ok i just went in for an emssions and it failed yet no code issues to even consider it

HCPPm limit 66 reading 146
CO% limit 0.37 reading 0.58
NO ppmlimit 0505 reading 1537

thats at 40km/h

curb idl is
Hcppm limit 200 reading 123
CO% limit 1 reading 0.03
No ppm n/a n/a

now curb idle pass'* but not the 40km

so what causes this

also this car was orginalyl outfitted for 1 02 sensor the 2nd 02 sensor was capped off as the org cat didnt have one

now when i put a brand new exhaust on it since i didnt have option for 2nd 02 sensor i capped off 02 sensor hole on the cat and when i ran it last year it over heated on the intake side of the cat turned red hot then i had to replace it and it also turned red hot
then i just bought a 2nd 02 sensor and had to find out where on the engine where gm capped off the 2nd o2 sensor plug and pluged it in but now i needed to emission it and it failed car never went on road since last year as i had anti theft on it stuck on

so is this problem the Cat? the Innova code scaner i have all it shows is the EPA flashing but rest are good

like i have brand new exhaust from front to back and 2 new o2 sensor

how old is the first sensor? did you drive it a while to warm up the cat? do you see the cat monitor become ready on the monitor? what are the fuel trims

the sensors are both brand new last year i never got to use it

see what happened was i bought the upstream o2 sensor and entire exhaust system i pluged up the hole for the down stream o2 sensor and the car ran fine idlyin till it warmed up then it started miss firing and turned red hot and i had replaced the cat and it still did it then anti theft got stuck on and never got to work it till now

also garage told me last year that probably the thermostat sensor is malfunctiong and that it tells the computer its -40 out and pumps more fuel in it

but now with the new thermostat and the 2 02 sensors and me having the anti theft programmed out of the car it runs fine it just failed emmisions so thats why i thinking fromt cat being red hot last year it damaged cat?

and there is no cat monitor not that i see on the scan tool its a 97 so basiclly a 96 so it doesnt have those computer features

and fuel trim what is that? i also have the Hp tuners that i can plug to my laptop what would i read for that ??

the cat gets hot because its running rich. whether or not its permanent damage i dont know. so you have to check out the engine and see why. the temp on the scanner should be 195 ish when the engine is warmed up. if not the sensor is messed up. fuel trim is the difference between what the computer is running at for fueling and what it is supposed to run at. these all should be able to be seen by your scanner everything after 96 would. ive never used your scanner or hpt so i dont know exactly what you need to do.

ah ok well since the cat doesnt get hot anymore like red and doesnt miss fire i guessing either the 2nd 02 sensor or the temperature sending unit cured that problem but i thinking the cat is messed

can the scanner tools tells if a cat is working by the sensors on the car?

and what should the trim values be? ill check tommorow

If you look at the reading for the o2 sensors. The first one should be jumping around. The second one should stay some what steady it will jump a little but stay around the same. You need to have the vehicle at operating temp when you check to get accurate readings.

ok ya i notice that with both scanners is that the fuel trim u mean?

with the laptop while engine idling the o2 1 jumps up and down and 2nd one doesnt but when u gas it then the 2nd one jumps up and first one i think keeps jumpin up and down from memory i tested that a month ago

you get p0420 if the cat is bad. the o2 sensor in front tells the pcm what the engine is doing and the pcm uses that to adjust fuel.the rear only is there to compare to the front so the pcm can determine the state of the cat.

the catalyst monitor should go ready on your i/m monitor screen when the pcm tests it but you have to drive it a while a few times probably before it tests it.

the fuel trims in ideal world would be 0. but real world the older the vehicle and the state of tune up stuff and all makes it go from maybe 3 or 4 either way 5, or 6 probably acceptable. any more and something is on its way out.

well i know on the hand held reader the CAT light doesnt show up i guessing it doesnt have that option in a 97 but on my 2004 it shows up a cat light that its running so maybe didtn have those features in 1997 but could it be damage from turning red hot and now doesnt work right? but doesnt over heat now anyways

what else could i look for will the monitors tell me anything else to check for? would the EVA the evap i guess cause this high of issues? i know it flashes in the hand held

it has it but it takes a while of driving it before it runs the tests, after it runs the tests and passes then those are ready or must be on yours stop flashing