First I would like to say that I have been around here for quite some time, but never actually posted (mainly because I was too lazy to get an ID).

Second, I just recently moved to the Chicago area, and found out that I have to pass emissions. Luckly, none of the emissions stuff was taken off of my car, as I only bought it about a year ago, and didn't have money to spend on it. The car is basically stock, but i am slowly modifiying it. right now, i only have a 140 deg temp in it. I was wondering what all the tricks were for passing emissions, as i have recent plans to put in some pretty good stuff, ie cold air, 58 mm TB, 30 lb injectors, ignition. just to name a few.

Information needed--- 1989 Firebird Formula 350
stock tpi
Flowmaster exhaust - Single cat (the guy before didn't know what he was doing, and no it was not the early car with the single cat originally.)
stock auto tranny.
no modifications except those above.

 

anyone have any suggestions??? please

 

Phoenix,

You will have a lot of difficulty getting through the lane with only 140° coolant temperature.

The cold air intake, larger throttle body, and ignition replacement shouldn't affect the emissions at all if done correctly. The larger injectors will probably affect the mixture and therefore emissions, and simply installing larger injector won't get you any performance gains if the rest of the engine is stock. With different heads, cam, or intake/exhaust modifications, the fuel requirement can change. Stock injectors are sized pretty closely to the fuel delivery needs of the stock engine. Since the valves can start floating and ignition tends to lose spark energy at around 5,000 RPM anyway, the stock engine really doesn't require fuel delivery past that point.

Get the engine back to 200°F coolant temperature. Make sure the A.I.R. system is working, and the EGR is functioning. Verify that the oxygen sensor is sending the right signals, and you should blow the sniffer without too many problems.

 

Vadar,

Just out of curiousity, Why would the 140 deg temp affect how the emissions would work. I mean its still above the mark where the engine idles in start up mode. Many ppl have sadi that this will only help me?? I'm just kinda curious on ur take for this.

Phoenix

 

The 140 degree thermo may keep the engine ECM in "Open loop" operation longer upon cold startup. Mine sometimes does not go into "Closed Loop" operation until 130-135 degrees, but usually its around 120 degrees.
If the computer is in "open" loop, then that means the computer is not controlling any of the fuel or timing, its using what was"preset" in the computer. If it is in "Closed" loop, then the computer is constantly adjusting the fuel and timing based on the O2 sensor readings and rpm, maf/vac readings. Most will not pass the sniffer test at idle if in "open" loop.
But if your car is good and hot and you don't have to wait half an hour before they inspect it, you should have no problems if the cat is functioning properly.
*
Any other reason why you think it may not pass??

 

Phoenix,

There are several coolant temperature related parameters in the ECM EPROM that will not enable until the temperature is well above 140°F (60°C) and some that don't enable until it reaches 158°F (70°C):

[i]EVAP canister purge enabled above 70.3°C (158.5°F)

Hot closed-loop timer enabled above 70.3°C (158.5°F)

Acceleration enrichment multiplier at 1.00 below 80° C (176°F)

Diagnostic communication enabled at 70°C (157°F)

Knock Control enabled > 67°C (153°F)

Knock sensor disabled below 66.5°C (152°F)

Target IAC idle RPM >80°C (176°F)

Highway Mode spark advance > 59.8°C (140°F)

Cooling fan duty cycle at 100% at 80°C (176°F)

Code 13 (oxygen sensor fault) enabled above 70°C (157°F)

So while the engine may pass the sniffer at that temperature, it isn't going to get a lot of help from the ECM.