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Ask Neal Your Own Question
Neal, Mechanic
Category: Volvo
Satisfied Customers: 8351
Experience:  Shop Owner all around Auto Repair and Classic Car enthusiast.
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We have put new coils and a new catalatic converter and new

Customer Question

we have put new coils and a new catalatic converter and new volvo spark plugs
and the car is still mis-firing??
Submitted: 2 years ago.
Category: Volvo
Expert:  Andy replied 2 years ago.


My name is ***** ***** I am a Volvo dealership technician. I am going to try to help with your question today. What cylinders are misfiring? What fault codes are stored? Did you verify the coils were not firing or was that just a guess?

Customer: replied 2 years ago.
We verified that all 4 of the back coils wernt firing so we replaced all to be safe...and i dont remember exactly the codes showing up but we have been going through everything
Expert:  Andy replied 2 years ago.
this is a V8, correct?
Are the rear coils firing now or are they still not working?
Customer: replied 2 years ago.
Still not working
Expert:  Andy replied 2 years ago.

How are you checking the coils?

Customer: replied 2 years ago.
We had it hooked up to a code reader and also had them off and checked it
Expert:  Andy replied 2 years ago.

A code reader cannot tell you if the coils are working. Just because there are misfire codes does not mean the coils are not firing. How are they being checked off the car?

Customer: replied 2 years ago.
I just have them off and i am using a coil test light.... I had one mechanic down here say it could need a new main wire harness and that could be causing the miss fire...what do you think?
Expert:  Andy replied 2 years ago.

I am going to have to opt out. I don't think I will be able to help you with this. The question is opened to all other experts. If one feels they can help, they will respond here.

Expert:  Neal replied 2 years ago.

What codes were you getting? Have you ruled out vacuum leaks or other possible causes?