About a month ago, I went through insepction and failed for not having a third brake light. Today, I went to go fail again (I don;t have the lgiht mounted yet) and they told me I was passed the 45 days and had to go completely through inspection again.

Last time I went through, I did not have headers, custom ram air, !TB coolant, hypertech chip, 160 stat. The result in emissions while running at approx 200:
standard my reading
NOx: 1110 459

Now that I have all of those mods, SLP headers, ram air, !TB coolant, hypertech chip and 160 stat, while running at about 220, heres what I got:
standard my reading
NOx: 1110 1107

Dangerously close this time. I don't know what affected it more this time... the increase in coolant temp while taking the test, the chip, the headers? Anyway, I foudn this interesting and wanted to share it.

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1989 Chevrolet Camaro IROC-Z
L98 - 350c.i. TPI, rebuilt 700R4 auto w/shift kit, Dual catalyst Monza PaceSetter Cat-Back, SLP 1 5/8 Coated Headers, 3.23 Posi rear, Hypertech chip with 160stat, Under-Drive pulleys, AFPR, K&N's, !Air Box w/ Ram Air, moddified MAF, throttle body coolant bypass, Spohn SFC's on order, Alarm, Keyless entry, remote starter, 92 Z28 AeroWing, Brand New Paint (6/21/01)

Future: ZZ4 TPI w/EGR, T56, 3.42 or 3.73, Spohn strut tower brace and LCA's

1989 Chevrolet Celebrity Eurosport
2.8 MPFI, no mods
225,000 miles and still ticking!

More info and pics on my webpage:http://go.to/iroc-z

AOL IMer: GPA 0point0

 

An increase in oxides of nirogen is most commonly associated with elevated combustion temps. 3 most common reasons for this are:

1. Timing is advanced. The custom chip probably has a more aggressive timing curve and will increase combustion temps. If you advanced the timing from it's stock setting this will only make the situation worse

2. EGR not working correctly. EGR gasses reduce combustion temps by diluting the intake mix with inert (already burnt) exhaust gasses.

3. Running lean. Million reasons why this might happen including vacuum leaks, the modified MAF sensor, fuel pressure set too low, etc, etc.

 

Take out that 160 stat and put a 180 in. Also, chuck that Hypertech chip. I bet it'll run better, and definetly be more emissions friendly. You may need a heated O2 sensor now that you have headers. Keep in mind you're flowing more air now, and may not be getting enough fuel. If you have access to a scan tool, look at your BLM's and INT. values. Shoot for 128 using an AFPR, or better yet burn your own chip. If you're way off (I'm guessing your number will be around 140, thats what my 91Z was with similar mods,) a chip reprogram might be necessary to keep you from being overly rich at WOT.

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-Jason M. 1991 Camaro Z28