clsund1

Hi everyone,

I have an 04 996TT and I was told that I'm running rich (based on the mechanic's smelling the exhaust). What would be possible causes for that to happen? I have stock intake and aftermarket exhaust. I don't have any flashes (as far as I know).

Any help or suggestions would be appreciated. Thanks.

Third-Reef

The mechanic is poor is my best guess. Actually i think this is normal, especially on startup. My 02 pops and growls on startup and makes my eyes water if i am back there. Give it a few minutes and it smooths out and starts smelling normal. The DME runs it real rich at first to heat up the cats. I get 20 to 22 mpg on the highway so mine can't be too rich.

RngTrtl

log the air fuel ratio from the wide band 02 sensors with one of the cheap OBDII bluetooth adaptors to your phone and see what the scoop is. Trying to rely on a smell test for rich or leans conditions aint gonna cut it.

clsund1

Ok, thanks for the input. This is what happens when you're new to the car I guess.

996tnz

Any chance yours has an aftermarket tune? They normally run richer to prevent knock - ie compensate for advanced timing and higher charge pressures.

Even then, if the back end of your car isn't rapidly getting very black from soot (hard to tell if she's dark of course) it's probably just fine. Mine gets dirty pretty quick but she's tuned, and the insides of her exhaust tips still turn white after working hard on track so not running over rich. Plus her AFR logs are fine.

Trust you're enjoying your beast.

clsund1

I am enjoying it, every time I drive (which is daily) and it truly is a beast.

It doesn't have a tune as far as I know. May need to dig deeper on that issue. My exhaust does have deep black soot on the tips, which partially is making me think it is running rich.

T10Chris

Does your aftermarket exhaust retain cats or delete? If it deletes cats, you will always have the fuel smell...

clsund1

I'm in California so it has cats.

996tnz

OK. It is normal to have some black soot build up inside the pipes with normal road driving. Unless you're repeatedly running it to redline every few seconds for at least 5 minutes at a stretch (ie pushing it on track or extended ultratight twisties), in which case they'll likely turn white. Then go black again over a few days of normal driving.

But if you want to be sure she's in the normal range, either log your AFR (air fuel ratio) have a tuning place do readings via the OBD port in the footwell or stick sensors up your pipes.