OK....


So I'm trying to pass smog, and I passed the idle test perfectly, and on the HC numbers at the 2000+ RPM range I passed as well, but I failed the CO.


Anyway, the car had an audible backfire, a slight pop sound every few seconds. This obviously means the engine is running rich in this RPM range and the extra fuel is causing it to pop.


Here is the thing:

I leaned out the PIM % in the 2000 RPM range at one point all the way down to 50% fuel. IT STILL had the backfire noise and still had too high of a CO level.


Anyone have ideas what I can change to fix this? I'm so close to passing smog with no emissions other than the air pump and cat w/ the power FC. Any help would be appreciated.

 

Explain how they test for emmissions there: idle, dyno, gears and rpms used, etc.

 

It is just an idle test (non dyno) where they rev it in neutral to 2500 RPMs or so and hold it in that range. I've found that with the power FC base mod map that it has a small backfire in this range or pretty much any RPM above 2000 when you hold it constant. It's a slightly audible popping noise from the exhaust, not a violent backfire like under WOT with no cat, but you can hear it popping and I did fail the CO portion of the load test. I passed and and the HC section of the load test with flying colors.


Thanks