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Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 21984
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have recently bought 2004 BMW x5 3ltr diesel manual

Customer Question

Hello I have recently bought 2004 BMW x5 3ltr diesel manual noticed that when the engine has been running idle that I can smell fines similar to a"burning smell" and when I start accelerating there's a lot of smoke coming from exhaust I have 2 months of warranty left on it and want to be confident in approaching dealer by suggesting with what the issue might be any ideas what it could be? Also it feels as if what I would have described many years ago as if the choke is stuck or running at too high rpm? :)
Submitted: 1 year ago.
Category: UK Car
Expert:  Matt replied 1 year ago.


to get a lot of exhaust smoke then its likely to be a fueling issue ?

1st check the connections to the EGR valve, if either the vacuum pipe of electrical connection are damaged / corroded then the EGR can be on all time which certainly will hurt performance. Its also possible that its a fault with the EGR valve so its worth removing the valve and cleaning it out with brake cleaner, if it looks particularly clogged then replace it.

If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly

If its a variable vane turbo (they’ll be an actuator on the turbo body - but not a wastegate) then check its vacuum pipework as above and check the connections to the diaphragm / solenoid valve

Also worth considering adding a bottle of injector cleaner into the tank as a clogged injector nozzle will reduce power and give poor combustion - the next stage on from this is to remove all the injectors and have them ultrasonically cleaned and flow checked

Also check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.

Customer: replied 1 year ago.
It isn't a turbo engine would that change anything?
Customer: replied 1 year ago.
Also how could you check if there are swirl flaps on the car?
Expert:  Matt replied 1 year ago.


if its the diesel engine then it should have a turbo? as BMW never made a non turbo diesel engine?

if this is the petrol 3.0ltr then thats a different matter as these did have swirl flaps