Cat is original. 131,000 on the car. All of the other numbers are well within range. The "smog tech" says the cat isn't suspect - it's running too rich.

In all honesty, I want my turbo to run rich. I just don't want it rich during the smog test!

If the O2 is new, then mixture change is for you! Get a 3mm allen and bend it to clear the top if the engine compartment and try an 1/8 turn at a time.

Alex

Dude, I feel your Pain
 

I just took my 911 SC in to e-chump today, and while the emissions passed in flying colors, the car failed the stupid GAS CAP leak inspection. I was suprised, since they have never been able to test this before, but i have dutifully ordered my new gas cap, with second day to Ohio.

Wankers. :mad:

Chuck

Emission, do you have a cam in that 930? What other Mods? I purchased my 930 a year ago w / all kinds of mods on it, didn't know it at the time. It passed the smog test fine. As I read the posts, I am so afraid and am pissing in my pants. one more year to enjoy it. Jeff

My mechanical mods are limited to a larger turbo (K-27) and a wastegate dump pipe. Neither should change smog readings.

With a recent tune & valve adjustment, new cap, rotor, plugs, and new O2 sensor... my issue is mixture. I am running too rich.

I wouldn't worry until you see the words FAIL on the screen.

Emission,

I have advised posters to lean their mixture many times. Since you are already at .81% CO and only have to get down to .61 I am concerned because that is both extremely low, and a very small amount of a change. It seems that 1/8 of a turn on the screw is worth about 1% so I would just nudge that screw down just a little. A Gunson Gastester is only accurate to .5% so I don't think one will help you.

Also, get that CO back up to the sweet spot ASAP after the test. .61% sounds absurdly lean to me.

OK, question time:
since his mixture is controlled by the lambda circuit, how is adjusting the mixture slightly going to change anything? Am I missing the boat?
Seems to me that unless you disconnect the O2 sensor or lean the adjustment out so far that the frequency valve goes out of range you aren't going to change anything except the mixture before the O2 sensor heats up and kicks in. I need to scratch my head on this one.

I had lots of problems with independent smog shops. Same with my wifes BWM. We ended up going to an independent shop that specializes in german cars.... no more problems. pass everytime. I really think that the smog only shops just don't know how to deal with german cars..

"Test Only" stamped atop your registration usually means you don't get to go to your favorite shop for certification. However, my car went to my mechanic to pretest, he set the A/F, then it went to the test only station.

A few extra bucks, sure, but small potatoes to get past this stressful time.

I just had my smog done this weekend and was very scared. I had to travel down to Woodland Hills to my regular guy as I passed before. Check out my results:

15 mph

CO2 14.1
O2 0.00
HC 47
CO .53
NO 783


25

CO2 14.1
O2 0.00
HC 90
CO .53
NO 848

cab83_750, what gear? Second both times? What RPM for each?

Congratulations on passing!

Not sure! I suspect he did something funny as my RPM ranges are:

15 mph 2,533
25 2,385

What RPM readings do u have?

Emission,

Remember a few months back when you were mocking me for you bought the 930 I was looking for!!!!!! That's karma (sp?) for you!!!!

BWAH! HAR! HAR1



Just kidding man. I loved your car. Hope you pass next time around.

15 mph in 1st @ 1959 RPM

25 mph in 2nd @ 1939 RPM

Having a tall 4-speed sucks for this test.

I never drive the car at such a low RPM. :mad: I'm not in the mood to deal with it this weekend, so next week I'll work on the mixture and get it tested again - and pass, of course.

Oh, after I pass I'll rig a device to pump diesel fuel into the exhaust (like those acrobatic planes) and leave white contrails as I drive by each DMV.... yahoooooo....... :p

But that's after the cat, remember. Before the cat it may be as high as 2%.

So how can that be so absurdly lean?

Joe

Emission, we both failed CA smog this week. Turns out in my case the oxygen sensor was indeed bad. Replaced it with the universal type and the improvement was dramatic.

I posted the latest results in the first post of this thread:
http://forums.pelicanparts.com/porsche-911-technical-forum/177094-ca-smog-test-failure-unexpected-results-help.html


Are you sure your new oxy sensor is connected properly?

You just planted a seed of doubt.

My new 02 sensor is in-line with a new air/fuel mixture reading device (spliced off the same wire). The 02 sensor is in, but I still haven't hooked up the device (loose wire right now). When I hook it up, it will confirm operation of the 02 sensor.

Once again, too lazy for a "this weekend" project. Maybe Monday night...

stlrj,

Good point. I forgot about the cat. I don't have/need one on my car here in Ontario.

BTW do you know:

1 Were these cars required to run @ .61 back when new?

2 Is a rise from .61 to about 2 % typical for after cat versus pre cat measurements?

sammyg2,

I think what we who were advocating leaning the mixture were thinking was that, since the O2 sensor was working correctly (which now may not be correct) then leaning by turning the mixture screw may bring the CO down. I'm thinking that maybe even something like a WUR could be slightly off, which could also be adjusted, if reqd. All this as long as everything else is OK...frequency valve, thermoswitch, cold start injector not leaking, etc. etc,etc.

Paul,

I believe 0.61% is an allowable maximum as the cat ages and losses its effectiveness. If the cat were new, the CO at the tailpipe would most likely be so low as to be hardly measureable.

Joe

The problem is your CAT. They don't last forever, and 18 years is unusually long.
Even with the way its tuned now, you should expect to see results of less than .02%CO and 5ppm of HC with a new CAT.