Thread: Advice on passing NJ emissions.

I failed NJ emmisions with the following results:

NOx with a reading 2444...the standard is 1134
HC with a reading of 146..the standard is 159
CO% with a reading od .93..the standard is .82

I just barely failed HC and CO% but I violated the NOx reading. I have a 1994B13 with a CAI, header and exhaust. I do have a catco universal cat that I got from Smmuit that's about 2 years old and I don't have an EGR system. I do however have an adjustable fuel pressure regulator. I passed before but this time it was off. Can I run some "dry" gas (alcohol...etc.) and play with the fuel pressure to try to get around this?

My response assumes that NJ uses a dyno sniffer test - variable speeds for about 2 minutes on the dyno. If not, the information below is less relevant.

EGR is what takes the NOX out. Did you car ever have an EGR system? If so, can you reinstall it? If you can get a properly working EGR system on the engine, I think that would take care of the problem.

Also, retarding your base timing should reduce NOX. Perhaps try it at 11 to 12 degrees BTDC. Remember to also reset your base idle or you car will be idling too low.

I recently tested using about 40% E85. I ran the tank to near empty, added 2 gallons of high test and then put in 2 gallons of E85. Then I filled up after the test to dilute the E85 and prevent damage to rubber parts. The E85 had no real effect on HC, NOX or CO. Results for all pollutants tested were within the range of sampling error.

As always, make sure your cat is good and hot when you test. Also check your fuel pressure to make sure its set to factory specs. If you fail again, try changing your fuel pressure by 3psi. This will move all your AFRs by about half a point (like from 14.7 to 14.2 if you increase the pressure) when you are in open loop mode, but you will still be at 14.7 in closed loop. If you richen your mixture a little, it may reduce NOX, but at the risk of increasing HC and CO.

I'm going to try some thermal header wrap next to see if getting more heat to the cat helps (this will be my 6th test failing HC and sometimes NOX).

Thanks for the advice. You are also correct about the 2 min on the dyno. I don't have the EGR anymore because when I installed my first header about 5 years ago the EGR connection leaked so bad at the header that I just ditched the sytem. However I did pass emmisions without the EGR about 4 years ago with the same N/A setup I have right now, I guess I got lucky.

I have been thinking hard about my dilemma and I have a sneaky thing I am going to try. Right now the EBAY header I have has bungs all over that are plugged....I guess so the header can fit almost every SR20 vehicle from 1991-2000. There is a bung on top of the pipe right near the cat connection that I assume is for an O2 sensor on some cars. I have it plugged right now since my car does not require this sensor. I am thinking of unplugging it and letting some exhaust just dump out of this hole. Since the emmisions test is taken from the tailpipe I would assume that when they test it with the hole unplugged the emissions reading will be much lower since I am dumping some exhaust out under the car before the tailpipe! I just hope that you won't be able to notice the new exhaust leak over my magnaflow resonator/flowmaster muffler exhaust. You can't see the hole because it is on top of the exhaust pipe so when they look under the car with the mirrors they won't see it. I am going to unplug the hole today and see what the exhaust sounds like.

You'll definitely notice the leak from the bung if you disconnect it. Not only is it loud, they'll see a hole if they peak under the hood.

What I did in order to pass, is call the shop to set up an appointment, and then go drive the car really hard, pull it in (and leave it idling while waiting), and then the system is still super heated when they run the test.

The catalytic converter is a HUGE help, cleaning up the crap in the exhaust.

I als think that the exhaust will be very loud if you unplug that hole. Getting the cat hot is a good idea. With an exhaust header, you lose a lot of heat that would be retained by the factory set up. Try retarding the timing to 13* also.

Another thing is to reconnect the AIV. This will put additional air to the exhaust stream and make the Cat burn hotter (thus lowering your emissions). The AIV is located in front of the engine. Just something else to try..

Bill.. I need to get by there. Old SR20 finally crapped out and I have now swapped in a JDM DE.. LMK when is a good time..