Failed Emissions!!!

[jd3443pd]

Okay guys, need some help here. Just took the car for it's emissions test and failed, the HCO and CO tests. Basically the mechanic said that the car is running too rich. This is what I've got a 1993 T/A with the LT1 and 160,000 mi and 6 spd. I just did an install on a new opti, MSD cap and rotor, E3 plugs, new Autolite 8mm wires and electric water pump conversion. The car has a fairly new catalytic converter (replaced w/in the last 500 mi.). I got a great deal on the car and was told the opti was bad and had been misfiring and dumping raw fuel into the old cat and that was why it got the new cat. Now would old deteriorated vaccum lines cause this? Could the o2 sensors have been damaged by the raw fuel that was dumped on them? The car does seem to idle a little high (about 900-1000RPM). The only other thing besides all new brakes, is that I did the throttle body bypass of the radiator hoses. I read the codes in the computer and the only code is a 12, which means no distributor signal (duh the car isn't running so there won't be any signal). No other codes like low voltage @ the o2's or anything else. So somebody out there give me some ideas on where to start. Oh other than running a little rich the car now runs like a scalded dog!!

Thanks Jason

[Injuneer]

DTC 12 means the diagnostic system has been activated. Its the "handshake" that indicates you have established communications to flash the codes on the SES light. It has nothing to do with the distributor or anything else.

Need details about any mods to the engine, or is it pure stock? For example, if you have headers, the O2 sensors may have been relocated, and on the 93, that can be a problem, because that is the only year LT1 without "heated" 4-wire O2 sensors, and moving them away from the engine with headers can cause problems.

Being speed-density, two items that need to be checked are the inlet air temp sensor and the MAP sensors. Both those are critical for the ECM to calculate the mass air flow rate and set the fueling. Also check the coolant temp sensor. If its reading too low, it will cause the ECM to richen the air/fuel mix, since is assumes the engine is still cold. A "scan" with a real scanner (not a "code reader") would answer all these questions.

Look for exhuast leaks before the O2 sensors. Check for misfires. Sound like a lot of new parts in the ignition (I wouldn't use "gimmick" plugs like the E3's) but is it possilby misfiring?

Could be leaking injectors. Pop the fuel raills, pressure the fuel system and look for drips.

Could be faulty O2 sensors.

What kind of cat did they put in it? I see a some people on eBay selling replacement cats with the AIR pipe connection on the middle of the cat. They tell you it will work on anything, but it won't replace the single bed three-way cat in your 93.

[00 Ragtop Z]

agree with Fred--could be that they installed a hi-flow cat or low restriction cat which will cause it to code and perhaps not pass inspection (my 92 RS didn't.

[Jeff_in_Atl]

How far did you drive it before you had the emissions tested? It's not just a matter of the engine getting up to temperature. The converters have to be hot in order for them to function.

You can idle a car for an hour and it will fail the emissions test. Take it out and drive it at 60mph for 10 minutes and it will pass with flying colors.