I live in a state that unfortunately requires emissions testing. Only the sniffer.
No visual.
I am running a halfbridge, with premixed E85. A Corvette air pump and a old cat I had laying around.
I took it in with all this hooked up and tried to lean it out the best I could.
It failed in most areas, but passed in a few.
Here is what I am thinking as my next steps because they have revoked my registration until I get it to pass.
-#1-Maybe my cat is bad? You can see through it when you put it up to the light, but when I had it on there, it got glowing red hot. I'm wondering if that burned it up?
-#2-Put some E98 in there WITHOUT premix? I'm wondering if the premix is causing it not to pass? Also wondering if it would hurt to run it just for a little while without premix.
Anybody have any ideas they could throw my way?
HELP!
Thanks!

 

numbers would help....

basically with a cat you do want the mixture to be about 14.7:1. if you're richer, HC and CO will come up. if you're leaner HC and CO go down, until the engine starts misfiring, and then they will be really high, while NOX will come up.

generally the NOX limit is high, and the HC limit is low...

i've found that timing has very little effect on HC and CO, but more timing = more NOX

the overlap the bridge adds is bad, its like taking an engine with a huge EGR valve and making it bigger, the BRAP BRAP is misfire because there is too much exhaust gas in the chamber. worst case i guess you block off the secondary ports...

i don't know what effect E85 has on emissions, i've googled it, but didn't come up with anything concrete.

you may also want to try using port air instead of running it to the cat. look in the FSM for that one

good luck! you should be able to get it to pass, actually, but its a bit of a balancing act

 

and be sure you retard the timing, don't run your advanced typical timing for e-testing. lean it out until it starts to want to stall then richen it up a tad. too lean will actually start to increase emissions again as if it was running rich.

 

How about negative spit? I heard the 8 runs negative split to help emissions.

 

try whatever you want but without a gas analyzer you might be working in the wrong direction just guessing at random things.

 

it does run negative split, but it goes away very fast with load and rpm, so during an E test @2800rpm its probably running normal timing

 

Got it to pass!
Put a cat on it, electric air pump from a Corvette, Filled it with E98 and tuned it to stoich.

 

congrats! the idle test is the hardest one.

oh and its a half bridge? did you do anything like block off the ports? or is it just 14.7+ air pump+cat?

 

Nope...didn't have to block off the ports. Now I don't have to worry about selling it!
Next project is a widebody.

 

so you're saying if i put the electric airpump and a cat on the P port, i'll be in the ball park? that's tempting!

 

Don't know about a PP, but as you can see, my halfbridge was way below the maximum on E85/98.

 

ya, i usually just run 120KPH down the freeway with a potato stuffed in the thermal reactor. then the sniffer only smells french fries and fools it. (premix can cook potatoes, its fun, but not delicious.)

 

that would have passed in california!