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Enes, Volvo Master Technician
Category: Volvo
Satisfied Customers: 5557
Experience:  18 yrs+. experience as Volvo & ASE Certified Master Technician.
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1993 960 6 cylinder 3 litre keeps burning out catalytic converters

Customer Question

1993 960 6 cylinder 3 litre keeps burning out catalytic converters and fails emission tests. Suggested that as result of rich mixture and/or slight misfire at idling speed. Any ideas on how to adjust mixture as tailpipe shows rich exhaust (black & sooty). Could mixture also cause misfire?
Submitted: 4 years ago.
Category: Volvo
Expert:  Enes replied 4 years ago.

Enes : Hello and welcome to our web page here my name is Enes I'm a Certified Volvo Car Expert Mechanic.I'm going to try today to answer your question.
Enes : you must check fuel pressure and oxygen sensors they go bad and can do that
Enes : check vacuum or air leaks fix if any
Enes : replace spark plugs if they bad and check coils for spark plugs each spark plug has own coil
Enes : Misfire is most the time bad ignition coils
Enes : than fuel pressure bad
Enes : vacuum leaks at Intake
Enes : also hooking up scanner will help read fault error codes
JACUSTOMER-ci4314ek- :

Did not answer question regarding mixture. New plugs fitted. Vehicle pulls well with no misfire on acceleration. Only slightly discernable tremor at idling speeds.

JACUSTOMER-ci4314ek- :

As above-answer not complete. Garage now replacing the catalytic converter again! At least this should ensure the car gets through its MoT and give me time to resolve the problem and still drive the vehicle.