Heya, I'm trying to get my single turbo FD through emissions (dyno roller type test).

I've already got about 12% denatured alcohol in the tank with no premix... I also run the stock main cat and a 1997 Vette airpump rigged up to pump air in there. It's still a little over the limits on hydrocarbons and carbon monoxide.

I think if I tune it with my wideband for a very lean AFR under the parts of the fuel map that the test uses (no boost, under 3500 rpm), I can make it pass. The question is... how lean can I go?

Right now I'm around 14.0 AFR, but maybe I should go leaner... 15.0 perhaps?

Brian

 

OK I took advantage of the weather today and tuned for 15:1 AFR in P1-P11 and N1-N10 on my PowerFC/Datalogit/Techedge Wideband setup. The car drives fine so I guess it's cool. The rest of my map is still set up for my "safe AFRs" so if somehow I go into those areas, I am OK.

Any other tips for getting your emissions down? Any tricks on ignition timing?

Maybe I need to get another vette airpump and have TWO of them pumping air into the cat

Brian

 

When you say denatured alcohol...is that rubbing alcohol?

I gotta do mine this week

 

I'm probably gonna lower the **** out of my car so it won't fit on the dyno

 

I buy a gallon of denatured alcohol from Sherwin-Williams (paint store) or Home Depot. I put that into a 1/4 tank of 93 octane. Don't run premix for the test! It makes your HC numbers higher I think.

Rubbing alcohol is isopropyl alcohol if I remember right (it's late!), and that will work I think, but denatured alcohol is typically over 85% ethanol which is preferred. The remaining 15% is usually methanol, methyl ethyl ketone (I think) and a few % water. Water is unavoidable when dealing with the stuff, but since the alcohol attracts the water, it pulls it through the fuel system and it does not accumulate in your tank.

Brian

 

Lowering the car sounds good, but you would ahve to be pretty low. My fender lip height is 25 1/4 inches and they still put mine on there the last 3 times.

I wonder if anyone knows a test station where a little money can fix this issue....

Brian

 

14.0 is pretty rich! I ran mine 14.7:1 on the smog dyno (CA) with a new (cheap) high flow cat, and passed. I'd probably try 15:1 if I had to do it again. I had straight 91 gas with premix in the car. Only things I did were back the ignition timing off 5* across the board, new plugs, and a 15* split.

Worked like a charm Apparently as you lean it out, NOx emissions increase, so you have to watch that (I didn't have a problem though).

-Manolis

 

For what it's worth, my PFC would run AFRs around 17 at idle/light throttle.

If you were serious about trying a second air pump I have one sitting here if you need it.

 

can someone explain how putting alcohol in your tank helps to pass emissions. and what harmful effects it has on your car.

 

with a cat you want to run 14.7:1 all the time, too lean and the cat will overheat, and too rich the cat wont burn everything off. the problem is the rotary wont run 14.7:1 at idle speeds, which is why they have the air pump. the other problem with being too lean is the it can misfire thus raising the levels of hc, usually with a cat you need to be a little rich.

mike

 

I passed emissions today running high 14s to low 15s in the area of the map where the test is run.

Just FYI if someone else stumbles upon this.

Brian