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can any one help i've owned my 1999 e39 m5 for 2 weeks and i.m getting a little hesitation when i'm driving at a constant speed when the car is cold and warm and it does it at differant speeds?the previous told me he had changed one of the mafs just before i bought it also i have the coms pack and i can't get the phone to work i press the button for it and the phone lights for a second then goes out
 

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When anything electronic acts up (like the phone in your M5) do what the dealer would do: try disconnecting the negative (ground) terminal from the battery. Wait half an hour and then reconnect. You will need to set the clock afterwards.

About the engine, try testing the MAFs yourself:

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

Welcome to the board!

David
 

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MAFS is a good place to start - Good Luck and welcome to the board:)
 

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MAFs usually go in pairs. If one needed replacment, you might need to change the other too, or at least clean it. (see the link posted above)

Before you go to the dealer with the phone issue, check that all fuses in the rear fuse panel are ok. That fuse panel is located behind the right-hand boot (trunk in the US) cover panel.

As you bought the car quite recently, I hope you have some warranty on it?

David
 

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Discussion Starter #6
thanks davids yes i have a warranty i just needed as much info as i can get when i ring the garage i've also checked the fuses and they are all o'k
 

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Discussion Starter #7
the dealer has now changed both mafs but i am still getting it does any one have any more ideas
 

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craig5 said:
the dealer has now changed both mafs but i am still getting it does any one have any more ideas
Any fault codes being read out? Dealer can read them or you can get a Peake Research tool or equivalent and read them yourself. Check the coils, check the plugs. Good luck.
Regards,
Jerry
 

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Craig,

On some parts of BMWs things can be functioning very poorly without getting a fault-code. I´d suggest to do the following:

1. Check the MAFs as per the link posted earlier in this thread.

2. Have the dealer check the fuel pressure and the alignment of the crankshaft sensor. There should be 5.0 bar fuel pressure at idle with the vacuum hose connected, and 5.5 bar with the vacuum hose disconected. Make sure they test both pressures.

3. The crankshaft sensor should be located 0.55 +- 0.20 mm from the vanes on the fly-wheel. That is a rather tight tolerance, and it has to be met to make the engine run well under all conditions.

It is rather easy to check the alignment (BMW TIS RA 12 14 520):

1. remove the crankshaft sensor from bellhouse.
2. measure depth from seating plane to teeth on the flywheel.
3. measure distance from seating plane of sensor to front of sensor.
4. measure shims if any.
4. add or remove shims between sensor and bellhouse to get a distance of
0.55 +- 0.2 mm between front of sensor and flywheel teeth.

David
 

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Discussion Starter #11
just a update i'm still getting the problem so i've changed the maf twice and it still does it so i now know it's not the maf but i am now getting a fault which say's {right hand air flow signal fault}
 

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craig5 said:
just a update i'm still getting the problem so i've changed the maf twice and it still does it so i now know it's not the maf but i am now getting a fault which say's {right hand air flow signal fault}
Did you clear the fault codes in between?

There could be a connection fault. Are the connectors pushed fully onto the MAFs?

Do the metal part of the connectors look clean and shiny?

David
 

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Craig,

I forgot you are in the UK... oops.

Just to rule out any confusion:
When looking from inside the car in the direction of travel, is it the right or left side MAF?

David
 
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