I recently got the rally cat (which is awesome), but the exhaust smells a bit rich at idle like when I'm stopped at stoplights. How much is it safe to lean my map out, and what ranges should I do it for?

TIA,

 

what is the AFR your wideband claims?

If your fuel trims are out of range, it will run rich if the injectors are adding more fuel than the trims can handle, otherwise in closed loop the car will always seek out 14.7 and there is very little you can do to alter that (at the moment)

 

Is it stock injectors or what if it is then you shouldn't have to do anything closed loop should handle it

 

Thanks guys.

The car is completely stock, with just an eFlash. Injectors are stock and I don't have a wideband. But I know that it's running rich as the smell is pretty noticeable.

Is there anything that I can adjust to lean it out a bit? What should I look at?

 

As long as the fuel trims are in range, then its pretty much 14.7.. You can't really alter that, and you won't be running too rich..

If you smell "Rich" then either something is wrong, or your not running a cat, or something else.. But closed loop pretty much handles itself, so as long as the car is tuned and running properly, it will always target the same AFR which is 14.7 I don't "Smell anything rich" at that AFR, though it does smell different whether or not you have a catalytic converter.

 

Plus if you don't have a wideband, you have no way to tell if your running rich (besides looking at your fuel trims, if their -25 and don't change, then its probably running rich, but you cannot know for sure)

 

That's essentially what the rally cat is. Perforated test pipe with the cat on the outside. Basically a test pipe.

I started smelling it after I took off the cat and replaced it with the rally cat.

Is there's anything that I can log with EcuFlash that will tell me anything?

Btw, thanks for all the help.

 

Nope, well, not anything of alot of value, the front and rear O2 sensor voltages can give you some indication of whether or not its lean, as will the fuel trims if their out of range, but without a wideband its difficult to tell.

What your smelling is what you would typically smell without a cat..

 

Thank you.

I can accept that. If it can't be tweaked, no point in stressing over it.

 

FWIW, A 3 way cat takes three things out of your exhaust gas. If you put in a test pipe, things *should* smell different. If it is any consolation, a post cat O2 sensor generally shows a leaner reading than a pre cat O2 sensor at closed loop idle. So your nose appears to be in sync. No cat means hydrocarbon output soars, which you are interpretting as 'richer'.

Chances are very good that your car is running were it always has, stoichiometric. The only reason to really run here is emissions control (ie, cat efficiency), so it probably would be better if you could shift from lambda 1.0 to, say, 1.05 (close to best economy).

There is no simple ECU setting you can currently make to accomplish this (and, while I don't dispute MJ's assertion that this may change in the future, it seems like a fairly complex ECU code change to me). What you could potentially do is install a wideband controller and then use it to simulate the narrowband O2 sensor (front) that your ECU uses to find stoich now. The narrowband simulation can be shifted, essentially fooling the existing ECU to run leaner.

On the flip side, if an ECU employs 'learning code', you might have to alter your open-loop fuel maps as well, since the ECU would tend to run a little leaner WOT than before.

Good Luck,
-jjf

 

Sounds like I should leave it alone and let someone who knows what they're doing mess with it.

Thank you!