How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 20592
Experience:  BEng hons Mech engineering, in auto industry 22 years
12772297
Type Your UK Car Question Here...
Matt is online now
A new question is answered every 9 seconds

X5: Matt my x5 black smoke when I accelerate can you help

Customer Question

Hi Matt my x5 black smoke when I accelerate can you help thanks mick
Submitted: 1 year ago.
Category: UK Car
Expert:  Matt replied 1 year ago.
Hello
I'd first 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.
a burst or loose pipe will result in over fuelling and black smoke as you describe
If this Ok then it could be a major engine sensor such as the airflow meter or cam position sensor has failed so that the ECU is now overfuelling or injecting at the wrong point and resulting in poor combustion.
The quickest route to repair is to have the car plugged into a diagnostic machine which will read off the fault code stored in the ECU and indicate which sensor has failed or whether the fault is more serious.
Another possibility is that the fuel filter is blocked so resulting in low fuel pressure and again poor combustion - replace the filter in any case as diesels are very sensitive to this
also check how much oil is going through the breather by popping off the intake hose in front of the turbo and checking for oil deposits. Diesels will run off engine oil so this could also be making it rich
If its been overfilled with oil it will also produce surging as the oil finds its way back into the engine
Expert:  Matt replied 1 year ago.
Hi
do you still need help?