[BigEnos]

So, my Maxima *just* missed passing emissions last time. MD tests 3 things, NOx, CO, and HC. HC it passed but NOx and CO it was just out of spec on. I don't have the specific numbers here, but I could get them if it would be helpful. Any suggestions about what I can do to help the car pass? I am already planning to install a new O2 sensor (car probably needs it anyway), and the car had a new pre-cat and cat about 2 years ago. AFAIK they are still good. I've heard that a little alcohol in the gas tank will help. Any truth to it? Any other tricks like that? Like I said, it was close so just a little "bump" would probably do it.

TIA

This post has been edited by BigEnos: Mar 9 2006, 04:55 PM

[CrashTestDummy]

I have a friend who is really into Ni$$ans. They are cheaper by the dozen. :-)

IIRC, the EGRs are problemmatic, and a pita to replace. You have to pull the intake. With age, they will frequently have issues with vacuum lines, especially the ratsnest that goes under the intake. Make sure all the ones you can see and get to are good. The comments Mike had were good. Here is what I usually do on a car that is about to undergo its first emissions test:

plugs, wires, cap, rotor. You will be amazed what a difference wires can make, even factory replacements.
O2 sensors, especially if the ones on the car are more than a year old. Spend a little time on the Nissan lists, or ask someone who knows Nissans on what the best brand for those cars are. Some have to have factory parts, some are okay with aftermarket.
fuel filter, air filter.
If the thing uses a vane air meter, make sure the door operates properly.
If the thing uses a MAF, use a MAF cleaner on it, especially if you are using a K&N type air filter (one of those with oil on the media).
verify the TPS is properly adjusted and clean.
change the oil and filter just before going for the inspection. If you fail and have to go back, change the oil again.
Make sure the car is good and warm before going in. Drive on the freeway for 10 minutes, or so before stopping in, to make sure the cats are as hot and clean as they can be.

If it still doesn't pass, there is an additive called 'Guaranteed to pass emissions', or something like that, by CRC you can try. I haven't tried it yet, but it may work. Other than that, you are probably looking at replacing the EGR, CATs, or both, as well as looking for vacuum leaks and failing switches/ported vacuum valves.

Good luck!