Failed Emissions...BARELY! Can any help diagnose my problem?

[Siizzzoooo]

It is a 93 S13 coupe w/ 155k miles, the motor is a 97 KA w/ 90k miles, used 93 intake and exhaust manifold, so those have 155k as well

HC is 325, with 220 allowableCO is 1.29 with 1.20 allowable

anyone have any ideas?

I think the timing may be slightly off, but I'm not sure what else it could be...maybe a misplaced or switched vacuum plug, but other than that I'm not sure...

Any help would be great!

-So

[Bigvinnie]

It could be a few things.Could be that you are not using the 93 cams with the 93 ecu.Could just be your O2 sensor.I would more than likely think it is your cams smaller lobe and duration on intake side. The 91-93 ecu's run really rich your probably just choking the engine and running more fuel and less air on the lift and duration.

[InsanityInc]

that's a bit more than barely.

But, your CO is high, which means you're running rich. If your cams were the problem, only HC would be high.

So, my guess would be either that:

Your TPS needs adjustment (pretty likely)Your O2 sensor is dead (semi-likely)Your Coolant Temperature Sensor is dead(very likely)

O2 sensors and CTSes are cheap to replace, and adjusting the TPS is easy. So, do those and you should be good.

[240crawler]

Since when do we have emissions testing in TN?

[MikeMurphy]

http://northwestnissans.com/bo...rcare

that was my post on NWN. Includes some "mods" that helped me out substantially in those departments.

[MikeMurphy]

When is the last time you replaced your coolant temp. sensor?