Turbo/SC emissions question

[ca2822]

I've been searching through threads for days about the pros/cons of a turbo setup vs. supercharger... I'm not looking to get into discussions and debates about which is better or worse and all that.

My question is, is it possible to pass emissions with a twin turbo setup, such as the SOS kit, with cats? Can the car be easily tuned to pass? Similarly, does anyone know if the SOS supercharger should pass an emissions test?

 

[Semnos_NSX]

Neither one is CARB certified so in California they definitely will not pass legitimately. I’m not sure how strict Texas smog laws are….

 

[DucatiCraig]

I am ignorant about Texas emissions laws as well.

Since you have a 1992 nsx, you are OBD1, and do not have to pass a code reader test.

Most likely, you have to pass a sniffer test and a visual cat check.

If this is the case, you need to have cats (well, temporarily at least...:biggrin, and pass a sniffer test, which isn't too hard to do with a turbo setup.

You need to find out more about emmissions testing in Texas to see if there are other compliance criteria.

May sound archaic in this interweb age, but quick way to find out is to go to a testing center and just ask what they check for on your car...


- C

 

[ca2822]

In my specific county they don't do emissions. I am in the military though and will be moving around and not sure if I'll have to get tested in the future. I guess my real question is, if I have a twin turbo set up, is it feasible to down tune it to pass a sniffer test. Same question for superchargers... can you have them tune specifically for a brief period of time just to pass emissions?

 

[Myaddiction]

If you have fully functioning cats (300 or 400 cells) installed and the rest of your emissions equipment is working (egr, etc..) there is no need to "down tune" a set up that has a good tune in the first place. All the emissions test take place in the vacuum part of your maps. As long as you tune it for 14.7 afr in those areas were they should be anyway you'll pass a sniffer test fine.


Of course in CA they don't care if it actually works or not if it doesn't pass visual.

 

[angus]

With my turbo kit is would be very easy to pass a sniff test by installing a cat.

 

[dynomike]

the only way to pass emissions on a turbo/sc setup is to run the stock computer with stock fuel injectors. It is possible to pass emissions with a aftermarket computer but you will have to really play with the tune aggressive ignition retard will be a must to keep noX down. Where the car will fail will be on nox because of the lack of proper EGR valve control. If you are running a Piggyback ECU in conjunction with the stock ECU you will have better luck. But in my opinion piggyback computers are completely crap and lead to nothing but problems

 

[ScienceofSpeed]

We have passed several of our supercharger and turbocharger systems through AZ emissions which have the same standards as Texas. One of the twin turbocharged NSXes that we completed for NSXPO was from Texas. We passed emissions in Arizona, and the customer subsequently passed the emissions test in Texas. All cars have had AEM EMS and larger injectors (550-1000 cc).

The tests are performed at load points below positive pressure. So, careful attention to low load tuning of fuel, ignition, and O2 feedback is required. A five gas analyzer helps, but can be done with out.

-- Chris

 

[BATMANs]

I wish the Turbos would pass visual tests.

The SOS SC can easily pass visual since it looks identical to the Comptech one with the CARB EO # to the untrained eye.

http://www.arb.ca.gov/msprog/aftermkt/devices/aftermktdevice.php

Not sure about other states, but if you were stationed in California and had to smog the car keep in mind that it's not legal to change the position of the OEM cat converters.

 

[WillErickson]

the only way to pass emissions on a turbo/sc setup is to run the stock computer with stock fuel injectors. It is possible to pass emissions with a aftermarket computer but you will have to really play with the tune aggressive ignition retard will be a must to keep noX down. Where the car will fail will be on nox because of the lack of proper EGR valve control. If you are running a Piggyback ECU in conjunction with the stock ECU you will have better luck. But in my opinion piggyback computers are completely crap and lead to nothing but problems

I passed with ease here in Denver (they do a dyno run up to 60 mph) with 550's and the AEM FI/C, tuned by Chris at SOS. This was not a "tune it so it will pass emissions" but a normal, conservative (rich) tune. I'm using the high boost autorotor s/c.

What is so bad about piggyback computers? The FI/C does what it needs to do, and has very good driveability.

 

[peiserg]

I passed a couple times no problem with my NA2 running 550 injectors/walbro high pressure pump using the fic. no retuning done. here in arizona, if you are obd2, they just plug into the port, and check for codes. no code, no problem. i do have race cats. SOS cats, actually.

i'm curious too, as to why the fic is crap? from the viewpoint of a non-tech who just drives, it seems great.

 

[captainjman]

We have passed several of our supercharger and turbocharger systems through AZ emissions which have the same standards as Texas. One of the twin turbocharged NSXes that we completed for NSXPO was from Texas. We passed emissions in Arizona, and the customer subsequently passed the emissions test in Texas. All cars have had AEM EMS and larger injectors (550-1000 cc).

The tests are performed at load points below positive pressure. So, careful attention to low load tuning of fuel, ignition, and O2 feedback is required. A five gas analyzer helps, but can be done with out.

-- Chris

Do you know about Illinois emission law as well. Since meeting with you I went to a testing facility but each person there seemed to have a different answer. A list of states with pass / non-passable criteria will definitely be useful on prime!!

 

[croftoncustoms]

View attachment 126753Blast from the past but I'm curious if anyone can shed some light on my emissions text failure.

SOS SC. Stock air box. ARK exhaust, high flow cats.Tuned at SOS and then again here in Albuquerque due to elevation change. I just bought the car and it has not needed a E-test untill now. Any tips or suggestions would be greatly appreciated.

 

[jwmelvin]

Holy hydrocarbons! Do you have an AFR gauge in the car? It must be super rich.

 

[croftoncustoms]

Yeah. I can pull exact numbers from if tomorrow compared to RPMs.

 

[croftoncustoms]

Went around town and it looks like the AFR is sitting around 14 at all RPMs at all speeds. Even at idle (1000RPMs) I was reading 14.

when I punched it I was seeing 11,12,13,14s. Hard to see while driving and due to the location of the guage.

 

[jwmelvin]

It should be 14.7 at (warm) idle and any other time the ECU is performing closed-loop control. So high hydrocarbons seems odd. That said, I'm not the person to correlate sniffer results with operating conditions. Our emissions test here in VA is just an OBD2 scan.

 

[peiserg]

hopefully after almost 6 years since he asked, he figured out the fix

 

[neuronbob]

I know this is an old thread. I am lucky that here in Ohio, my NSX was eligible for a collector plate. This removes the requirement for emissions...convenient, since I am now running a SOS TT system with high flow cats, on an AEM Infinity ECU. Were my car not eligible for the collector plate, I’d have to do a sniffer/visual check.