Is popping on overrun a problem?

[MagicalTrevor]

I'm sorry this has been covered before, I just don't understand the technicalities.

My K series Elise with sports exhaust pops on overrun. My old man reckons the engine needs tuning but I guess it depends on the engine?

So in laymans terms, is it ok and why?

[NWTony]

I believe it's unburnt fuel getting to the exhaust and may well be a problem for your cat, if you still have one.

[MagicalTrevor]

NWTony said:

I believe it's unburnt fuel getting to the exhaust and may well be a problem for your cat, if you still have one.

Thanks Tony, I'll ask the chap who looks after my car to take a look.

Still sounds awesome when it pops mind

[ewand]

Isn't that one of the points of having the sports exhaust (depending on how much it does it/how loud it is)?

My S2 had a factory sports exhaust and used to burble and pop a bit on the overrun - sounded great!

[MagicalTrevor]

I thought so to, my Dad insists that it needs tuning. I suspect he's just jealous

[Moospeed]

Gotta love a nice pop on overrun, if it's accompanied with a spot of flame even better

[bordseye]

popping is just unburnt fuel exploding in the exhaust rather than the engine - fuel wasted and which gives you no power. If you like the noise, you might like the old trick of turning off the engine with the car in gear and going down hill, then turning the engine on again and getting a big backfire. Probably doesnt work with fuel injection, just with carbs.

technically, your dad is right

[aelord]

It is not a problem -it is a key feature of sport cars!

[John145]

Modern cars dump too much fuel to cool the cats hence popping - not a problem.

[BibsTLF]

John145 said:

Modern cars dump too much fuel to cool the cats hence popping - not a problem.

Erm,

"Any condition that causes abnormally high levels of unburned hydrocarbons—raw or partially burnt fuel—to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction."

[jondude]

Hole in exhaust?

[John145]

BibsTLF said:

Erm,

"Any condition that causes abnormally high levels of unburned hydrocarbons—raw or partially burnt fuel—to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction."

Wikipedia isn't always right.

[Hollywood Wheels]

God I miss my Elise! I used to drive it through the Limehouse Link, and watch the tunnel light up as it spat flames from the exhaust. It would pop and bang every time I lifted off the accelerator. I must admit, I never actually considered whether this was 'good' for the car, as I was too busy watching the cars in front slam on their brakes as they shat themselves because of the noise. Hope this helps the OP.......

[chieflief]

John145 said:

Wikipedia isn't always right.

WHAT?!?!?!?

[budgie smuggler]

John145 said:

Wikipedia isn't always right.

{CITATION NEEDED}

[Captain Muppet]

budgie smuggler said:

John145 said:

Wikipedia isn't always right.

{CITATION NEEDED}

Hang on, I'll just edit the wiki page and reference a book I know no one else will bother to check even exists.

[dern]

It's worth checking your exhaust for holes/leaks as was mentioned earlier.

[MagicalTrevor]

dern said:

It's worth checking your exhaust for holes/leaks as was mentioned earlier.

Thanks, will do. It doesn't sound like it's blowing under normal use though