HC levels for Emissions, uh oh Options

[Tigawoods]

well i failed my emissions test
the HC level had surpassed the legal limit
725is the limit and i ran 925

there are a number of things it could be but i beleive the main thing could be the SAFCII
which changed the air/fuel ratio
any idea's or opinions?

[hurley97]

Wouldn't excessive hydrocarbons mean you're running rich? Maybe my logic is wrong but I know hydrocarbon emissions is fuel that hasn't been completely burned. So if you had too much fuel going in and there isn't enough spark to burn it all it leads to unburned gas out the back, thus high HC levels, yes?

[Bitter]

could just be a weak cat....but try new plugs, wires, cap, and rotor first to see if your HC levels drop. which part of the test did you fail in? overall or just part of the drive cycle? was the CO also high? if the CO was almost at failing levels then i'd strongly suspect you simply have a worn out cat converter.

also was the engine good and hot for the test? try to go when you do not need to sit in line for more than 5-10 minutes and drive the engine hard prior to getting there. a good hot cat might pass just barely.

[Batman722]

You have a header that replaced your primary cat.
You will always have a problem with emissions because you're running too tich all the time.

What sort of "tuning" have you done with the safc ?
Do you have a wideband ?
Changed your 02 sensor lately ?

[lagos]

You have a header that replaced your primary cat.
You will always have a problem with emissions because you're running too tich all the time.

What sort of "tuning" have you done with the safc ?
Do you have a wideband ?
Changed your 02 sensor lately ?

He has a "guess tune" that I did for him based on Mannys old dynos. Basically slowly taking out up to 10% through the rpm range.
I will help him do it right if he ever visits a dyno.

The header is the cause for the emissions problem. You Need to install the stock one, or get another cat.
You could also try to take out some fuel from the low throttle map in the 1-3k rpm range (just for the test) to see if that helps bring the numbers down.

This post has been edited by lagos: Jul 3, 2008 - 11:21 PM

[Bitter]

haha, i suppose its helpful if people would post up what mods they have when posting a problem. the other forum i'm on has a template for problem report threads....and a separate section for them.

you might try replacing the main cat with a larger longer model designed for a V8 engine, like a ford truck. it'll come in a larger inlet/outlet diameter and should have enough catylyst to clean up the exhaust without the 2nd cat in place.

adding a 2nd cat downstream probably wouldnt work out since it may not reach temperature, also how cats function, there may not be enough stuff left in the exhaust for the reaction to occur.

[Tigawoods]

the first thing i am going to try is to lean out the a/f mixture, then if that doesnt work i will have to look into the cat situation

here are my other numbers

COppm's
limit - 1.10
me - .70

NOppm's
limit - 3600
me - 1797

thats why i am going for the a/f first lol


thanks guys for all your help
i will take it in early next week to re-test at a different place that will let me sit-in and tune the safc

[Toyotacelicafan1]

I know this sound silly and old school why not run a five gas on your car see what you get for reading if there high hc2 then you know the cat is working right. I know at most work place it in the corner buliding dust but hey it works for me many times solve problem and not playing throw parts darts at a car. IF it HC then check it out and see if your getting any noxs readings I mean little is good and that would mean the egr is working good. HC is not good like the others said do a tune up on it if you have not already done so.