it be an electronic problem? :confused: I intend to bring it to a tuner but good ones with M5 are rare in the city.

Any similar experience and advice?
 

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I would guess at the MAFs from your description.

Get a good OBD-II fault-code reader with real-time data graphing capability.
You will have much use for this. Those which use a laptop for the user interface cost about US$ 100. Worth every penny, IMHO.

Check if there are any fault-codes stored. If there is a "MAF fault-code" or a "Catalytic converter fault-code", you should definitely suspect the MAFs.

If there are no fault codes, do a road-test. In different gears, check the value of "Calculated Load Value" a.k.a. "CLV". This value should immediately climb to 100% and stay there when you floor the accelerator pedal. If it does not, you can suspect the MAFs.

Search for MAF cleaning. Perform it. If it fixes the problem completely - fine.
If it aleviates the problem just a bit, you want to get new MAFs.

Most M5s seem to need new MAFs every 50000 miles or so.

If you have a K&N type oiled air-filter, chances the MAFs have been damaged by oil deposits are big. In this case you will need new MAFs, and go back to OEM paper air filters.

Hope this helps,

David
 

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Discussion Starter #3
DavidS said:
I would guess at the MAFs from your description.

Get a good OBD-II fault-code reader with real-time data graphing capability.
You will have much use for this. Those which use a laptop for the user interface cost about US$ 100. Worth every penny, IMHO.

...

Search for MAF cleaning. Perform it. If it fixes the problem completely - fine.
If it aleviates the problem just a bit, you want to get new MAFs.

Most M5s seem to need new MAFs every 50000 miles or so.

If you have a K&N type oiled air-filter, chances the MAFs have been damaged by oil deposits are big. In this case you will need new MAFs, and go back to OEM paper air filters.

Hope this helps,

David
David,

Thanks a lot, I'll go about and order an OBD-II fault code reader, can I order it through the 'net?

As for the K&N filters, no I do use them as I have heard conflicting reports about their performance on various generations of M3s.
 

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ODB-2 scantool

Go have a look at

www.obd-2.com

I use their scantool (ISO-version) and their "Carcode" software.
The SW is free, and the hardware costs US$122. You will not need a cable extension option, the standard cable length is adequate.

You need a laptop with an RS-232C serial port. If there is no serial port you can buy a USB-to-RS-232C adaptor from them for US$28.
I bought my scantool from them in 2002. Am pleased with it.

There are lots of different products from different manufacturers. Many are probably just as good as this one, but do make certain you buy one that has data graphing capability, and data logging capability.

David
 
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