I have a 94 GT with AODE---175K miles with remanufactured motor that previous owner installed about 30K miles ago. It was MI car and now Ohio car and I need to pass emissions. After some minor stuff (PCV, air filter, clean MAF, water pump, plugs, cap and rotor, drivers side O2 sensor, fuel filter) failed emissions with high HC, CO and Nox. I don't have CEL showing. Car somewhat hard to start cold and idles rough--? timing off?. I know that this has been posted before but it seems that there are a million things to fix or replace to get this passed thru emissions and I don't know where to start. Also, is this vehicle supposed to have 4 catalytic converters? If it has 4 I am down 2 and that would explain why I can't pass. I'm sure this gets old for you guys that really know what you are doing so I apologize. Any and all help would be appreciated.

 

use at least 89 gas..retard timing to say 6 or so..reset tps...clean t/b..try some bg products fuel injector cleaner..also

 

OK more info. Since I don't have the back 2 cats my air tube from the smog pump was cut off and welded shut (now I know why that pump sounds so loud). I am having the tube reinstalled into the exhaust. How much effect does this air have on emissions (ie...HC, CO and NOx)? Computer check this past weekend showed normal function of all sensors, EGR functioning normal, fuel pressure normal. If reinstallation of the air tube doesn't get this passed I will have to replace the 2 forward cats. Any suggestions on replacement H pipe with cats or does anyone have good used equipment for sale? Thanks for the input.