Black soot !!!

[tom1]

This is probably a stupid question, but i have started to get some black soot type deposits on the back of my bumper from the exhaust, is it a sign of running too rich or could it be something else?

Cheers
Tom

[dummi]

is your CAT ok?

[alastairg]

I have always had this. When Mihnea custom remapped my car we had a long chat and the OEM map runs very rich to allow for poor fuel that some owners would have used. However any boost leak will cause richer running. I recently changed the MAF to TURBO air hose with an increase of 5mpg !!!! As thats all I changed I suspect I have run with a small boost leak for a long time. Big boost leaks cause significant performance drops & black smoke as the ECU cannot adapt to them. Small ones I suspect the car copes with & chucks in extra fuel.

[tom1]

How would i know if the cat has gone?

According to the trip i average around 18-19 mpg around town which is what i manily do, and around 24mpg on a run. There doesnt seem to be any loss of power to (still pulls like <beep>:))

[Lloyd]

As A said above. Soot means over fuelling, it's basically un-burnt fuel exiting the pipe. Look for an air leak. Perhaps change Lambda probe for a new one?

Can't see how it may be the cat's although happy to be corrected.

[tom1]

Looks like i should maybe check for leaks then.

[dummi]

don't worry I had been reading about CAT function earlier today, still at the front of my mind, it is more likely over fueling, especially since you still have power

[alastairg]

RS2 cats are wire mesh. IMHO they do not fail like ceramic cats

[AlWyn]

Tom give me a call if you want to try my `spare` probe CheeRS Al

[tom1]

I might do that Al...thanks:)

[alastairg]

I suggest you get the car checked for fault codes which may point you in the right direction

[tom1]

I think what i will do first is fill up with v-power as the last few fuel top ups have been with esso 97 as the shell garage is a bit of a distance and i have been lazy:(