I've got just over 50K miles on my B7. It's chipped with full Milltek exhaust. Lately it's been making a sound in the exhaust that sounds like a mild backfire. That is, it doesn't explode but rather makes a sort of sputtering noise. It's typically when I let off the gas. Any ideas?

Thanks all.

 

I was told by my dealer that the 2007 S4 has a timing chain. Therefore you don't need to worry about a timing belt change if yours is a 2007. I have an 07 S4.

 

Bumping this one time. The problem is getting worse and it'll be a bit before I can take it in. Could it be a misfire? It's actually worst when I'm just taking off. It doesn't matter if it's warm or cold - about the same.

 

After some research I was told that this is likely lack of backpressure in the exhaust. The muffler gets worn out and this behaviour starts to happen. Has anyone else had this issue with Millteks? I've narrowed it down to when the car is hot, and the sputtering occurs when it's shifting gears. That makes the backpressure theory make sense to me, but I'm no techie. Kinda sucks if that is the issue - I've had this exhaust for less than 2 years.

 

Sputtering when you shift gears or sputtering when you back off?

If it's when you back off, i believe the backpressure theory, i have been told the same thing also....and have experienced his with other vehicles with straight through exhaust design.

If it's when you shift...maybe that's a different culprit.

 

you're not talking about the regular kinda rumbling popping noise are you?

 

I misspoke originally - it's definitely when shifting (I have a tip). And yes, it's "regular" popping but it's happening a lot more now than it ever did in the past.

 

best thing is to ring milltek...i had my audi 3.0tdi quattro sport avant in there for a new exhuast as a research and development vehicle...and they have told me any problems and we will sort out as the exhaust has a lifetime guarantee...would not hurt to give them a ring

 

Have your plugs ever been changed?

 

No, the plugs haven't been changed, but the diagnostics showed everything is firing fine. It's looking like a leak in the exhaust system. I need to take it back to the shop that installed them but I just haven't had time. I'll go when my tires wear out so I can put on some 235s and lower the front back down. At the same time I want to get the 4:1 differential as I've heard that helps handling quite a bit (more power to the rear wheels). That'll be it for mods unless they come out with a reasonably priced SC that doesn't whine like a banchee.