passed california emissions

willabeest

willabeest

Experienced Member
Joined
15 September 2004
Messages
737
Location
sacramento california
i passed this time. the short version is that i changed the air cleaner, oil, filter, used premium chevron gas rather than costco premium. the long version is that i noticed that when they ran the 15 MPH test they ran it at a higher RPM than the time i failed. i think that on manual shift cars they may have a choice as to what gear they run. if that is true then different RPM may create different conditions for the test. so 25 MPH in second gear might have more emissions than 25 MPH in first gear. i tried to warm up the cats and have them run the test immediately but despite my pleading and then arguing the testers at smog 'n go were convinced that i didn't need to warm them up and waited probably 15 minutes before they finally ran the test. passive-aggressive SOB's IMHO. i may not go back to that testing station in the future. at least not for my NSX. thankyou for all the suggestions.
 
demigod said:
I have Comptech headers, high flow cats, and exhaust. They had to warm up the cats before mine would pass..but I'm just glad it did. :)
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these jokers claimed warming up the cats was pointless and they were sure i was going to fail again and just to piss me off the technician came back to argue with me (and let the cats cool off) before they re-tested it.
they only way i could control myself was to plan on taking them to small claims court if it failed. i think i would have had a good case because i had arranged to warm up the cats just before the test with the desk guy, who agreed. he must not have talked to the technician. "smog'n go" . wonder if i could file a complaint with the BBB.
 
Glad to hear that it passed. Its usually minor stuff like air filter, plugs, etc that cause a stock or lightly modded NSX to fail and I'm glad the easy fixes did it for you.

It's possible that it would have passed the first time if it wasn't a Smog N Go. Those guys generally don't know how to get most cars to pass, especially if the TECH thinks warming up the cats doesn't help.
 
mickeylex said:
Glad to hear that it passed. Its usually minor stuff like air filter, plugs, etc that cause a stock or lightly modded NSX to fail and I'm glad the easy fixes did it for you.

It's possible that it would have passed the first time if it wasn't a Smog N Go. Those guys generally don't know how to get most cars to pass, especially if the TECH thinks warming up the cats doesn't help.
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i also turned off the traction control. i saw the look on the tech's face when i passed. he had assured me i would fail again. i have been talking to some people at work and a lot of them have worse stories than mine. seems to me the NSX club should rent out a smog station and figure out what works and doesn't work to get NSX's to pass. i also think testing during the winter puts one at a disadvantage. i may try to change it to summer somehow. i wanted the acura dealer to change the plugs but they said that was useless. so they saved me a little money. i will get the numbers and post them.
 
willabeest said:
these jokers claimed warming up the cats was pointless and they were sure i was going to fail again and just to piss me off the technician came back to argue with me (and let the cats cool off) before they re-tested it.
they only way i could control myself was to plan on taking them to small claims court if it failed. i think i would have had a good case because i had arranged to warm up the cats just before the test with the desk guy, who agreed. he must not have talked to the technician. "smog'n go" . wonder if i could file a complaint with the BBB.
Click to expand...

I've watched my car's smog readings realtime with the cats hot, then cold, then back to hot. With the dyno smog, you have 60 seconds to pass and you don't need to shorten that by having to wait for the cats to 'wake up'.
 
W said:
I've watched my car's smog readings realtime with the cats hot, then cold, then back to hot. With the dyno smog, you have 60 seconds to pass and you don't need to shorten that by having to wait for the cats to 'wake up'.
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if i understand you correctly then on the dyno smog the emissions must slowly decrease the longer you are on the dyno?

also - why would the traction control have an effect?

TIA.
 
willabeest said:
also - why would the traction control have an effect?

TIA.
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TCS would engage because the rear wheels would be spinning while front not moving - the air/ fuel mix is adjusted by the ECM to reduce the "wheel spin"
I think it would have been obvious if the original test did not have TCS cancelled.
 
'the air/ fuel mix is adjusted' is a very nice way of saying 'fuel cut'. The hard fuel cut creates very lean mixes, so lean as to not ignite, which would then spike the HC and O2 levels.

These numbers are high for a good running car, so something is still amiss. Is your Comptech header Carb certified? Early on, Comptech used DC Sports headers. On the early versions, the O2 bung on the DC header sampled only one piston of a bank instead of the entire bank. My car with DC headers was marginal on emissions due to high HC.

If you don't know for sure, then look under the car at the collector of the front header just in front of the cat. It will be under the oil pan. If its an early header, there will be no O2 sensor at this collector.

Ripped from SOS, this shows a header with the O2 bung between the collector and the cat flange, which is the good way of doing it:
header_kit_450.jpg


Also, when were the plugs last changed?
 
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D'Ecosse said:
TCS would engage because the rear wheels would be spinning while front not moving - the air/ fuel mix is adjusted by the ECM to reduce the "wheel spin"
I think it would have been obvious if the original test did not have TCS cancelled.
Click to expand...


The traction control on the NSX adjusts the throttle to control wheel spin.
 
D'Ecosse said:
TCS would engage because the rear wheels would be spinning while front not moving - the air/ fuel mix is adjusted by the ECM to reduce the "wheel spin"
I think it would have been obvious if the original test did not have TCS cancelled
Briank said:
The traction control on the NSX adjusts the throttle to control wheel spin.
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Click to expand...
My quote was taken directly from the FAQ -

Traction Control System (TCS)<!--mstheme-->
The goal of the Traction Control System (TCS) is to minimize rear wheelspin on slippery or uneven road conditions. This unique development was created as a high-performance system rather than purely a low-speed, traction-enhancing device. The TCS, whose 1997 enhancements allow for more precise control, uses the wheel-speed sensors of the Anti-Lock Braking System (ABS) and a G-sensor to detect rotational differences between front and rear wheels. If the computer determines the surface is slippery, Central Processing Unit (CPU) signals are sent to decrease the amount of air and/or fuel delivered to the engine. The driver can disengage the TCS via a switch on the instrument panel. Using ABS wheel-speed sensors and working in conjunction with the drive-by-wire throttle system, the TCS engages at impending wheel-slip rather than at the moment of wheel-slip. A logic circuit also controls stability during sudden deceleration on slippery surfaces. For 1997, the system has also been enhanced to further reduce shift shock during manual downshifts with automatic transmission-equipped models

In a throttle by wire system, technically I suppose it could be possible to control the throttle, however on an OBDI there is just mechanical linkage between the pedal & the throttle - no electronic intereference (or assistance) there.
 
The electrical interference is there.

From the 1991 online service manual, page 19-75 describes the TCS and control system.

"will then signal the throttle actuator and PGM-FI control unit to reduce engine power."

Kinda looks like the throttle actuator is the cruise control motor.
 
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Section 19 page 78 of the on line manual shows the lost motion assy. and actuator motor that is used by the TCS to change the throttle plate position regardless of the position of the throttle cable. The ECU also receives signals from the TCS computer but I believe the throttle plate control is the main way the TCS controls wheel spin. Also looking at the quote from the FAQ's there is no "G sensor" on the NSX so the whole write up is suspect as to it's accuracy.
 
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Having read quite a few posts about NSX not passing smog test. I was a bit worry myself for the bi-annual Calif. smog check.

Well, it failed the first time and it barely passed the second time on the 'NOx'. The smog tech. was surprise that it didn't pass the first time since mine has only 63k miles (1992). I drove around to warm up the cats. before the test. The only different on the 2nd test is that the tech. just rev. the engine in the 3k range for 5 - 10 min. before the test.

Checked with my mechanic afterward, he said the cats are getting weak. He said that there is some chemical to clean or unclog the cats. Not sure if anyone has tried it.

My reason for writing this post is that the cat. for the NSX must have some flaws. According to the smog tech., other older/much higher mileage (toyota, honda etc) cars passed without any cat. issues. :confused:
 
Attached are recent results from my 1991 NSX with CTSC (high-boost version) and 42k miles. Passed by VERY large margin.
 

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