I'd like to get a bit of info on how I can lower my emissions readings for an upcoming sniffer emissions test I need to get.
I have passed on all my other tests but I am always right at the limit on HC so I want to try and do some quick editting useing HP Tuners to try to help my numbers but I'm not really sure what will help.
My car is basically a bolt on car, stock cam and heads but runs rich ever since the exhaust was upgraded. I think that part of my HC problem may be that I have to do emisisons testing soon after I take the car out of storage. I always try to burn a couple tanks of fuel to get out all the fuel additive and I also stick with 87 octane rather than 91 or 94.
My first thought was to advance the timing, my thinking is that that would allow for a more complete burn of the fuel???????
Can anyone, maybe someone with some experience with this, give me an recommendations?

 

I dont like this idea, but you can make your car leaner, and lower your idle.

More importantly make sure your car CATs are HOT.

I failed once because my cats were not warmed up. I drive the car for a half hour, then returned to the shop.

 

+1. My car has one cat and it is takes alot of time to get it hot. Just rev it up so long that you can smell rotten eggs = cat is hot enough. By doing this my HC emissions lowered from 130 ppm to 44 ppm at idle and from 90+ to 5 ppm at 2250 rpm And that's with LT's, Comp 216/220 114 LSA cam and other bolt ons, untuned and not running lean.

 

I thought this might be helpful :




Cheers -
Rob (Bad30th)

 

Give it a run on the highway for half an hour to warm up that CAT. In Oregon I had to do the sniff test years ago with a carb. I would drive through, fail, go out raise the hood, adjust the carb, drive through, fail, etc. If I remember right, too rich would be high O2, too lean high HC.