Spyerx

Any pointers? Car has passed every year w/o issue. stock cat, chip, etc. Motor is stock, plugs new, wires new, cap rotor new, seems to run OK...

ideas before i bring to my tech?

Last time almost all the measures are very very close except low CO, which time was .38

Techno Duck

High CO along with the higher than normal HC indicates running rich, what is the age of the O2 sensor? Also was the car fully warmed up prior to doing the test? The DME may still have been commanding a rich mixture if not up to temp.

Spyerx

Car was very hot did freeway run and went right to smog place.

O2 sensor not sure age. Anything else cause this situation?

Does this ecu have any memory that needs to be cleared?
I have a Steve Wong chip, will this run leaner?

Lahainabry

I am not an expert on this but had the similar issue with an older 450SL. Mine was the 02 sensor.
However, it being bad ruined the catalytic converter. I had to do 2 sensors and the converter. Passes easy now.

Spyerx

my hc are low so hope cat is good

esc911

I've read on a few threads on pelican about the pin 10 (brown) wire needing to be connected for smog with the SW chip. Not sure if it applies to CO or NO.

Spyerx

I have stock chip in the car and the pin 10'is unplugged (as delivered for Cali)

oldskewel

Your HC are low enough to pass, but not as low as they could or should be.

For reference, here is my last smog at the 15 mph test (for my '85, so the specs are a little different):
mileage 133858
speed 15 mph
RPM 1494
CO2 14.5
O2 0.3
HC(PPM) MAX 97
HC(PPM) AVE 33
HC(PPM) MEAS 15
CO(%) MAX 0.59
CO(%) AVE 0.22
CO(%) MEAS 0.07
NO(PPM) MAX 804
NO(PPM) AVE 373
NO(PPM) MEAS 351

Your 91 HC is almost at the 97 max for my '85.

If it were me, I'd replace the O2 sensor, just in case it helps.

Spyerx

Got a hand from an awesome local Pelican member, we hooked up an AFR meter and found it running really rich. So, swapped in a spare meter and bingo, perfect afr, better idle, more power, less stinky exhaust. I'm swapping the O2 sensor now and will make another smog attempt after running the car a bit to get it nice and hot. In meantime will drill out the adjuster screw on my meter so we can get it adjusted properly.

Fingers crossed!!!

C4inLA

Spyerx,

Could you explain your last references to meters and drilling out ??? Hooked up a meter, swapped a meter? Sorry. Trying to education myself on A/F mixture in our cars, etc...

Thx..

BtW, sent your friend a note weeks ago and didn't hear back... I suspect, case of another one man show in demand. All good, I doubt he has time to be picking apart gearboxes...

Spyerx

This thread I posted on pelican has more details

http://forums.pelicanparts.com/porsc...est-ideas.html

C4inLA

Thanks, all caught up .... Community came through for you, awesome....

Spyerx

Yeah let's see if it passes tomorrow. I'm optimistic!

Spyerx

And we have victory! See the pelican thread for more details, but essentially adjusting the AFR while under idle fixed it along with a new O2 sensor. Car was running super rich.

Techno Duck

Always a relief to get that out of the way. I have to retest before March of next year, maybe earlier if i decide to sell. The car runs great but always makes me nervous!