Hi All...

This doesn't really have any S2k content, but I thought those of you with older vehicles or that are performance minded might find this interesting.

Vehicle: 1991 Trooper 2.6L 4 cylinder

Old (Pre-dyno) testing levels:
Speeds: Idle, >2500RPM
HC (ppm): 220
CO (%): 1.20
Dilution (%): 6.00

New (as of May) ASM (dyno) levels:
Speed: 25mph
HC (ppm): 151
CO (%): 1.68
NOx (ppm): 956
Dilution (%): >6.00

Speed: 15mph
HC (ppm): 155
CO (%): 1.31
NOx (ppm): 1046
Dilution (%): >6.00


As you can see, they got stricter (at least CO) and they test for NOx. Now, what my truck blew:

Old (Pre-dyno) testing levels:
Speed: Idle
HC (ppm): 8
CO (%): 0.00
Dilution (%): 14.50

Speed: 2500RPM
HC (ppm): 3
CO (%): 0.01
Dilution (%): 14.61

This was bone stock, but after a tuneup (plugs, wires, cap, rotor, O2 sensor, EGR). This is what I suspect the truck did when it was new.

Here's what it did with no smog pump, no cat, no EGR, intake, header, and exhaust:

Speed: Idle
HC (ppm): 108
CO (%): 0.76
Dilution (%): 14.36

Speed: 2500RPM
HC (ppm): 21
CO (%): 0.73
Dilution (%): 14.73

Still passed!

Finally, for the recent (new) test, I put the cat back on- all the other mods were there, and the smog pump and EGR still gone:

Speed: 25mph
HC (ppm): 17
CO (%): 0.01
NOx (ppm): 109
Dilution (%): 16.10

Speed: 15mph
HC (ppm): 28
CO (%): 0.03
NOx (ppm): 231
Dilution (%): 16.30

Still passed.

FWIW, the emissions level requirements vary with age and weight, and get more lenient for older, lighter cars. Larger vehicles have stricter limits as well as newer ones.