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Discussion Starter · #1 ·
Hi,

I am brand new in the BMW M5 world and totally novice in mechanic. I just acquired an amazingly clean M5 mod 1999. It has only 45,000kms and was parked most of the time in a garage (the previous owner was a pilot for Gulf Air airline).

I checked the whole car through the local dealer and even did a main maintenance to be sure everything was ok on the car. They confirmed that the car was fine. However, I have one concern:

The acceleration is not frank and have little "holes" during smooth acceleration. Also, if I accelerate full throttle, I feel that the car does not give all the power it has. For instance, sometime, just by releasing the accelerator a little bit, more power is being delivered for a couple of second.

All filters have been changed, as well as all the spark plugs.

Does anyone have felt the same thing on their M5? I would really appreciate your help! I related my issue to the Power loss thread (http://www.m5board.com/vbulletin/showthread.php?t=54692) but I am not sure. My dealer does not seem to know what is going on and told me everything is fine. I am now thinking of simply changing the MAFS but I would like to make sure this will cure my problem...

Thanks in advance to all of you!

Pascal
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Pascal

Clean the Mass air flow meters (MAF). I had the same issue, but after I cleaned both MAFS, the car is amazingly fast again. There is a lot written about this issue in this forum. Do a search on MAF or LMM.

BR
Ice
 

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Discussion Starter · #3 ·
Thanks Ice,

I will start with a simple "cleaning operation" as posted earlier and will see the difference. Do you think changing the MAF is required anyway? I have no idea what the cost is for those things...

Pascal
 

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Congratulations to your new ownership. The first bacth of RHD (?) E39 M5s have some minor issues that were fixed in later years but other common ones are repeatedly discussed in this board.

For a test of the MAF perfomance refer to the latest posts initiated by DavidS

http://www.m5board.com/vbulletin/showthread.php?t=54788.

His other threads on the topic are also excellent reference/studies worthy of your reading.

Ambient temp could be a factor in your country, for that take a look at the temp effect on the the car by going thru Greg's series starting from

http://www.m5board.com/vbulletin/showthread.php?s=&threadid=34815

Hesitated acceleration on WOT are not uncommon and I am still trying to adpat myself to the situation after owning a MY99 M5 for more than a year. If you experience occasional misses another area to look is the fuel line system, including the fuel filter, the fuel pump, and the O2 sensor.

Early models also have problems with leaking differential gaskets. At least mine inherited it from the previous owner, you may want to take a look too.

Good luck and happy driving! :wroom:
 

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Enjoy your new car, and I have never priced MAFS but I think I heard someone say once that they are around 300 USD apiece, but hey I could be wrong, Josh
 

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Discussion Starter · #7 ·
Thanks to all of you guys!

Thanks to my local workshop manager, I managed to get new MAF installed and tried before paying anything. He had a technician installing the new MAFs and we went for a small ride around the corner: smooth as heaven! Now, the acceleration is really nice and no holes at all. I did try WOT, but not to high RPM (max 4K). It drives like a charm: Thanks Azzam!

Now after finalizing the deal (another thanks to Azzam who gave me a great deal on those MAFs), I left the workshop and drove back home. I just tried to go over 4K once, but it seems that the engine did not want to rev. I guess I have to wait about 100kms for the ECU to reset itself and get use to the new MAFs. Am I correct?

Further than this, Azzam did check everything on the car and confirmed that there was no leak or anything. So I guess I found a nice one. Next step I will go with is to install the Nav system.

My feeling so far is that the M5 should be considered as the car of the century!

Cheers!

Pascal
 

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I had the Mafs replaced last year, and there was no need to wait for anything. They worked great right after they went in.
 

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perrotpx said:
I just tried to go over 4K once, but it seems that the engine did not want to rev. I guess I have to wait about 100kms for the ECU to reset itself and get use to the new MAFs. Am I correct?
Hello Pascal,

The engine not wanting to rev could be that the old MAFs were so bad it will take a while for the ECU (DME in BMW language) to learn to new MAFs.

(When I had the MAFs changed on my car it took about 25 km, before i got full power.)

Were there any fault-codes stored in your car?

When you have driven 100 kms, would you like to post here how the car has changed, please?

David
 

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You have to disconnect the battery in the trunk when performing a job like this. And this is mainly because of resetting the ECU and to avoid any damage. You can do this afterwards also, in order to reset the ECU. Just diconnect it over nigt and reconnect it again in the morning and the engine performance will be solid.
 

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Discussion Starter · #11 ·
I sure will post the end result David!

I wish I read your post last night IceGBG. I will disconnect it now for about 1hr. I hope it will be enough (I used to do this on my Stealth and 15mn were enough to reset it).

Will keep you posted.

Pascal
 

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Discussion Starter · #12 ·
Hi Guys.


I did disconnect the battery for an hour this morning. I went for a smooth ride after this for about 50kms. It was running very smoothly and I did not use any power (less than 4K rpm).

After 50 clicks, I decided to try it again. I am amazed! Rock solid acceleration from top to bottom. Smooth, powerful, soooo nice!!!

Next is the NAV, and then I will see.

Thank you all for your help and advices,
Pascal
 

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Wonder if disconnecting the battery would cause any other memory settings to reset to default? Say, radio stations, seat positions, etc.
 

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Discussion Starter · #15 ·
Only ECU, time, date and odometer as far as I am concerned. Everything else was kept in memory (seats and radio stations). Keep in mind that I just disconnected it for one hour. Apparently enough for the ECU (and made a huge difference).

Cheers
 
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