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Discussion Starter #1 (Edited)
Hi All,

I'm wondering if the experienced minds on here can help me with this fault code. At the moment, the car isn't showing any symptoms, but keeps throwing the 27D0 fault "Fuel pressure control adaptation" when I scan with DIS. Being slightly OCD about keeping everything right, I want to get this fixed. I previously had a problem with the car going into reduced power / limp mode - this was solved by changing the coolant thermostat (code was present for stuck thermostat).

However, I can't get rid of this last 27D0 fault. So far, I have changed the fuel filter which was really dirty, but it hasn't cleared. Tonight, I ran the DIS fuel system test after re-setting the adaptations first, then cleared the fault code and had the following results (see pics). Note the "Not OK" indicated twice. You can also see that the fuel pressure is reading 3.8bar - this was at idle, and the setpoint should be 2.9-3.1bar. Could the fuel pressure sensor be faulty as it appears to be reading high? Or do I need to change the fuel pump? No leaks as far as I can tell, I was planning on changing the injector O-rings next to see if it makes any difference.

Also, perhaps someone can explain what the delta pressure "Not OK" is all about....
 

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Discussion Starter #2
^Bump^ - Anyone??
 

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^Bump^ - Anyone??
No direct experience, but since it is going over, I would suggest your pressure sensor is providing you with a too low reading relative to what it really is, and thus the system would compensate by providing more pressure. But the catch is that these readings are coming from the suspected faulty sensors. So, perhaps you can hook up an external pressure sensor and verify as a first step what it -really- is?

Assuming that the pressure is correct, then I would suggest to check the fuel pump. The pump is controlled by a pulse width modulated signal, along with a high pressure pump which comes on above a certain fuel demand. The pump may not be controlled correctly anymore, so I would suspect the pump electronics next. How many miles on it?
 

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Discussion Starter #4
Thanks for the reply.

It has 60k on it. I forgot to mention, I already changed the EKP Fuel Control module from one out of a newer M5, but no change. So it looks like I'm left with checking the fuel pump and pressure sender next. I know which one is cheaper to replace!

I'm doing a track day next Thursday and really don't want the fault to develop into a "reduced power/limp mode". It's never done it on the road, but I know these things can show a lot more when the car is pushed to it's limits.
 

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Discussion Starter #6
Quick update - no problem with any of those fuses so it looks like it's the pressure sensor or the pump at fault. However, I've just had the car on the Dyno and no problems reported with fuelling. It made a fairly healthy 438hp (see my other post).

I'll see if I can get a fuel pressure gauge hooked up and see if the sensor reading is true, and just go from there.
 

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Discussion Starter #8
any updates on that? I am having both 27D0 and 27D6
Unfortunately I've not had the time to diagnose this one further. I was in a rush to get the car ready for a track day at Silverstone, so following the positive results on the dyno, I took the risk and did the track day. The car still shows the 27D0 code, but I didn't have any running issues - in fact, it was running the best it ever has.

Prior to changing my fuel filter, I would get the "Engine Malfunction - Reduced Power" fault at high RPM. The old filter was very dirty. What other symptoms does yours have?
 

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I have a whining sound when I am accelerating or pressing the throttle at idle, the idle is rough, I am also getting a Reduced Power which is because of these 2 fault codes
 

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Hi every one am having same error on my M5 ot has 72k of milage on it
Already changed fuel pump the fault is still there looked at all fuses and other relays and it still there can it possibly be the fuel pressure sensor and how can i be sure if it was the sensor giving fouls reading

another question how many bars should it reads on idle
&
How many bars it should read on full throttle

thanks
 
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