Morning all, I've owned my 66 plate for 12 months and just had it's first service via Essex Ford a couple of weeks back.  It's a 1.5 DCI but since buying the car I've been really impressed by how quiet the car  has been.....or at least I was until it was serviced. 

Over the last fortnight the car has been making noises that I swear were not there before.  A small but always there buzzing noise when driving at lower speeds or when sitting in traffic - a much harsher, "boy-racer" type noise when accelerating from about 20-30mph.  I have taken it back to Essex Ford, who by their own admission only carried out some visual checks and a short road test, but they're claiming to have heard no abnormal noises. 

Any thoughts or comments gratefully received.  Given they've only changed filters, oil, etc is there anything that could potentially cause this sort of noise?

Many thanks

Pete 

Lose engine cover?

Really the only filter likely to add throttle noise is the air filter.

It's possible that the old air filter was pretty dirty and blocking some of this noise, as the dirt builds up gradually you don't notice it getting quieter although it's perfectly normal.

It's also possible that the filter box or piping hasn't been sealed properly - have a look at them yourself and you should see any minor gaps between the box halves or pipe connectors etc.

hole in exhaust maybe

Have you noticed increased mpg?

The old induction filter may have been restricted with leaves and insects causing a reduction in noise aswell as response,

There's less restriction with the new filter, 

Ow I see Tom got there before me lol 

Plus one 

Thanks for all the responses.  Whether this makes any difference but believe the car is actually a 1.5 TDCI so I guess running normally the car should make a little more noise that I was used to.  I'll check the filter box to ensure it looks properly sealed and keep an eye on the MPG as well.  Appreciate everyone taking the time to respond - will update as to the eventual conclusion reached.