Herman K

Failed Texas Emissions Inspection

I was going to get my annual inspection done today but to my surprise NOX (ppm) where to high. I’ve attached a PDF file with the good test results from 2009 where you can see that the high speed emission NOX was 471 well below the maximum allowed 751 (ppm)

The bad results of today of the test at 14:50 hrs show NOX at 862 and after we placed an additional cooling fan in front of the car we ran another test at 16:05 where the NOX dropped to 794 but was still over the allowed number of 751.

With NOX being a normal component of combustion I wonder what may be the cause here? I know I have an increased leakage on my water bridge so the coolant doesn’t compress in the cooling system as it should until I fix this.
I have installed a new MAF about 5000 miles ago and don’t think I have any vacuum leaks (but mat have to retest this

Any feed back would be appreciated.

I appreciate all the feed back over the weekend I did do the following things over the weekend.

1 Oil change
2 Changed the plugs (was overdue)
3 Disconnected and plugged the vacuum line from the smog pump ( per Schoki's advice a Porsche procedure

As you can see from the new report it passed with flying colors.

Thanks to all that responded hope fully some else may benefit from this experience in the future.

Happy motoring

SeanR

Just had one fail today also, trying to figure out why.

pcar928fan

Hope this does not happen to mine...yowza...

SeanR

Herman, what Cats are you running?

jeff spahn

Emission tests. . . emission tests..... never heard of them.

Herman K

Sean mine are still the factory originals. Just searched for a bunch of stuff and found this from Schoki >

Just a question: Did you guys disconnect the vacuum line to the air pump check valve? Roger had a similar problem with his GTS. Apparently it is not very well known in the US that the air pump has to be disconnected for the smog test!?
Diconnect the vacuum line to the air pump valve and run the tesy again. This is according to the test procedure manual issued by Porsche in Germany!
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Schocki

Ii's in one of Rogers old threads
https://rennlist.com/forums/928-foru...sion-test.html

I guess that is what I'm goin to try next and after that change back to my previous install MAF that was on the car for the past 5 years when it past all the test

Herman K

Your in the wrong sand box right now..go away or I call my big sister

SeanR

Thanks for that Herman, one of the cars having issues has the smog pump still. I will try that next.

pcar928fan

I would certainly think they should pass from the factory w/o having to disconnect and reconnect stuff... Our cars are old, but still...so far *knocking on wood* none of my (3) that need the smog check have had a lick of a problem and we don't disconnect and reconnect anything to test them...

Don Carter

Herman,

I have failed with high NOX a couple of times over the years. Last time I think a new O2 sensor fixed it. How old is yours? Also, what gear did you run the test in? Better to keep the RPMs high from what I've read. There is a waiver you can get if you spend 100$ or so trying to fix it and it still fails but it's probably a big hastle.

Too bad your car is so new, mine just hit 24 years and I'm done with smog tests. Inspections now cost $14 instead of $40 and all they check is the basic stuff. I'll be removing the cats in a few days to install an X-pipe.

Lizard928

BG 44K intake valve/injector clean.

Run that, and take it for a hard 30 min drive before the test and do not turn off until after the test is done.

pcar928fan

Don and Herman, do you guys have to run your car on rollers for your smog test? We just have the tail pipe sniffer in Austin...wondering if mine would pass under those more difficult tests...

Don Carter

Yes, dyno type machine in Houston, not sure about Dallas. When I read about your cars never failing I was thinking, Austin tests are much easier than Houston's for sure. We had a real popution problem a few years back, but it's getting much better.

Speedtoys

Well, they do keep the WOT and Idle speed stuff working well.

*kidding, had to find a negative to no emissions*

Don Carter

If the car is new enough to have ODBCII, mid 90's I think, you don't use the dyno, they just plug it in.