Suggestions?

I have an SAFC which is not being utilized at the moment, do i need to lean out or richen the mix at idle?? how much?


Here are the stats:


RPM C02(%) 02(%) HC(PPM) C0 (%)
Meas Meas Meas max ave Meas max ave Meas

688 14.3 0.6 100 17 203 1.00 0.0 .33
2725 14.4 0.5 130 12 38 1.00 0.10 .24


FAIL


Mods:

CAI
4-1 Headers
1 Cat
Catback

-Gagan

 

Cliff notes: 103 over on HC(PPM) at idle... how to fix?

 

pm'd

 

Thanks. But I'd like to just try to fix the issue. It will pass.

 

Is that a new cat Gagan?

Also, Oxygen Sensor may be bad.

 

Throw the second cat back in, and lean it out at idle. Normally the "trade off" is that if you lean it out the HC will go down but NOX will go up. Fortunately for you (and all other Subaru owners) is that the idle/2500 test does NOT measure NOX (the dyno roller test does measure it). ECU tweaking can work some miracles in that case

FWIW, this Saturday I smogged my Impala with the stock motor and stock cats (along with "tweaked" ECU) on the dyno rollers. Tailpipe numbers were 9 PPM on HC at both 15 MPH and 25 MPH. Last time I did idle/2500 on it with stock cats (back in 1998) it was under 10 PPM for both RPMs (I think 7 at idle and 2 at 2500?). Those GM cats are pretty good, so good in fact that a buddy of mine up in Massachusetts has failed their idle/2500 test for being TOO clean (as in, car blew so clean thru the tailpipe that the state computer just assumed things were broken with the smog machine ).

When I smogged the (stock) WRX in March before selling it, it was something like 17 PPM at idle...yeah, the "ULEV" was dirtier in PPM than my "big evil V8 musclecar"

 

nope, all good there

Ok. I'm going to play with the SFAC at idle to see if i can raise the EGTs a few hundred degrees and then go test it again.

I need to drop 103 HCs, I wonder how much higher in EGT i need to go.

-Gagan

 

u need to check CO for mixture problems.
HC goes up for both rich and lean conditions
CO high = rich

 

to acheive a target HC, I need to literally put my afr at 14.7?

Or am I pretty much going to have to put my oem header/cats back on (PITA)

-Gagan

 

at about -7% fuel at idle the car starts to stumble slightly. EGTs don't go up really or don't show going up in any significant amount.

raising the fuel to about +10% looks to make the car stumble and die.

Looks like I know what I'll be doing wednesday night

 

EGT will not really change appreciably at idle, so don't use it as a judge.

HC is, simply put, incompletely burned fuel. If you're lean, HC will NOT be high but you will have NOX shoot thru the roof in a hurry.

Try leaning it out -5% at idle and go retest (assuming you have "free" retest). If that doesn't do it, then do the cat swap.

 

call Adam @ LIC or just go to the shop because not only can he figure it out quick but there is a smog guy in the same alley way!

 

did you try heating up the cat? I've heard of this working a couple times, car won't pass, they heat up the cat and it passes.

 

+1!!!

Otherwise swing by my house some night this week and we can put you back to stock.

 

I'm going to try going -5% and see what happens. If it works, great, if not, then I'll just have to swap back to stock Wednesday.

-Gagan