Hi guys, bit of a weird one but if anyone's got any ideas then I'd be grateful.

I've got a full turbo back Mongoose exhaust on my 2000 Classic which sounds really nice but on a couple of occassions in the last week or so the volume has varied a little bit. I'll try to explain what I mean - usually when I start the car it really roars into life and maintains a really deep rumble whether driving or idling but a couple of times I've started it and its not sounded the same on start-up and the sound while driving/idling has been quieter as well. Anyone got any ideas why this might be happening?

 

How long has it been on the car?

If it has just been fitted they bed in around 700 miles or so, oil and burned cr@p settles inside the system and changes the note, usually dulls it a bit.

Had a mongoose b/box on my MY99, sounded great, fab build quality as well.

 

Cheers for the info Paul, I'm not sure when the exhaust was fitted to be honest, it was already there when I bought the car.

It's just weird because it only happens occassionally. It was like it this morning but if its anything like a couple of days ago, when I start the car after work this evening it will be back to normal again....strange!

 

Is it anything to do with where you park it, could it be the bounceback of sound from solid objects, walls, etc that is making you think the note has changed?

 

no its always started from either outside my house or at work so there shouldn't be any differences in those terms. I even tried cleaning my ears out with cotton buds!

 

My car also sounds quieter some days than others... Not sure what it is, the only thing that seems to vary is outside temperature and humidity.

 

yeah suppose it could be that Henrik. The difference is so noticeable though

 

I have suffered the same thing mate. Its weird, i can start the car and it sounds fine, stop it for a minute or two, restart it and it sounds quieter....... havent a clue why?

 

same here

 

weird hey? had in the garage a couple of times but they cant find anything wrong?

 

yeah its got me puzzled as well!

 

I noticed when it was quiet last time that the idle speed was just under 1000rpm. Is that low? What does a 2000 classic generally idle at?

 

Generaly a classic turbo idles at around between 600-900, well thats what mine idles at. when cold upto 1500rpm till car starts to warm up.

As to the "quieter" rumble its happens with all classic's with full decat, been told by my mechanic, thats its normal for older cars, temp , humidity and time of day.


hope this helps

 

Thats great info mate, cheers for that, sounds like I can breath easy!! Was worried about Maf, Idle switch etc but I (and my credit card) suddenly feel very relieved!

 

It maybe the fueling of the engine guys sometimes my Vortex sounds deeper mainly when it is colder and denser air getting into the engine, I look at the Exhaust temp gauge and its at nearly 800c (which is the highest it reaches) up pipe temp so I put mine down to the fueling. Just a thought.

 

I had an exhaust volume issue with my pug 106 Gti. The garage first suspected the flexible joint in the exhaust as they age (as do the Impreza's). Its perfectly possible for them to make a seal on one day, but then not later on as driving/temp conditions change etc.

In the end it was traced to a cracked recirc pipe. Sometimes it made a seal sometimes not.

Although for this to be true, the exhaust should sound either at a normal volume or louder. It should not be quieter if you are having intermittent issues of exhaust gases escaping.