Hydrocarbons: Standards = 0.80 GPM. Reading = 1.42 GPM FAIL

CO: Standard: 15.00 GPM, Readign = 4.90 GPM PASS

NOx: Standard: 2.50 GPM, Reading = 2.33 GPM PASS (barely...)


Adjusted TPS

Reset TPS
Initial reading:
Idle: .67v
WFO: 4.61v

reference = .50v @ I, 4.5v @ WFO

New reading:
Idle: .49v
WFO: 4.43v


I also ran the tank vent straight to the IM. Before i had just let it dump through the fender (eliminated evap emissions). State mechanic said HC's can be evaporative emissions as well as unburnt fuel, so I was hoping this would drop it.

Drove the car hard to get the cat as hot as possible. I also went to a different testing station where there wasn't a line, so I got tested with the cat pretty darn hot.

My second test:

HC: 1.48 (up .06)
CO: 4.50 (down .40)
NOx: 1.42 (down .91)

Now I just had the car tuned. My setup is:

D16z6
10.3:1 compression
Ported head
Oversized valves
Stock valvetrain
dc header
Portmatched and polished z6 IM
~100 mi on engine
Running obd1 in a 91 Civic STD hatch off a p72 chipped and tuned, AFR's are all in the right spot thoughout driving range

I have the option of titling it in a different county to avoid emissions altogether and might just do that.

What could be causing the high hydrocarbons if my AFR's are okay, and the cat's obviously doing it's job?

 

Bump

 

HC is mainly caused by ignition problems, i would check the secondary ignition plugs, wires, cap and rotor. Based on your CO level i would say your car is running on the lean side on the dyno, very lean air fuel mixture is not ignitable even by the best ignition system, a lean misfire also causes unburned fuel to escape which can explain the high HC reading. I would add a little more fuel throughout part throttle cells and do a retest.

 

I had the same problem and saw that i had a hole in my charcoal canister..have not taken it back yet bc i found this out after i had pulled the engine...

 

Thanks for the responses, haven't checked back on this thread for a while. I went ahead and stripped the car back down and it's in my garage awaiting paint.

I did have some issues with injector wiring that I sorted out before emissions testing, but weren't there while tuning.

There were a few other bugs that I adjusted to be correct, but all after the tune.

I eliminated my charcoal canister and routed my tank vent directly into my IM.

After I'm done painting it, I'm going to have the tuner come back over and throw the wideband on just for another check, see if everything's still where it should be/ see if anything's changed since the initial tune.

Worse comes to worse if I fail the third test I can register it out of state in a county that doesn't require emissions testing.

 

check the cat with a pyrometer it should have a 200 - 300 degree difference. also eck map sensor, spark plugs, oxygen sensor , wires cap rotor. etc

 

evap also has nothing to do with hydrocarbons coming out of the tailpipe. all evap does is vent fuel vapors from the gas tank into the engine so they can be burned up. unburned fuel = damage to the oZone

 

if your car is obd2, unplug and injector. it'll read less fuel. that's worked before.

if it's obd2, it'll code up.