Calif SMOG test failure (Pre-test)
02-09-2004, 01:36 PM
#16
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Ah, thanks Danno. I have actually been checking out your site for quite some time and it seems to be a very good place for information. I'm planning on going to the SMOG center again today to try another pre-test with the stock chips and #0 FQS setting. Hopefully I can get it to squeak by with that set-up.
Regards and much thanks to all.
Aleks
Regards and much thanks to all.
Aleks
02-09-2004, 02:05 PM
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Aleks951 - I changed back to my stock chips when my car failed the rolling smog test and they did nothing to the results. I was only able to drop the NOx readings by changing the cat. Unfortunately, I still have to get the car sorted as to why the NOx readings are so high to begin with. My AFM checked out but I suspect it could be my wastegate. If I come up with any answers I'll post them but once I passed...I parked the car as I have a new toy to sort out...a Mercedes C36. Which had NOx of 4ppm BTW.
02-09-2004, 02:14 PM
#18
Three Wheelin'
I was able to pass rolling smog test with my overly rich chips. In closed loop mode, mixture is controlled by the oxygen sensor, not the chip mapping. Since you are running lean (high NOx) at steady-state 15 and 25 mph, the first thing I would check/change would be my O2 sensor. This is what corrected mine and several other cars. If NOx is still high, the cat may be the problem. Was it fully warmed up? I can't see how the AFM or chips would affect mixture in these tests if the O2 sensor is controlling mixture.
Some people disconnect the oxygen sensor for more "performance." Check that out first.
Good luck.
Some people disconnect the oxygen sensor for more "performance." Check that out first.
Good luck.
02-09-2004, 05:57 PM
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Well I guess I know what I'll be doing today after work.... and yes, the car was very warm and the tech even let it run for awhile to let it heat up even more.
02-09-2004, 06:55 PM
#20
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"In closed loop mode, mixture is controlled by the oxygen sensor, not the chip mapping. "
"I can't see how the AFM or chips would affect mixture in these tests if the O2 sensor is controlling mixture."
Actually it's both. The procedure is that the DME first picks up air-flow meter voltage and RPM to look up data in the 3D maps:
Then other minor adjustments are made for air-temperature and O2-sensor feedback. But these added up don't account for more than a +/-3-5% change maximum from the values dictated in the fuel maps. So the chip-mappings have to be pretty spot-on with actual flow-rates in order for the O2-sensor to dither above and below the map the same amount.
"Some people disconnect the oxygen sensor for more "performance." Check that out first."
Yeah, if your O2-sensor is bad, disconnecting it will have the DME ignore the O2-sensor and rely on just the chip-maps alone:
Depending upon what region of the World you're in, your DME will be set to use one of 3 fuel-maps. For some strange reason, Australia gets its own separate map, but it's the same as the ROW/Japan/California map above so I only listed the two different ones. Notice that the USA map is the richer than the ROW maps and most of the time, the O2-sensor will be telling the DME to lean out the mixture. That's why when you disconnect the O2-sensor, you end up with a richer mixture. Whether or not this actually gives better performance is based upon our air-flow rates. If you have flow-increasing mods, then increasing fuel will probably help. However, in a stock car, it most likely will hurt performance. Remember that '60s saying?
Also, European (ROW) cars don't have catalytics or O2-sensors, so the fuel-mappings have to be exact with no dependency on the O2-sensor to make minor adjustments. Thus the larger range between minimum & maximum fuel-values in the ROW/Japan/Calif. maps to match actual airflow patterns. Japanese emissions are actually much tougher than Calif. and all cars have to meet the same standards across the board; no sliding scale based upon age. It's so strict that you have to replace your engine every 16k-miles or so because the ring-wear allows too much blow-by gasses to pass emissions.
"I can't see how the AFM or chips would affect mixture in these tests if the O2 sensor is controlling mixture."
Actually it's both. The procedure is that the DME first picks up air-flow meter voltage and RPM to look up data in the 3D maps:
Then other minor adjustments are made for air-temperature and O2-sensor feedback. But these added up don't account for more than a +/-3-5% change maximum from the values dictated in the fuel maps. So the chip-mappings have to be pretty spot-on with actual flow-rates in order for the O2-sensor to dither above and below the map the same amount.
"Some people disconnect the oxygen sensor for more "performance." Check that out first."
Yeah, if your O2-sensor is bad, disconnecting it will have the DME ignore the O2-sensor and rely on just the chip-maps alone:
Depending upon what region of the World you're in, your DME will be set to use one of 3 fuel-maps. For some strange reason, Australia gets its own separate map, but it's the same as the ROW/Japan/California map above so I only listed the two different ones. Notice that the USA map is the richer than the ROW maps and most of the time, the O2-sensor will be telling the DME to lean out the mixture. That's why when you disconnect the O2-sensor, you end up with a richer mixture. Whether or not this actually gives better performance is based upon our air-flow rates. If you have flow-increasing mods, then increasing fuel will probably help. However, in a stock car, it most likely will hurt performance. Remember that '60s saying?
Also, European (ROW) cars don't have catalytics or O2-sensors, so the fuel-mappings have to be exact with no dependency on the O2-sensor to make minor adjustments. Thus the larger range between minimum & maximum fuel-values in the ROW/Japan/Calif. maps to match actual airflow patterns. Japanese emissions are actually much tougher than Calif. and all cars have to meet the same standards across the board; no sliding scale based upon age. It's so strict that you have to replace your engine every 16k-miles or so because the ring-wear allows too much blow-by gasses to pass emissions.
Last edited by Danno; 02-09-2004 at 10:19 PM.
02-09-2004, 07:51 PM
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I for one do not see how a wastegate can cause a lean condition.
The air is measured by the AFM/MAF/MAP then the computer adds fuel to match. This all occurs way upstream of the wastegate. The only control sensor the wastegate could possibly impact is the O2 sensor. In that scenario the wastegate would have to completely divert the exhaust flow, effectively bypassing the O2 (which I do not think possible). If this is what is happening, you would also not see any boost from the turbo.
Also remember the O2 loop is only allowed to control a finite amount of the air/fuel ratio. The O2 loop can not compensate for large discrepancies in the air/fuel mixture. This is why a lean mix can and will kill your engine. The O2 is not a fail safe devise that can dump fuel into the cylinders.
And on a stock exhaust system the wastegate has its own cat.
Take the car to someone that can troubleshoot the systems and repair them. You will spend twice the cost, blindly replacing parts in an attempt to find the solution.
The air is measured by the AFM/MAF/MAP then the computer adds fuel to match. This all occurs way upstream of the wastegate. The only control sensor the wastegate could possibly impact is the O2 sensor. In that scenario the wastegate would have to completely divert the exhaust flow, effectively bypassing the O2 (which I do not think possible). If this is what is happening, you would also not see any boost from the turbo.
Also remember the O2 loop is only allowed to control a finite amount of the air/fuel ratio. The O2 loop can not compensate for large discrepancies in the air/fuel mixture. This is why a lean mix can and will kill your engine. The O2 is not a fail safe devise that can dump fuel into the cylinders.
And on a stock exhaust system the wastegate has its own cat.
Take the car to someone that can troubleshoot the systems and repair them. You will spend twice the cost, blindly replacing parts in an attempt to find the solution.
Last edited by Bill; 02-09-2004 at 09:55 PM.
02-11-2004, 02:14 AM
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Thanks for the advice and yes Bill it makes sense. I took it to another service shop in the area that deals with German cars but not specifically or does not specialize in Porsches only. In any case, they did an emissions failure analysis and found:
"O2 sensor rose above 16.8% on SNAP test. HC rose to 27000PPM on sec crank test".
So they replaced my O2 sensor and performed a "decarbonizing" service to clean intanke & fuel inductions system. Afterwards NO dropped from:
15MPH (was 1628) now 1052ppm
25MPH (was 1346) now 1099 ppm
It looks like we're heading down the same rabbit hole as others did. They now recommend replacing the catalytic convertor and they gave me the reason they recommend it but I don't have it on my receipt since I declined having them do that service at this time.
So we're about 300-400ppm away on the NO emissions. Do you think that replacing the cat at this time would resolve the issue? If not, why not? Remember that the car has 122K miles on it and I believe it to be the original cat.
Or should we be looking in a different direction?
Thanks again!
"O2 sensor rose above 16.8% on SNAP test. HC rose to 27000PPM on sec crank test".
So they replaced my O2 sensor and performed a "decarbonizing" service to clean intanke & fuel inductions system. Afterwards NO dropped from:
15MPH (was 1628) now 1052ppm
25MPH (was 1346) now 1099 ppm
It looks like we're heading down the same rabbit hole as others did. They now recommend replacing the catalytic convertor and they gave me the reason they recommend it but I don't have it on my receipt since I declined having them do that service at this time.
So we're about 300-400ppm away on the NO emissions. Do you think that replacing the cat at this time would resolve the issue? If not, why not? Remember that the car has 122K miles on it and I believe it to be the original cat.
Or should we be looking in a different direction?
Thanks again!
02-15-2004, 10:57 PM
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How do I spell relief? P-A-S-S
I finally passed my smog test on my 951. After checking the AFM, any vacuum leaks (none), replacing stock chips (had APE), replacing O2 sensor (definitely helped), decarbonize intake (did nothing for emissions), we finally swapped out the catalytic converter.
Since CAT prices varied from ~$550.00 for aftermarket (through online Porsche parts vendors) to MORE THAN $1900.00 for new OEM part from Porsche I went with a local muffler shop (Santa Clara Muffler) who said he'd install an aftermarket CAT for me and if it didn't pass, I wouldn't have to pay.
Sensing the "no loss" situation on my part I figured the worst that could happen was it didn't pass and I'd have to go with another CAT vendor. However, I wanted him to make me a copy of the Fabspeed cat bypass set-up since I was replacing all that. I also told him that it had to be 3" pipe.
So, in order to keep his costs to a minimum (for the test only) he cut out the old cat section, plumbed the wastegate pipe upstream of the new cat and then fab'd the removable cat section. Upon picking it up, I drove it around and it seemed ok with a bit more rumble in the exhaust. Unfortunately before I got home I heard a "ka-tink" noise and then a big exhaust leak ensued.
I was not happy. So I parked the car and went to bed. In the morning I looked underneath and what happened was that a bolt/plug for an O2 sensor in the CAT came loose. I called the shop and retrieved a replacement. All sounded good and I was off to the SMOG test-only facility.
Here were my results of the test after O2 sensor AND cat replacement:
15 MPH:
HC - measured = 40 max = 116
CO - measured = .10 max = .74
NO - measured = 663 max = 791 :O (close but it counts for passing)
25 MPH:
HC - measured = 11 max = 91
CO - measured = .02 max = .62
NO - measured = 35 max = 730
Now I have to drop my car off on Tuesday morning so he can finish making my 3" pipe from exhaust manifold back. He will then also provide me with a 3" 'test pipe' section from when I take the car out to the track.
Ahhhhhhhhhh relief!!!!!! I feel so much better now.
I hope this info may help others when they try and pass. Now I get 2 years to play before I have to go through all of this again!
I finally passed my smog test on my 951. After checking the AFM, any vacuum leaks (none), replacing stock chips (had APE), replacing O2 sensor (definitely helped), decarbonize intake (did nothing for emissions), we finally swapped out the catalytic converter.
Since CAT prices varied from ~$550.00 for aftermarket (through online Porsche parts vendors) to MORE THAN $1900.00 for new OEM part from Porsche I went with a local muffler shop (Santa Clara Muffler) who said he'd install an aftermarket CAT for me and if it didn't pass, I wouldn't have to pay.
Sensing the "no loss" situation on my part I figured the worst that could happen was it didn't pass and I'd have to go with another CAT vendor. However, I wanted him to make me a copy of the Fabspeed cat bypass set-up since I was replacing all that. I also told him that it had to be 3" pipe.
So, in order to keep his costs to a minimum (for the test only) he cut out the old cat section, plumbed the wastegate pipe upstream of the new cat and then fab'd the removable cat section. Upon picking it up, I drove it around and it seemed ok with a bit more rumble in the exhaust. Unfortunately before I got home I heard a "ka-tink" noise and then a big exhaust leak ensued.
I was not happy. So I parked the car and went to bed. In the morning I looked underneath and what happened was that a bolt/plug for an O2 sensor in the CAT came loose. I called the shop and retrieved a replacement. All sounded good and I was off to the SMOG test-only facility.
Here were my results of the test after O2 sensor AND cat replacement:
15 MPH:
HC - measured = 40 max = 116
CO - measured = .10 max = .74
NO - measured = 663 max = 791 :O (close but it counts for passing)
25 MPH:
HC - measured = 11 max = 91
CO - measured = .02 max = .62
NO - measured = 35 max = 730
Now I have to drop my car off on Tuesday morning so he can finish making my 3" pipe from exhaust manifold back. He will then also provide me with a 3" 'test pipe' section from when I take the car out to the track.
Ahhhhhhhhhh relief!!!!!! I feel so much better now.
I hope this info may help others when they try and pass. Now I get 2 years to play before I have to go through all of this again!
)
02-17-2004, 04:51 AM
#27
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Hi Guys
I received my smog check notice in the mail about a month ago and as typical
fashion I didn't open the reg. renewal until today. I quickly looked at it and proceeded to take it to the local shell station a few blocks away where I had
my 4x4 tested. I left the car and came back 30 mins later only to find that he
couldn't perform the test.
Like an idiot I didn't read the flyer carefully in the envelope.
It turns out the test can only be performed at a Smog Test Only Center. I said to the guy, why is this? He said, your car is more likely to pollute the air. I said this is bull$#. Now it turns out that the cost of the test just had gone from 59 dollars to 89+, who knows what, because there are only 4 of these
in the Santa Clara area. I had ran the car for about 12 years with a gutted cat off and totaled escort car. I just replace the orig. exaust back about 2 yrs ago. The only engine modification have is the stage 2 chip set from Authority for the Turbo S. I hope it passes . The car only has 48k and I am the original owner. I hope I don't have to go through what Aleks951 had to go through...
I received my smog check notice in the mail about a month ago and as typical
fashion I didn't open the reg. renewal until today. I quickly looked at it and proceeded to take it to the local shell station a few blocks away where I had
my 4x4 tested. I left the car and came back 30 mins later only to find that he
couldn't perform the test.
Like an idiot I didn't read the flyer carefully in the envelope.
It turns out the test can only be performed at a Smog Test Only Center. I said to the guy, why is this? He said, your car is more likely to pollute the air. I said this is bull$#. Now it turns out that the cost of the test just had gone from 59 dollars to 89+, who knows what, because there are only 4 of these
in the Santa Clara area. I had ran the car for about 12 years with a gutted cat off and totaled escort car. I just replace the orig. exaust back about 2 yrs ago. The only engine modification have is the stage 2 chip set from Authority for the Turbo S. I hope it passes . The car only has 48k and I am the original owner. I hope I don't have to go through what Aleks951 had to go through...
02-17-2004, 08:19 AM
#28
Race Director
I'd borrow a stock chip for the smog-test... just to be on the safe side. And get one of those pre-tests and make sure they do only a pre-test and not log anything...
02-17-2004, 12:58 PM
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cas951 - They ran the 15mph test in 1st gear and they went to 2nd for the 25mph test. I was really (incredibly) surprised at how low my NOx went in the 25mph test.
brad-cam - I had the exhaust work done at Santa Clara Muffler. I'm actually dropping my car off there in 1/2 hour so they can complete my 3" system. All he has to do now is make the pipe from the exhaust manifold down to the cat and then he's making me a test pipe. The quality seems decent but for about the same price I guess I could have gotten the Fabspeed product. The major selling point was that they offered me a "pass or don't pay" on my catalytic converter since another shop referred me to them. I guess I can give you a final "thumbs-up" on the work once they finish it and I get it home and take a peek underneath.
Crazy Eddie - I also hope you didn't have to go through what I had to go through but for me the extra complications were that I was purchasing the car and I decided to do the smog on my own instead of picking the car up after the PO smogged it. At least I know exactly what was done instead of having him do it and then not knowing. I had my "test-only" done at a W. San Carlos Smog station on West San Carlos just West of Meridian. Very nice Vietnamese guy who runs and owns the shop. He is extremely polite and accomodating to his customers. In fact, he told me that at times he even works PAST 8PM because customers keep coming in to get their cars tested.
Danno - Regarding the pre-test. While "officially" nothing is logged, DMV is notified of the pre-test so they do know what happens on your pre-test. I had this verified by 3 shops and they all say that DMV is getting really strict on it. I guess if you had to test emissions you'd have to go to a shop that has a machine to do that but it isn't their SMOG machine. Yep....sux. But at least I learned a lot from the experience.
I also learned that SMOG test and pre-test prices are not "set" by DMV so if you shop around you might be able to find something for less.
Good luck Crazy Eddie. If you don't have stock chips, I'll be pulling mine out this weekend probably so I can let you borrow them. HOWEVER, I will need them back since I want to make sure I have them for the next SMOG test (if I need them) - just in case.
brad-cam - I had the exhaust work done at Santa Clara Muffler. I'm actually dropping my car off there in 1/2 hour so they can complete my 3" system. All he has to do now is make the pipe from the exhaust manifold down to the cat and then he's making me a test pipe. The quality seems decent but for about the same price I guess I could have gotten the Fabspeed product. The major selling point was that they offered me a "pass or don't pay" on my catalytic converter since another shop referred me to them. I guess I can give you a final "thumbs-up" on the work once they finish it and I get it home and take a peek underneath.
Crazy Eddie - I also hope you didn't have to go through what I had to go through but for me the extra complications were that I was purchasing the car and I decided to do the smog on my own instead of picking the car up after the PO smogged it. At least I know exactly what was done instead of having him do it and then not knowing. I had my "test-only" done at a W. San Carlos Smog station on West San Carlos just West of Meridian. Very nice Vietnamese guy who runs and owns the shop. He is extremely polite and accomodating to his customers. In fact, he told me that at times he even works PAST 8PM because customers keep coming in to get their cars tested.
Danno - Regarding the pre-test. While "officially" nothing is logged, DMV is notified of the pre-test so they do know what happens on your pre-test. I had this verified by 3 shops and they all say that DMV is getting really strict on it. I guess if you had to test emissions you'd have to go to a shop that has a machine to do that but it isn't their SMOG machine. Yep....sux. But at least I learned a lot from the experience.
I also learned that SMOG test and pre-test prices are not "set" by DMV so if you shop around you might be able to find something for less.
Good luck Crazy Eddie. If you don't have stock chips, I'll be pulling mine out this weekend probably so I can let you borrow them. HOWEVER, I will need them back since I want to make sure I have them for the next SMOG test (if I need them) - just in case.
02-17-2004, 04:38 PM
#30
Rennlist Member
Dano and Alek ,
I just call the smog center that I have to go to called Green Slip and they told
me that a pre test is 59.00 and does not get applied towards the actual test
which is 89. w/ certif. So the question is 1- will they allow me to pretest
without a record of it ? I will call them again to insure that and 2- will my car pass w/ the autothority chips. I wisely saved the orig chips (thanks Alek anyway) But I really don't want to pull those boxes out and swap those chips
out. Sh#$ . Did anyone on this board pass the new inspection with an Stage 2 Authority chip only (and of course the Banjo bolt with a smaller orifice) please let me know .... Thanks in advance
Ed
I just call the smog center that I have to go to called Green Slip and they told
me that a pre test is 59.00 and does not get applied towards the actual test
which is 89. w/ certif. So the question is 1- will they allow me to pretest
without a record of it ? I will call them again to insure that and 2- will my car pass w/ the autothority chips. I wisely saved the orig chips (thanks Alek anyway) But I really don't want to pull those boxes out and swap those chips
out. Sh#$ . Did anyone on this board pass the new inspection with an Stage 2 Authority chip only (and of course the Banjo bolt with a smaller orifice) please let me know .... Thanks in advance
Ed