triscadek

Come to think of it , I remember, a timing adjustment on the DME and it took a special tool to turn the socket but the guy made one out of a golf Tee.

But I can't find/don'tremember where I saw it and am not sure what year it was for. Too many Pcar sites. I don't recall ever seeing that here though.

And I haven't smoked any crack today.

Flight_951

As for the adjustable timing, I thought I was the only one still with an air flow meter and non-adjustable timing, sorry. :-)

The afm measures air flow at all rpms, but should assist in controlling a/f ratio at low to moderate rpms (not wot, which use the chip maps). If the afm is malfunctioning, idle and part throttle operation may be lean (with high NOx), or rich.

Anyway, that's where I am now... New afm sitting on the bench, waiting to install a new thermoswitch first (fans not running properly). Then I need to get the CO set with the new afm. Then it's off to the emissions test for Round Three.

H2Opumpr

I have been going through this for at least 4 years now here in California.
Just got my car smogged last week on the rolling dyno like always.

This time I barely passed NOx. Last year I blew through the NOx portion easily after getting a used cat off Ebay. I redid the rings this winter and added Guru Chips and barely squeeked by on NOx (by 6ppm). It was interesting what you said about reringing your motor causing high NOx numbers. I was always under the impression it was usually high combustion chamber temps. Most smog techs see me pull up and tell me to run the motor for 10 minutes before the test, I think this helps if you are high or over the limit on Hydrocarbons but has the inverse effct on NOx numbers. Don't let the car run for too long before the test it makes a big difference. Next time I will reset the FQS switch to back off timing and let the car run for a lesser time to reduce combustion temps a bit.

Also here in California the required NOx number to pass decreases every year. I have looked at all of my past test sheets and the minimum number(ppm) has decreased every year!.... Even though my car does not get cleaner every year, the f*#$&ers at the AIR resources board somehow think it should!

Obviously, it is an attempt to get older cars off the road, sort of a forced renewel program.

BTW...If you get a really good or new three chamber cat it will clean up almost the dirtiest of motors.

Flight_951

Northern Virginia has reduced the limits across the board on their rolling tests by 30% in the past two years. I hadn't heard a word about that until my car failed the test and I started looking into it. Our limits weren't even that high to begin with...

H2Opumpr

just pulled my smog test sheets and......


1999 max for NOx was 2138 ppm @15 mph
1938 ppm @ 25 mph

Early 02 Max for Nox was 1146 ppm @ 15 mph
1006 ppm @ 25 mph

Late 03 Max for Nox was 1125 ppm @ 15 mph
955 ppm @ 25 mph


The same applies to HC's too..!

Hey, I'm all for doing my share but c'mon, you must be kidding, look at the drop from '99 to '02.

Unfortunately....,my car was engineereed to produce a certain number at a certain time('86) and to get more stringent every year will force my car off the road. However, I feel I'm up to the challenge and I know they won't win!
I will just have to go to the next level and not burn Gasoline in the motor for the next test!

SidViscous

If they keep getting more stringent in Cali. Ya'll give me a call will ya. Be happy to come out and get it from ya.

Flight_951

-----------------
Virginia 2001
-----------------
NOx limit:

1323ppm - 15mph
1208ppm - 25mph

-----------------
Virginia 2003
-----------------
NOx limit:

972ppm - 15mph
885ppm - 25mph

Jay W

Well I am in the same boat... I took the 924 in for emissions test in Missouri TODAY and got bad news too. Anyone got a good n/a cat for not too much money? Not a good day for Porsches and emissions.

Matt Sheppard

I got my '87 951 to pass CA smog by welding in a generic cat section into the test pipe, then welding in the srtait section again after registration.

I'm going through smog now with my '90 DSM. I just bought a high-flow cat from JEGS. I will use more disgression and connect the sections w/ T-bolt clamps instead of welds and then I can use the same cat on all my cars whenever it needs testing.

To get my '86 951 to pass last time, since it's stock, I had to fit 3 different downpipe/cats to find one that "sniffed" within the margin.

Perry 951

You are exactly correct. Most NO issues are from high combustion temps, but if you have an oil burner, it can bring them up as well. 600ppm overlimit for me, so it's a good combination of both.

Taking away a little timing will help bring temps down. I am not sure if -2.7 degrees from the DME FQS will solve my issues, but last night I tossed in the towel and decided to take away fuel and timing with the FQS switch and re-tune the car. As of this evening, I have it tuned as good as it was before.

A few observations since the timing change. Off throttle backpressure pops are much more common. I pop flames more often as well. (makes sense with the later timing)

Before the timing change, my car had a very pungent exhaust odor. It's not a sweet hydrocarbon smell, but a very sharp strong stench. After chatting with my Guru Father (car guy and chemist), he said I was probably smelling the high level of NO the car was producing. NO is an acidic gas, and carries a very sharp odor. Since the timing change, that has gone away and all I have is a sweet puff or 2 when getting off the gas. At idle, you would think there was a cat on it, almost no exhaust smell at all.

I'm gonna re-test this week without the cat and see how it does. If I fail again, I'll use a cat so it will pass. Application for the Collectors plates will go in before the next E-check (2 years).

Thanks for all the suggestions!!!