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Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 22740
Experience:  BEng hons Mech engineering, in auto industry 22 years
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my 2006 audi a3 sportback has a slight misfire when starting

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my 2006 audi a3 sportback has a slight misfire when starting up but seem ok when on the road there is also a stronger smell of fumes. just recently i had some work done to it a new timing belt, water pump and a lamda censor not going same.?

is this exhaust or fuel fumes?
also how does the car drive with the fault?

any problems accelerating or poor idle speed control?
Customer: replied 4 years ago.

Hi Matt

it is exhaust fumes when idling the needle on rev counter going up and down accelerating ok and seems to run fine. also noticed if go back into garage after using car strong oil smell?

regards ewan

Hello Ewan

Check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.

this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst

The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers
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