Took a look at my exhuast pipe yesterday and it looked black and sooty, as if the engine's running rich.
Isn't the ecu supposed to run the engine at optimum and give me a nice grey deposit (so to speak)?

What car you got?

If you drive like me you'll always have a sooty exhaust

1.8
How do you drive then ?

Mine's black and sooty as well - alway has been.


Mark

chances are it will run slightly rich as standard. In experiance with 2 stroke motors it is better to have them run slightly rich, as this keeps the engine slightly cooler and helps lubricate the hole process. So i guess the same applys 2 our engines.

Also dont forget that oil is under preasure behind our pistons, so unless your pistons rings are aboslutly perfect you are gonna get a little oil through there.

as long as your car is running fine then i wouldnt worry about it. if it starts to eat plugs and not run properly then its different, but until then dont worry.

Arty

[quote="wombleuk"]1.8
How do you drive then ?[/quote]


Too quickly lol ........ no Mazdas do tend to soot up more than most. Its normal

thanks Guys.

Can agree with all the above. Cleaned my 1.8's exhaust the other week (sad I know) and it is all ready getting a slight sooty deposite. My Xsara VTR's were the same. If it's any concelation I'm getting 32.5MPG at the mo so it definatly running fine.

42lts into 308 miles

[quote="Stuart McB"]Can agree with all the above. Cleaned my 1.8's exhaust the other week (sad I know) and it is all ready getting a slight sooty deposite. My Xsara VTR's were the same. If it's any concelation I'm getting 32.5MPG at the mo so it definatly running fine.

42lts into 308 miles[/quote]

[-o< Ah I thought my car was exceptionally bad on petrol - I get about 320 miles to a tank, glad to see mines not running badly after all!

Nah ain't run her till the light comes on just to when the needle is pinting at empty I thought that was good for the old girl 32.5 mpg

You guys are doing well - I get about 400 km's to 42 litres - that's only about 260 miles ...

Could be your lambda sensor's on the way out.

It's the bit that senses how your engine is buring and tells the ECU to adjust the mixture to correct any differences.

An OE version is about £90

The sooty deposit is carbon, and is completely natural from the combustion process.

Petrol is basically a soup of chemicals, but the main content is hydrocarbons from oil (hydrogen and carbon mixed) so when you burn petrol you are oxidising the hydrogen which gives you carbon (soot) and oxidised hydrogen, otherwise known as water.

If your car is running rich then the likely sign will be thick brown smoke from the exhaust( black if diesel), if it's burning oil it's blue smoke, and water in the fue/air mixture is white.

Hope this helps - tomorrows lesson if anyone is interested, why exhaust rot so badly.

[quote="Smotter"]You guys are doing well - I get about 400 km's to 42 litres - that's only about 260 miles ...[/quote]

I get that out of my V6 andrew