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GS DP w/Race CAT FAILS CA Smog...BOO!!

3K views 21 replies 12 participants last post by  perkj 
#1 · (Edited)
This past Saturday I failed smog on my 2000 Viggen with the GS DP & Race CAT. It failed the NO on the 15 mph:
...............%CO2.......%O2.....HC(PPM)....CO(%) .....NO(PPM)
15 MPH:.....14.9.........0.0.......25............0.09 .........513*
25 MPH:.....14.9.........0.0.......19............0.08 .........374

*FAILED: max is 430

On my last SMOG Check 2 years ago (prior to putting on the GS DP) my numbers were:
...............%CO2.......%O2.....HC(PPM)....CO(%) .....NO(PPM)
15 MPH:.......15.1........0.01.......11..........0.01 .........45
25 MPH:.......15.1........0.00........8...........0.0 0.........45

On Sunday I put the stock DP back on (only thing changed) and went in for the free retest today at the same place and passed with flying colors:
...............%CO2.......%O2.....HC(PPM)....CO(%) .....NO(PPM)
15 MPH:.......15.2........0.00.......3............0.01 .........0
25 MPH:.......15.1........0.00.......1............0.00..........0

I was amazed to the the NO on the retest go down from 513 to 0.....seems that the Race CAT on the GS DP does its job of not setting off a CEL, but isn't quite adiquate to pass smog out here in Cali.

Now to reinstall the GS downpipe and 6-point brace....in total its 4 hours wasted to remove/replace and remove/replace again.

Nick: may want to think about providing a DP with a larger more effective CAT for those of us in CA with this ultra strict SMOG Check. On Saturday the guy doing the SMOG laughed when he saw how small the CAT was.
 
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#3 ·
Do they run the smog test at higher RPMs if the engine is tuned? Europe has the same strict laws as Cali, maybe worse. I have the GS 3 "down pipe and race cat with a flowmaster 40 series muffler. I didn't tell them it was tuned and it passed with flying colors, no questions asked.
 
#6 ·
Car is running perfect....fuels trims are all right on, O2 sensors are all within range, compression is well within spec, zero vaccum leaks, plugs have less than 5K on them are gapped within spec, no CEL, etc etc. California Smog is quite strict now compared to any other state. California requires all of the sniff tests to be run on an rolling dyno at 15 mph and 25 mph to simulate real world driving vs. just the only standing still RPM tests.

A failure on the NO(PPM) is due to one of two things (1). either a bad CAT or a CAT not up to smog spec or (2) too high of combustion temps

Just the mere fact that by changing the DP only and nothing else and the issue was solved shows that its due to the CAT not been capable to adhereing to CA's CARB Smog specs. It should be noted as well that the GS DP is less than a year old. As I'm sure you know, the stock DP has 2 CATs....the first of the CATs is the smaller one, yet it is still larger than the one on the GS DP and then there is the 2nd one which is over twice the size of the one on the GS DP. I think if GS would put one of the larger high flow CATs, say similar to the one on JAKs DP, there won't be an issue given that when it failed, it just barely failed.
 
#12 ·
With stock software you can end up with some odd fuel trims running modified hardware. The short term will fight the long term since the flow is so much higher.

The problem is everybody wants cheap.. This is still a $120 cat. Problem with the ceramic cores is they do not like the high output cars. You end up with a short lifespan. Every car here locally we put a $50 Catco on has failed! I am running this same cat as production dp in my Vig and it is still in good condition. We experienced so many other cat failures I had to make and loan out gauges.. Who is going to buy a downpipe that was $200 or $300 more than existing. Or do I just put a $50 cat in it and expect it to only last 1 year.
 
#14 · (Edited)
With stock software you can end up with some odd fuel trims running modified hardware. The short term will fight the long term since the flow is so much higher.
Thanks Nick, I will get the fuel trim data logs tonight.

Though Swedishassassin saw the same issue issue two months ago, failed in CA with high NO, on his Stage 4 SW: http://saablink.net/forum/showthread.php?t=26719

The problem is everybody wants cheap.. This is still a $120 cat. Problem with the ceramic cores is they do not like the high output cars. You end up with a short lifespan. Every car here locally we put a $50 Catco on has failed! I am running this same cat as production dp in my Vig and it is still in good condition. We experienced so many other cat failures I had to make and loan out gauges.. Who is going to buy a downpipe that was $200 or $300 more than existing. Or do I just put a $50 cat in it and expect it to only last 1 year.
Just curious, what brand CAT is on the GS DP....looks to be a Dynatech PowerCat at first glance
 
#18 · (Edited)
So your car was pretty much running a tad lean so to speak. Next test try this and this goes for all Ca high NOX cars:
Put the lowest octane gas in the car.
Drive the piss out of car before you smog it and keep it running while you are waiting.
Inflate tires to over 45 psi, less friction the better.
Turn on your heater full blast in the car while they are testing. But before make sure your cooling system is in perfect order.
Make sure they place a fan pointing at front of car.
Last but not least and is super important, HAVE THEM TEST CAR IN FIRST AT 15 AND SECOND at 25. Nothing states that they have to test in second and third. The only prob. is that they will have to find the sweet spot in first and half the guys are lazy as hell and just put it in second and third.
My car had about the same readings. The tech told me to do all of the above and low and behold, 4 days later it passed.
Good luck
 
#22 · (Edited)
Nick,

Below is the data logger of a run with the stock DP on....with my understanding of FTs, there doesn't appear to be anything out of whack here....it appears the STFT is doing its job since the LTFT is staying constant and not doing any adjustment. So it appears the car itself is in working order. I run another data log with the GS downpipe to see if my LTFT start shifting.

Time.................RPM.....STFT (%)..LTFT (%).Air Flow Rate (lb/min)
07:03:39.000.......916........0...........4.68.........0.52
07:03:40.000.......888........0.78.......4.68.........0.52
07:03:41.000.......893........0...........4.68.........0.52
07:03:42.000.......915........0.78.......4.68.........0.51
07:03:43.000.......1086......0...........4.68.........1.71
07:03:44.000.......1429......0...........4.68.........1.76
07:03:46.000.......1554......-2.34......4.68.........3.79
07:03:47.000.......2749......-2.34......4.68.........4.86
07:03:48.000.......3571......0.78.......4.68.........5.36
07:03:49.000.......4033......0.78.......4.68.........1.73
07:03:50.000.......2381......9.36.......4.68......... 6.86
07:03:51.000.......2771......-1.56......4.68......... 5.11
07:03:52.000.......3015......0.78.......4.68......... 3.96
07:03:53.000.......3168......1.56.......4.68......... 2.38
07:03:54.000.......3171......2.34.......4.68......... 1.58
07:03:55.000.......3096......6.24.......4.68......... 1.49
07:03:56.000.......3031......3.12.......4.68......... 1.31
07:03:57.000.......2921......0...........4.68......... 1.18
07:03:58.000.......2769......-0.78......4.68......... 1.08
07:03:59.000.......2653......-3.12......4.68......... 0.96
07:04:00.000.......2528......-0.78......4.68......... 0.9
07:04:01.000.......2368......-3.12......4.68......... 0.82
07:04:02.000.......2008......0...........4.68......... 0.67
07:04:03.000.......1314......-4.68......4.68......... 0.6
07:04:04.000.......951........-6.24......4.68......... 0.57
07:04:05.000.......1499......-6.24......4.68......... 1.84
07:04:06.000.......2109......-7.8.......4.68......... 4.44
07:04:07.000.......3228......-3.9.......4.68......... 6.04
07:04:08.000.......3759......0...........4.68......... 1.51
07:04:09.000.......2253......8.58.......4.68......... 5.72
07:04:10.000.......2592......-1.56......4.68......... 3.26
07:04:11.000.......2763......3.9.........4.68......... 3.48
07:04:12.000.......2914......4.68.......4.68......... 3.8
07:04:13.000.......3029......2.34.......4.68......... 2.7
07:04:14.000.......3055......7.8.........4.68......... 2.73
07:04:16.000.......3207......7.8.........4.68......... 4.42
07:04:17.000.......3268......2.34.......4.68......... 1.6
07:04:18.000.......3199......9.36.......4.68......... 1.55
07:04:19.000.......3057......7.02.......4.68......... 1.34
07:04:20.000.......2963......3.9.........4.68......... 1.28
07:04:21.000.......2902......0...........4.68......... 2.57
07:04:22.000.......2963......2.34.......4.68......... 3.61
07:04:23.000.......3106......0...........4.68......... 3.82
07:04:24.000.......3220......2.34.......4.68......... 2.24
07:04:26.000.......3036......5.46.......4.68......... 1.31
07:04:27.000.......2761......1.56.......4.68......... 1.08
07:04:28.000.......2413......-2.34......4.68......... 0.87
07:04:29.000.......1968......-2.34......4.68......... 0.69
07:04:30.000.......1249......-4.68......4.68......... 0.61
 
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