Here in Massachusetts we are required to pass emissions testing on registration. The mech I had working on my vette advised me the cars computer was behaving strangely. He described the situation as at idle the engine is running so lean that the exhaust temp is to cool to burn off the emissions. He provided me with the following: at idle the CO (% Volume) 0.34 (1.20 max limit)and HC (ppm) 3186 (220 max limit). At 35 MPH the CO and HC changed dramatically and passed emissions testing.

What's going on here ? Mech advised I find someone who knows the computer very well to debug.

Apprciate any HELP............

You need to supply more of the exhaust makeup for me to calculate and know what the AFR was.

Needed is the C0, HC (ppm), CO2 and Nox(ppm)
If the car did a pretest smog test all of the above would have been reported.

Also to know what the engine was seeing is you need a OBD-I scanner and record the engine parameters. That data can then be analyzed and pinpoint what was failing.

You need to supply more of the exhaust makeup for me to calculate and know what the AFR was.

Needed is the C0, HC (ppm), CO2 and Nox(ppm)
If the car did a pretest smog test all of the above would have been reported.

Also to know what the engine was seeing is you need a OBD-I scanner and record the engine parameters. That data can then be analyzed and pinpoint what was failing.

Damn that sounds too crazy for me!!! Good luck with that!

What has been done lately.. Tune up, oil change? and sensor been changed or need to be changed ? O2 Sensor, MAF, MAP, etc ?

Get it on a scanner and see what is il-behaving !?

With the co @3186 it is running extremely rich, if the car was lean the exhaust temperature would be hotter not cooler, check for a bad injector, or blocked air filter, fuel press. too high or something along those lines nox was probably near 0 with that much co, nitrogen and oxygen combine @ 2300 degrees to form nox.