I get a fine layer of black soot on my rear bumber & surrounding areas.
I replaced the FPR because somone said it could be dumping too much fuel into the injectors and it is not getting burned efficiently, but it still happens. I will be replacing the Vacuum hoses with a LR kit soon to see if that is causing the problem. The car runs fine & idles smoothly but I get the feeling something's not quite right with the mixture.
Any suggestions ???

 

Check the voltage coming out of the AFM. If the spring-preload adjustment has been changed, it's possible the calibration curve is off. If the spring-preload is too loose, the flapper door would open more then any air-flow than stock. The computer would be fooled into thinking you're got more flow than actual and inject too much fuel.

So measure AFM voltage at a couple points:

- idle = ??
- 2000rpm/3rd-gear =
- 4000rpm/3rd-gear =
- 6000rpm/3rd-gear =

And compare to a car with known good AFM.

 

Bump