XSeries-forum

The Story so far
The engine warning light came on.  Mixure too lean on the code reader(cheap £30 fron the bay).  Ive changed the MAF but fault flags back up.
I purchased scanner 1.4.0.    The codes say too rich plus a few misfires.
Cleared these faults several times and fault then comes up agaiin.  The car drives fine.  Plenty of power and no misfires.  Seams to be on idle faults occur.
This is starting to naf me off so changed back to old MAF and still the same.
Interesting observation.  Stood over engine and sounded great.  Reved a little then an obvious air leak developed.  Sounds like an air compressor cycling you have for air tools.  It started to get worse and engine light came on.
I cannot see or feel where its leaking.  There are a few pipes that come off the inlet but ive put my fingers around all of them but it sounds like its further in or a valve leaking.  Is there a engine breather around here.
Is there a culprit like the hedgehog that throws this up
Scanner 1.4.0 great,    it showed the maf at a steady 15 kg until this fault occurs then the spark advance goes all over the place.
It looks very tight around the inlet area.  Can covers be taken off to show idle valve etc
Thanks
Id take it back to the w---kers that said it was the maf but i would trust them to change a filter on a lawn mower

Give us a clue, 3.0i, 4.4, 4.6 or 4.8 ????
Is it a leak, positive pressure or a vacuum noise, if it is saying you have a too lean a mixture, and the MAF is reading out. It seems more likely to be a vacuum you can hear. The Mass air flow meter reads how much air is being drawn into the intake system, then adjusts the amount of fuel via the fuel injection to obtain the correct mixture. this is then burnt in the engine, once burnt it then proceeds through the exhaust past the O2 sensors ( lamba sensors ) this then identifies if the mixture is correct.
If more air is sucked into the intake of the engine AFTER THE MAF it will not be metered in to the equation, so the amount of fuel dished out by the fuel injection system. So the mixture ends up too lean. Lamba sensor sees there is a problem and puts on the EM light, system identifies that the MAF must be reading the airflow incorrectly.
but the MAF is reading only the air that has passed over it not the air that enters the system through the split intake hose, or split in the intake manifold. (

Sorry its a 3.0i petrol sport.  Im grateful for the info above but i was hoping someone may be able to point to a known area around the inlet thats leaks and throws all these faults.
The inlet pipe to the throttle body has bellows and behind this is another lump thats attached to it under the rad couling.  Does this split ? and how do you get it off.  Does the couling have to come off first ?

It's is a common problem with the 3.0d, the bellows or intake pipe that splits off to go to the idler valve is a common place to split . Spray easy start on the pipes when the engine is running( remove the top engine cover )
The vacuum will pull in the easy start and rev the engine.
There are old posts that cover this topic if you troll through the past posts.

http://xdrivers.co.uk/forum/https://xdr ... ic.php?t=0

An Update
Ok now we have some results.    Firstly it wasnt the maf.    It was a leak in the DISA valve or adjuster valve that goes on the air intake manifold.    I say a leak but im going to take it off tomorrow and inspect for myself what it looks like and whats been done with it.
I conclude that its the DISA from the start and has the same symptoms as a split inlet hose.  I think mine was just leaking around the seal. 
The £30 maf off ebay works a treat and no troubles.  So dont be put off by the price.  Pattern MAFS from my local trade factors were £150 +VAT , but i bet they came out the same factory.   
I may need a new DISA valve.  Where is the best place to buy one as this has to be BMW i suspect.

http://www.ebay.co.uk/itm/BMW-DISA-Valv ... 257b714e56

Try this, looks as though a common problem with the M54 engine

I had a look at that.  I took the DISA  valve out and was a bit shocked at what the indy dealer had put back.  The flap was a flappin and the pin was very loose and about to come out.  If id left it then it would have been new engine time.  what a bunch of W---kers.  As it was far gone i decided to go and get a new one from the swanky new dealers at Elms Cambourne.  I pushed for trade price and got it at £202 inc VAT
Im registered for VAT so i get that back.
Car now drives great no codes coming up.  I've made a voodo doll of the dealer and have sent a few spells to send him on his way down an imbankment

The £30 maf off ebay works a treat and no troubles.  So dont be put off by the price.  Pattern MAFS from my local trade factors were £150 +VAT , but i bet they came out the same factory.   

Those words will come back to haunt you