Modify tables to pass emissions test

[kuprito]

Hi,

I have to pass the emissions test soon, and I don't want to reinstall my catted downpipe. I know people that have passed the test with no cat without modifying tables on some cars. I want to be absolutely confident that my car will pass this test making all the changes relative to emissions on the tables.

I know they measure this 3 factors.

CO at idle (I think it should be 0)
CO at constant 3000rpm, almost nothing of load (I think the top mark here is 0.3)
Lambda factor (It should be 1 with +-0.03 error)

I think the most important tables are:

-Power enrichment (not needed to touch anything cause I have 1 til the 80% column)
-Variable camshaft ?¿
-Spark advance

Does anybody know how to modify the last two tables to have the lower values possible? And any more tables to modify?

And very important, go there with hot car.

[CarsonTech]

Seeing how a gasoline combustion engine produces carbon monoxide and one of the CATs functions is to oxidize carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2, I am not sure this can be done in a CO test unless you have a CAT.

Would be interesting to hear more responses about this. Personally. I am not sure this can be done without a CAT. Then again, I never lived in a state where there was testing of any kind.

[rnjmur]

The only way to make the CO levels lower is to run the car leaner. Without a CAT I don't think you will get the CO levels low enough to pass a sniffer test.

I doubt changing the cam and spark tables are going to effectively lower CO emissions enough either. If you change the cams to change light load air you might be able to lower the CO emissions a bit, but since it sounds like you don't really have a good understanding of what making those changes are going to do I would HIGHLY recommend you not start screwing with the cam tables, or the spark tables for that matter. The only real way to pass the sniffer is going to be putting the catted downpipe back on.

[kuprito]

Well, I'll say that in other words... how can I get the lower CO possible?

[Pandion]

Honestly unless you have an Aftermarket cam or pistons or messed with your MAF tables at idle to run really rich I would think you should pass no problem. I have a small block 350 with a mild cam and a bunch of other go fast goodies that passes at cruse and only has a hi HC at idle from the lumpy cam. Thats with no cat and comparing it to new car standards. Also on a 750cfm Demon carb and double hump heads.

Hmmm... But then again. Do they do a visual inspection where your at? That could be an issue when they see no cat.

[kuprito]

.

Hmmm... But then again. Do they do a visual inspection where your at? That could be an issue when they see no cat.

Nope!

If the car passes the emissions test, that's all, no visual inspection.

Thanks for your answer!