2001 F-body Emissions Test

[joecar]

I went today for my 1st CA smog test on this car...

Results:

HC @ 15 MPH (1271 RPM): 2 ppm (allowed 50 ppm) -> pass
HC @ 25 MPH (1178 RPM): 1 ppm (allowed 34 ppm) -> pass

CO @ 15 MPH (1271 RPM): 0.03 % (allowed 0.48 %) -> pass
CO @ 25 MPH (1178 RPM): 0.02 % (allowed 0.45 %) -> pass

NO @ 15 MPH (1271 RPM): 679 ppm (allowed 414 ppm) -> fail
NO @ 25 MPH (1178 RPM): 464 ppm (allowed 701 ppm) -> pass

Please, any ideas...?

[cme265]

no(x)..... high combustion chamber temps....timing? lack of EGR.....high octane fuel?....the failure of high NOX on an e-test is the result of high combustion chamber temps.....i assume CA does the same IM240 test that colorado does?

[joecar]

G'day cme265,

2001 F-body came without EGR.

Using stock timing, minus a little at peak torque.
Using 91 octane fuel.

Using 180*F thermostat;
Fan Low On = 208*F
Fan Low Off = 200*F
Fan High On = 218*F
Fan High Off = 208*f
Should I set the turn on temps lower...?

Should I run a little richer (looks like I have room for this since HC/CO are very low), as this would lower combustion chamber temps...?

Yes, I do believe it is the same IM240 test.

Thanks,
Joe

[cme265]

well, i'm just thinking out loud, if you're running open loop, i would think if you richen up the mixture at that point it should help on the nox, just don't go to far as co will go up, give it a try, what's the worst that can happen, fail again?

[joecar]

I'm running closed loop, my car is all back to stock.

The test seemed to me to be light/medium load at 15 MPH (car seemed to be holding 2nd gear), so the PCM would have been in closed loop, I imagine.

If it's in closed loop, then I would have thought the AFR was in the right range for the cat efficiency for NO and HC/CO.

When I log on the street, I see around 0-2% LTFT, and HO2Sx1 voltages appear to be switching (altho not quite as high/low as I would like).

I'll change my front O2 sensors and try again (what's the worst that can happen...?)...

Thanks,
Joe

[cme265]

here in colorado we don't get the detailed report, just overall pass/fail so this is new territory for me, i'll see if i can bounce this off of some friends at work and get a collection of ideas, but either way post it up when it passes, curious to see what you had to do without an egr valve.....

[cme265]

don't know if this applies to 01 f bodies, but about 9 months ago i got a letter from gm stating the converters on my 02 f body were going to be covered for 10 years/100k miles, might be worth checking out?

[v8vegaman]

Could it be as simple as a thermostat change? Are you running a lower temp? It's probably a dumb answer but old school is still in effect regardless of year, engines are engines.

[joecar]

don't know if this applies to 01 f bodies, but about 9 months ago i got a letter from gm stating the converters on my 02 f body were going to be covered for 10 years/100k miles, might be worth checking out?

OK, I'll check this out.

[joecar]

Could it be as simple as a thermostat change? Are you running a lower temp? It's probably a dumb answer but old school is still in effect regardless of year, engines are engines.

I have a 180*F TS, but good thought.