BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

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X5_NGATE
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BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

Mon Feb 11, 2019 2:14 am

Hi,

I have an BMW X5 2008 3.0TD 270,000km with DPF removed and EGR turned off in computer.

Have an intermittent problem e.g:

Accelerate from stopped
reduced boost
very sluggish acceleration
if depress accelerator more, heaps of black smoke (unburnt diesel) from exhaust
then get to 60km/hr very slowly
Set cruise control to 60km/hr
car slows down to 40km/hr going up hill
cruise control tries to accelerate but no boost, again heaps of black smoke (unburnt diesel) from exhaust
Stop car for 10min,
Restart, acceleration better, still some smoke
Drive upto to 100km/hr, car now accelerating ok, no smoke

This problem appears to happen when the ambient temperature above 30 degrees celsius or car has been stopped sitting in the sun for a couple of hours.

Engine Codes recorded: 3FF0 Air Flow Mass Meter, 4B1C Fuel Filter Heating Activation, 4251 Glow Plug Cyclinder 5 Activation

Attached are engine data graphs while the poor acceleration, black smoke is happening.

Has anyone seen this problem before? Any guideance will be greatly appreciated

regards

Tom
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Re: BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

Mon Feb 11, 2019 6:43 pm

If the MAF has gone faulty then the engine computer will be getting bad data. That could cause over-fuelling or incorrect mixture leaving to smoke.

Glowplug 5 has failed and needs replacing - needs doing with great care as my X6 needed 7 hours of work to fix snapped glowplugs just last week. If you are doing them then it’s a good idea to change the preheater controller at the same time,

Fuel system has a pre-heater to stop the diesel fuel ‘waxing’ in low air temps. The fault code suggests that has failed as well. This would cause fuel starvation.
:ant: Never anthropomorphise computers. They hate that.
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Leslie
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Re: BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

Mon Feb 11, 2019 11:10 pm

Can you just unplug the airflow meter on these like you could on a 330d and see how it goes ? couldn't run any worse by the sound of it ...
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LincsX5
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Re: BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

Fri Feb 15, 2019 5:05 pm

I’ve had very similar symptoms on my 08 3.0D and it was due to over boost because of a sticking turbo wastegate. Although that chucked a fault code for overboost too.
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marti
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Re: BMW X5 2008 3.0TD: Reduced Boost on Acceleration and unburnt Diesel out of exhaust

Fri Feb 15, 2019 5:37 pm

The MAF reading looks way over as its over 1050C , MAF readings should be +/- 2C of the ambient temperature, I presume you live in a warm country, so as the ambient temp is 35C it shoud be reading 33 to 37C for the intake temp.

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