Hi 

I have a 2009 Fiesta Titanium 1.6 which I love. Best car I've ever had and couldn't live without it. recently it's developed a couple of faults. The first is a rattle under the car when i turn right over an uneven surface that is getting worse. I took it to a mechanic who said it was the exhaust cover which they replaced the bolts on. 

 

Its still there. I don't hear it going forward and very rather going left unless there are lots of pot holes. Any ideas and is it expensive ?

 

the second fault is a spluttering / rustling sound when I accelerate?

 

any help will be appreciated 

Title says 'knocking' but your post states 'rattle'? If it's a rattle it could be a loose exhaust heat shield tapping against the exhaust , if it's a knock it could be a track rod end. From your post I'd go for the loose heatshield.

Thanks russ. 

It's like a bar is loose and when you go over potholes or uneven surfaces it's knocking/banging/rattling. It is in the front end under the drivers side. 

The mechanic I took it in too said they bolted the exhaust shield back up so hopefully they did that :|