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exhaust backfire????

37K views 10 replies 10 participants last post by  binda4me 
#1 ·
is the mild backfire in the exhaust of the mini cooper s normal??? when you rev up to 3500rpms and then release, i heard some mild backfire... is this normal??? my mini is just 300km.... :confused: :confused: :confused: :confused:
 
#3 ·
I hear it all the time...I love it though. :D I'm not sure if it's great for the engine as it would seem to imply that the engine runs pretty rich most of the time...an idea which seems to be further supported by the pounds of black soot that collect on the tail pipes?
 
#4 ·
First lets us be clear here. "Backfire" literally means that the fire from the combustion chamber is coming back thru the intake. If this is what you have, you have a problem and it needs attention NOW!

If you are hearing "popping" from the exhaust then this is, can I say, "normal" after a rev-up and quick release. GTmini is correct in that the MINIs do run rich and the unburned gasoline vapors are ignited in the cat, making popping sounds. Too much of this and you might end up with a burst cat.

With all of the fancy computers and fuel injection why do we still have black tail pipes? I had cleaner tail pipes on my 1972 Fiat 124 sedan with a single 2 barrel Weber carb. Always a very nice light gray, the plugs also. No stinking computer, no ECU, no fuel injection. Why, 30 years later, is the exhaust dirtier than before? So much for "clean air"

Rant over. Sorry.

Bilbo storms off.
 
#5 ·
Bilbo Baggins said:
snip.....

With all of the fancy computers and fuel injection why do we still have black tail pipes? I had cleaner tail pipes on my 1972 Fiat 124 sedan with a single 2 barrel Weber carb. Always a very nice light gray, the plugs also. No stinking computer, no ECU, no fuel injection. Why, 30 years later, is the exhaust dirtier than before? So much for "clean air"

Rant over. Sorry.

Bilbo storms off.
Yea really!!
Storm away. It bugs me too.
 
#6 ·
Well it is not a secret that the MINI does run rich. Someone did a dyno run with an air/fuel mix reading and found that once you go over 4k rpm, the air/fuel goes from around 11:1 to 5 or 6:1. That is very (almost like race cars) rich! That is definitely the culprit for black deposits on the tailpipe but the popping sound might be due to the fact that (I think) the MINI continues injecting fuel into the engine even when off the throttle. Other cars such as BMW cut the fuel way back when off throttle, and hence, don't pop.

My other car (a Honda Insight) runs as lean as 22:1 and actually has to switch out of this "lean burn" mode on the fly in order to burn out the cat which can only collect the bad stuff when running so lean! I'll never see black stuff on that tailpipe. The Insight also completely cuts fuel when off the gas and above idle speed.
 
#8 ·
kapps said:
My other car (a Honda Insight) runs as lean as 22:1 and actually has to switch out of this "lean burn" mode on the fly in order to burn out the cat which can only collect the bad stuff when running so lean! I'll never see black stuff on that tailpipe. The Insight also completely cuts fuel when off the gas and above idle speed.
At night in my other car I can see the reflection of flames in the windscreen coming out the side exhaust when it pops. It runs exceedingly rich. Maybe a passenger could roast marshmallows.
 
#9 ·
Ive noticed this too on my new S. Just a whisker over 900kms and the pop/burble sound is pure gold! :D

I love it. Always assumed it was just part of the car's personality.
 
#11 ·
Back Fire

We have a 2013 Mini Coupe and the back fire problems started at about &,000- miles.
When I complained to the S.F.service shop they said I should only use Chevron, Union 76, or Shell gas and add Techrolene every 1000 miles as the problem was due to the ethanol in the cheaper brands. So I changed and the problem still exists.
I'm also concerned about damaging the cat and it suggests a too rich setting lowering gas mileage.::frown::
 
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