I'm the new proud owner of a '06 Evo IX but I'm having issues passing smog

This car was originally very well tuned by a reputable tuner using ECU Flash...things that have changed since then are the FP cams and me putting back the stock cat and exhaust

I figured that I could basically zero out the fuel trims, toss the stock cat on and that I would be ok passing smog. I adjusted the MAF calibration to get my short-term Fuel Trims to 0-2% at idle and 0-3% at 2500

I have a smog guy that will overlook everything else as long as the car passes tailpipe. These were my results:

Idle (1000rpm)
HC: 264 ppm
CO: 0.01%
CO2: 15.1%
O2: 0.0%
NOX: 0

2500 RPM
HC: 82 ppm
CO: 0.34%
CO2: 14.9%
O2: 0.0%
NOX: 0

Relevant Mods: FP 4R cams, HKS filter, Injen Intake, Ebay FMIC, 3" Downpipe, MBC set at stock boost, stock cat and catback exhaust

So the only thing that is out of wack is the HC's at idle. I didnt realize till I got back that my timing at idle was set to 11-12 degrees

Would this advanced timing cause my high HC's?

 

yes, the timing at idle can cause the HC levels to rise and cause the tech to fail the smog test.

 

The thing I don't understand is how my fuel trims are so close to zero if I'm running so rich at idle

 

Does timing (in this case, about 6-7 degrees advanced) make that drastic a difference? Or do I have some other issue as well?

 

You aren't running rich, you're running 14.7 AFR.

 

Right...this is what I was thinking. So why are my HC's at idle high?

 

I don't even know what HC stands for, we don't have smog tests here. It very well could have something to do with the added timing at idle though.

 

HC stands for hydrocarbons...unburnt fuel

 

It's called lumpy cam syndrome, you're running a ton of overlap with a modded cam at idle, thus your HC is high. HC's are mostly from UNBURNED fuel vapors. Notice how they decrease with RPM, that's because they are designed for top end power at ALL cost... including low end and emissions. A TWC is designed for all emissions and honestly isn't great at dealing with HCs for long... in fact overdoing it will kill a cat pretty quickly in most cases. Newer cars will actually go into complete fuel cut during a misfire at anything over 25% throttle for that reason (Toyota 2GR for example).
Your ignition timing has little to nothing to do with it, if you picture the unburned mixture exiting the exhaust valve you'll realize the issue you're dealing with. You need a compressed charge to ignite so you could set the advance anywhere and it won't effect what's already in the tailpipe. Lowering the trim effects the entire charge, but 30% is exiting the tailpipe so you're pretty much SOL.
While I'm smog certified I never use it here in FL so my experience in the numbers is low, what do you need at idle and at 2500 rpms to pass?
I've been scratching my head to figure out a way to get around it without swapping the cams back, but I'm at a loss right now... post up the passing numbers and I'll marinate in the meantime.

 

it very well could. this is IGNITION timing......what about CAM timing?? do you have adjustable cams?? also, the ignition timing you see is only 'target' timing. meaning-this is what you have commanded the ECU to TRY to achieve. it is pretty close most of the time...but there are still variables.

as stated by the post above, the HCs could be affected by the fuel trims....even though they are close to zero, doesnt mean they are meant for smog...only power.

you said you put the stock cat back on..was the car resting for any amount of time before the smog>>?? meaning that the Cat was allowed to cool a bit before it was 'lit off' again? did the smog tech allow the car to run up to 2000 rpm for about 3 min prior to taking a reading again?? sometimes the cat needs to be 'lit off' in order to 'help' the smog. mine does...

there has to be a 'work around' as mentioned by TURN9. he has some great info there.

 

Thanks for this...very informative. I believe the limits are 100 ppm @ idle and 130 ppm @ 2500 rpm....so I'm ok at 2500 but really high at idle

 

No, my cams are not adjustable....atleast through cam gears.....I can, however, tweak the MIVEC settings for adjustments on the intake cam though


This is a good point...I'm gonna put a timing light to it today and see what the true timing is


I mad two back-to-back WOT runs to the top of 2nd and then held the RPMs at around 3K for like 5 mins while the tech was getting the test ready....so the cat should have been warm

 

This. The overlap in the cam is causing the high HC. Throwing stock cams in is the easiest way to get though smog.

 

P.O. BOX in another county? State? Be done with the smog testing all together...just a thought. Another more feasible thought would be to run e85, I believe that has extremely low HC output, correct? I am glad I don't have to worry about that, for now anyway. Good luck, I hope you don't have to switch out the cams to pass, that would suck.

 

Definitely not goin through the hassle of putting the stock cams back in...if it comes down to that, I'll just get it "smogged" someplace else...but that will cost me a good deal extra

I saw several threads with people passing California smog with cams so I think it's doable...particularly since the FP 4R cams are not very aggressive