Throaty Aygo

[john1944]

Just had a new catalityc converter put on the 08 Aygo at 4000 miles, under warranty of course. I am noticing a rather throaty roar when I accelerate from a standstill, which appears to be coming from the exhaust. It is the sort of noise you would exoect from an older car when the exhaust is beginning to go. Any one with ideas please John

[adilmon]

Don't worry, the throaty noise is normal when the VVTi is in action under high load. This is normal. The exhaust note softens when it has gone (e.g.there is a hole in it or a leak somewhere)

I'm assuming that your catalytic converter was replaced under warranty because it was clogged and blocking (and muting) the exhaust gas flow

[john1944]

Don't worry, the throaty noise is normal when the VVTi is in action under high load. This is normal. The exhaust note softens when it has gone (e.g.there is a hole in it or a leak somewhere)

I'm assuming that your catalytic converter was replaced under warranty because it was clogged and blocking (and muting) the exhaust gas flow

Thanks for the reply. Yes the cat was replaced under warranty, within days of me buying the car. John

[Donna_Aygo]

Interesting as I believe my exhaust is making a similar noise and had it checked out at last 30,000 mile service as everyone else says its blowing but Toyota says its fine. Are these exhaust a bit more noisey than other cars and why is this?

[john1944]

Interesting as I believe my exhaust is making a similar noise and had it checked out at last 30,000 mile service as everyone else says its blowing but Toyota says its fine. Are these exhaust a bit more noisey than other cars and why is this?

I will come back in on this one so that every one is clear what I mean by 'throaty' I am not talking about a vroooom sound, it is definitely a blowing sound as described in the previous post. I do get the impression however, that it goes away once the engine has warmed up. In any event it sounds quite sporty; could it be possibly due to the 3 cylinder engine ?

[adilmon]

Are these exhaust a bit more noisey than other cars and why is this?

When a car's design undergoes NVH (noise vibration harshness) testing it's not all about making everything quiet. Some noises, for example, let you know when to change gear or how fast you're travelling.

The VVTi changes the exhaust note and the rear silencer (which uses internal gas pressure waves to muffle the noise) has been designed to allow this to be heard more easily for a sporty sound

NVH specifications all depend on what the design brief of the car is. In this case, idling and normal diving is well muffled and you get an audible reward when you put your foot down :D best of both worlds

Here's more info

http://auto.howstuffworks.com/muffler2.htm

[zakelwe]

Interesting as I believe my exhaust is making a similar noise and had it checked out at last 30,000 mile service as everyone else says its blowing but Toyota says its fine. Are these exhaust a bit more noisey than other cars and why is this?

I will come back in on this one so that every one is clear what I mean by 'throaty' I am not talking about a vroooom sound, it is definitely a blowing sound as described in the previous post. I do get the impression however, that it goes away once the engine has warmed up. In any event it sounds quite sporty; could it be possibly due to the 3 cylinder engine ?

I wonder if it is one of the joins in the exhaust not being totally sealed and when the exhaust warms up and expands it closes up? I think the vibrations from the engine may have loosened it .. just get them to check it out.

Regards

Andy

[Jan van de Wouw]

I'm convinced that's the case on my car: when cold I'm pretty sure I hear the exhaust blow past

the manifold, after about a mile everything seems to have warmed up enough to close the gaps.

Having it checked out at the next (end of warranty) 40k-service...