CEL - big cloud of smoke @ high rev - spudder on acceleration
01-05-2014, 12:23 PM
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CEL - big cloud of smoke @ high rev - spudder on acceleration
hey guys,
i recently purchased a 08 a4. the car has been great, but now im running into problems.
ive done a tune up.. spark plugs, oil etc... lately ive been getting this huge cloud of black smoke when i gun it, misfires, and when i accelerate it stutters a bit.
from past experience, can someone please guide me in the right direction as to what i should be looking for under the hood?
PLEASE HELP!!
i recently purchased a 08 a4. the car has been great, but now im running into problems.
ive done a tune up.. spark plugs, oil etc... lately ive been getting this huge cloud of black smoke when i gun it, misfires, and when i accelerate it stutters a bit.
from past experience, can someone please guide me in the right direction as to what i should be looking for under the hood?
PLEASE HELP!!
01-14-2014, 06:33 AM
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It may be as simple as the air cleaner element.
If the filter is blocked up you won't be getting adequate air flow to get good fuel mix, so what hits the pots is rich - hence the smoke at high revs.
Ovbiously, if you changed teh filter at service, check teh entire air intake pathway for obstruction.
You don't spec which A4 you have, so you may need to check turbo, ducting, intercooler etc...
Other nasty option may be that the cam belt may have jumped a tooth. So with the advance on high revs (assuming this is a petrol engine) you're not getting ignition of the mix in the cylinders, because the exhaust valve is already open...
Also, check timing and electrics. Thankfuly we don't have to worry about distributors and rotors these days, but check the TDC sensor and HT leads.
HT leads do NOT give a zero impedence (unless made of cheap chinese copper wire), and impedence will vary with length.
Put a multimeter on the lead, and flex the lead. Impedence should remain constant. Otherwise, lead is faulty.
Good Luck
If the filter is blocked up you won't be getting adequate air flow to get good fuel mix, so what hits the pots is rich - hence the smoke at high revs.
Ovbiously, if you changed teh filter at service, check teh entire air intake pathway for obstruction.
You don't spec which A4 you have, so you may need to check turbo, ducting, intercooler etc...
Other nasty option may be that the cam belt may have jumped a tooth. So with the advance on high revs (assuming this is a petrol engine) you're not getting ignition of the mix in the cylinders, because the exhaust valve is already open...
Also, check timing and electrics. Thankfuly we don't have to worry about distributors and rotors these days, but check the TDC sensor and HT leads.
HT leads do NOT give a zero impedence (unless made of cheap chinese copper wire), and impedence will vary with length.
Put a multimeter on the lead, and flex the lead. Impedence should remain constant. Otherwise, lead is faulty.
Good Luck
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