I'M SO P.O'd! CA. SMOG!

Moke81 · 06-16-2005, 04:50 PM

Why can't I pass smog?, What the F#&%! is going on? Here are the measurements.

15 mph 1525 rpm HC Max 141 Meas. 203
15 mph 1525 rpm CO Max 0.99 Meas. 3.79

25 mph 1745 rpm HC Max 113 Meas. 196
25 mph 1745 rpm CO Max 0.79 Meas 3.00

15 mph 1525 rpm NO Max 1148 Meas. 160
25 mph 1745 rpm NO Max 978 Meas. 153

Can anyone make some sense out of these numbers?

Moke81
Frustrated in California
1981SC

jtkkz · 06-16-2005, 04:51 PM

My freind has a different car but could not pass either, then he changed his catalytic converter and passed.

DavidI · 06-16-2005, 04:55 PM

I know it is a bit of a drive from the Bay Area, but TRE in North Hollywood could probably solve your problems......

David

stlrj · 06-16-2005, 05:07 PM

Those numbers are telling me that your engine is set too rich.

Before dumping money into parts you don't need, why not invest in a CO adjustment allen or take your car to a shop and have your CO set to spec.

Cheers,

Joe

Grady Clay · 06-16-2005, 05:13 PM

Yes.

It is too rich at the tail pipe. The question is why.

It could be a failed or removed catalytic converter. It could be something amiss in the Oxygen Sensor System or Acceleration Enrichment. It might just be out of adjustment/tune or something else.

Take the SC to someone with the right equipment, skills and experience to actually diagnose the problem. Don’t just throw parts at it. If you want to DIY, use the diagnosis to make your own repair and have them retest it.

Best,
Grady

jorian · 06-16-2005, 05:24 PM

We have smog requirements here as well and a local shop will "detune" for the test or fit a temporary cat & exhaust. Maybe your local wrench could do the same?

Jeremy Cottrell · 06-16-2005, 05:26 PM

You should be able to lean it out quite a bit. The NOX will go up but you have a lot of room there. Since the NOX is so low, it indicates that your cat is in good shape. If it doesn't lean out using the adjustment you need to make sure that your O2 sensor system is in order. If the car runs poorly at that lean a mixture you can richen it up a bit after the test. 3% is very rich and the car should run better and have better mileage with the mixture set correctly.

Moke81 · 06-16-2005, 07:44 PM

Its running poorly when cold, meaning I'm having low ideling problems to the point of stalling out until it gets up to operating temp. I've also notice when warm it seems to fluctuate at idel two to three hundred rpm's on occasion.

Vipergrün · 06-16-2005, 08:22 PM

Way too rich.. I passed CA smog with a gutted cat and O2 sensor disconnected. I set the mixture lean to the point it would barely idle.

-B

afterburn 549 · 06-16-2005, 08:51 PM

I know this is crast but those numbers tell me your in Ca and you like it there........

juanbenae · juanbenae's Garage

if i recall this is at least your second crack at the smogging of the car? if i am correct in my recollection what have you done in between the 1st and 2nd attempt? where (if at all) did the number differ from the 1st & 2nd failing test?

if you have a somewhat fresh 02 sensor and cat and still no luck i would take it to these guys>>>Real Mean Garage, any one had work done by them? if its just the mixture adjustment your out of there for under $50 and he will tell you if it will pass or not.

if you are not SURE about the cat or 02 sensor, well then,, thats a berry of a different color...

fastpat · 09:05 PM

Quote:

Originally posted by Moke81
Why can't I pass smog?, What the F#&%! is going on? Here are the measurements.

15 mph 1525 rpm HC Max 141 Meas. 203
15 mph 1525 rpm CO Max 0.99 Meas. 3.79

25 mph 1745 rpm HC Max 113 Meas. 196
25 mph 1745 rpm CO Max 0.79 Meas 3.00

15 mph 1525 rpm NO Max 1148 Meas. 160
25 mph 1745 rpm NO Max 978 Meas. 153

Can anyone make some sense out of these numbers?

Moke81
Frustrated in California
1981SC

Yes, you're too rich at the tailpipe. The rich mixture is cooling the combustion enough to lower your NOx quite a bit. My 49-state Carrera had a lot more NOx than yours (but still well below max), but was well within limits on CO and Hydrocarbons. A cool combustion process produces less NOx. Also, you're so rich that so much of the Oxygen is being used up that there's not enough left to make CO2, that's what causes you to be high in CO.

Your extra unburned fuel may be due to bad plugs, bad plug wires, or other things unique to your K-Jetronic CIS fuel system. I forget, does a 911SC have a catalytic converter? If so, yours may be bad, but as many will tell you, fix the simple things first.

gerard vaglio · 06-16-2005, 09:24 PM

There are two shops in your area that I'm sure could get you to pass if you don't need to DIY. SCarGo and High Tech Auto, both in San Rafael.

Rob at SCarGo got my car to pass, after adjusting the CO he accompanied the car when it went to the testing center and made additional adjustments based on information the testing equipment gave him during a pre test.

I think he charged me $200, well worth it in my opinion.

Good luck.

dvkk · 06-17-2005, 02:14 AM

Quote:

Originally posted by Jeremy Cottrell
. Since the NOX is so low, it indicates that your cat is in good shape.

I disagree. The low NOx is due to the extra fuel cooling the combustion temps like fastpat said.

FI is too rich.

jryerson · 06-17-2005, 05:53 AM

HC is unburned fuel, a misfire would be over 600ppm and dead miss 1200ppm, you just need to lower the mixture CO to factory specs which would be around 1.2 or so depending on the year and your car will pass and run better as well, this will lower the HCs as well.

Carbs cars generally run richer, I have my CO set to 2.5 on one of mine and HCs are around 250.