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Hib Halverson directed me to his post on the ZR-1 Net and I thought I'd post it here as well. From Hib:
Hi Zroners-
A while back, I asked some questions here about cats. These questions arose out of trouble I was having getting my car though California's hated Smog Check.
As it turned out, the trouble I was having was not really cats but that the People's Demokratik Republik of Kalifornia (a near-communist state located west of Nevada) had raised the standards used by the Smog Check program such that previously legal cars will fail in-spite of having all emissions-related systems working properly.
The California Smog check uses a chassis dynamometer to load the car at two speeds, 15 mph and 25 mph, which (hopefully) simulates real world conditions better than does just a emissions test done at idle.
The problem was my 95 was right on the upper limit of oxides of
nitrogen (NOX) during the low speed test. In some test sessions, was flunking. It took me five tries--three "pretests" after which I changed cats and tried other idea and two for real tests in which the car flunked the first test then passed an hour later--to get my car where the state would renew my tags for 04.
During this process of pretests and tests, I discovered that the reason my car passed in 01 and not in 03, in spite of having virtually the same NOX emissions, was the state raised the standard. In 01 the limit was 988 ppm NOX. In 03 the limit was 689 ppm.
Why did the state raise the standards? Well, that's a complex story which might be the subject of my column in Hemmings Muscle Machines later this fall but, in short, the CA Smog Check was designed and "sold" to the CA legislature and EPA using some computer models which attempted to predict to the future effectiveness of the program. Now, after a decade or more of the program, the California Air Resources Board is finding out that the actual results of the program are falling short of those models so,
to appease the liberal environmentalists who control the state's legislature, CARB wants to force some older cars off the road (because what can you do with a previously legal car that is running properly but won't pass other than sell or scrap it) so they are incrementally raising some standards such that cars which were once legal, but might have been high in the range of allowable emissions, will now fail.
In 01 my car put out about 800 ppm, just under the 988 standard. In 03 my NOX was still 800-880 ppm but now over a "new" 689 ppm standard.
Well....****. I'm not going to sell it.
During my pretests at my ace "smog guy" Quality Auto Service in Pomona California, while owner Mike Garabay ran the tests, I watched the ECM's serial data stream with my Vetronix Mastertech scan tester. I noted that, during each of the 15 mph tests, EGR was not enabled. That would obviously impact NOX and I noted that fact for future reference. I also noted that at 25 mph, the car was well under 706 ppm standard (which also had been raised from the previous 848 ppm) at 480-550 ppm.
During this period of emissions tests, I also did some very controlled on-road testing with the Mastertech in the car and I determined that the O.E., 93-95 calibration had the EGR valve enabled at 17 mph and disabled below that. Obviously, if the CA Smog Check low speed test is at 15 mph, the EGR valve's function, vital to lowering NOX emissions, would not be available.
The solution was simple.
I called Ron Zimmer, my long-time calibration engineer, and asked him if he could burn me a cal. exactly the same as what the ECM had now, but with the EGR enabled at 14 mph instead of 17. "No problem, " Zimmer said, "Come on down." So, I was off to Z-Industries in Temecula CA to pick-up Zimmer's revised "14mph EGR" cal.
Long-story short: I put the revised calibration in the ECM and went for a pretest at Quality Auto Service and, viola!, the NOX was now 483ppm, significantly under the new, 689ppm standard.
There may be other Zroners in California with 93-95s that flunk the NOX test in the low speed part of the Smog Check. If there is nothing wrong with the car that would cause it to flunk NOX, your problem might be a combination of the car's normal NOX emissions, the revised, higher NOX standard used by the Smog Check program and the EGR not enabled at 15mph. If that's the case, the easy solution is to change to one of these Z-Industries chips with the lower-speed, EGR enable. It opens the EGR at 14 mph, reducing NOX such that you pass and, for you environmental whackos out there, making the car's emissions lower than they were when it was new.
There are other states that use the CA-style emissions test in either unchanged form or a modified form determined by those states' air quality regulatory bodies. If your state has a CA-style or "ASM or Acceleration Simulation Mode" type test which uses a low speed test at 15 mph and your NOX standard is down in the high 600s or low 700s ppm, this Z-Industries calibration fix may also work for you. Contact Z-Industries at 909-303-6857 or at remmizr@aol.com.
90-92s don't have EGR valves so, obviously, none of this applies to those cars.
H. Halverson
Technical Writer
Content supplier to
automotive Internet and print media
Hi Zroners-
A while back, I asked some questions here about cats. These questions arose out of trouble I was having getting my car though California's hated Smog Check.
As it turned out, the trouble I was having was not really cats but that the People's Demokratik Republik of Kalifornia (a near-communist state located west of Nevada) had raised the standards used by the Smog Check program such that previously legal cars will fail in-spite of having all emissions-related systems working properly.
The California Smog check uses a chassis dynamometer to load the car at two speeds, 15 mph and 25 mph, which (hopefully) simulates real world conditions better than does just a emissions test done at idle.
The problem was my 95 was right on the upper limit of oxides of
nitrogen (NOX) during the low speed test. In some test sessions, was flunking. It took me five tries--three "pretests" after which I changed cats and tried other idea and two for real tests in which the car flunked the first test then passed an hour later--to get my car where the state would renew my tags for 04.
During this process of pretests and tests, I discovered that the reason my car passed in 01 and not in 03, in spite of having virtually the same NOX emissions, was the state raised the standard. In 01 the limit was 988 ppm NOX. In 03 the limit was 689 ppm.
Why did the state raise the standards? Well, that's a complex story which might be the subject of my column in Hemmings Muscle Machines later this fall but, in short, the CA Smog Check was designed and "sold" to the CA legislature and EPA using some computer models which attempted to predict to the future effectiveness of the program. Now, after a decade or more of the program, the California Air Resources Board is finding out that the actual results of the program are falling short of those models so,
to appease the liberal environmentalists who control the state's legislature, CARB wants to force some older cars off the road (because what can you do with a previously legal car that is running properly but won't pass other than sell or scrap it) so they are incrementally raising some standards such that cars which were once legal, but might have been high in the range of allowable emissions, will now fail.
In 01 my car put out about 800 ppm, just under the 988 standard. In 03 my NOX was still 800-880 ppm but now over a "new" 689 ppm standard.
Well....****. I'm not going to sell it.
During my pretests at my ace "smog guy" Quality Auto Service in Pomona California, while owner Mike Garabay ran the tests, I watched the ECM's serial data stream with my Vetronix Mastertech scan tester. I noted that, during each of the 15 mph tests, EGR was not enabled. That would obviously impact NOX and I noted that fact for future reference. I also noted that at 25 mph, the car was well under 706 ppm standard (which also had been raised from the previous 848 ppm) at 480-550 ppm.
During this period of emissions tests, I also did some very controlled on-road testing with the Mastertech in the car and I determined that the O.E., 93-95 calibration had the EGR valve enabled at 17 mph and disabled below that. Obviously, if the CA Smog Check low speed test is at 15 mph, the EGR valve's function, vital to lowering NOX emissions, would not be available.
The solution was simple.
I called Ron Zimmer, my long-time calibration engineer, and asked him if he could burn me a cal. exactly the same as what the ECM had now, but with the EGR enabled at 14 mph instead of 17. "No problem, " Zimmer said, "Come on down." So, I was off to Z-Industries in Temecula CA to pick-up Zimmer's revised "14mph EGR" cal.
Long-story short: I put the revised calibration in the ECM and went for a pretest at Quality Auto Service and, viola!, the NOX was now 483ppm, significantly under the new, 689ppm standard.
There may be other Zroners in California with 93-95s that flunk the NOX test in the low speed part of the Smog Check. If there is nothing wrong with the car that would cause it to flunk NOX, your problem might be a combination of the car's normal NOX emissions, the revised, higher NOX standard used by the Smog Check program and the EGR not enabled at 15mph. If that's the case, the easy solution is to change to one of these Z-Industries chips with the lower-speed, EGR enable. It opens the EGR at 14 mph, reducing NOX such that you pass and, for you environmental whackos out there, making the car's emissions lower than they were when it was new.
There are other states that use the CA-style emissions test in either unchanged form or a modified form determined by those states' air quality regulatory bodies. If your state has a CA-style or "ASM or Acceleration Simulation Mode" type test which uses a low speed test at 15 mph and your NOX standard is down in the high 600s or low 700s ppm, this Z-Industries calibration fix may also work for you. Contact Z-Industries at 909-303-6857 or at remmizr@aol.com.
90-92s don't have EGR valves so, obviously, none of this applies to those cars.
H. Halverson
Technical Writer
Content supplier to
automotive Internet and print media
