Fail Emission, bad catalyc???

97GTSTANG

Founding Member
May 25, 2000
852
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17
Virginia
I have a bassani x with cats and i failed emission, and they are saying it sthe cats. i still have the stock cats but it has been in the back yard for about 3 months and it had been rained on and got a little dusty. Do you all think its effective or damaage? Maybe water got down the cats. Any ideas if they are still good so i can swap them out?
 
I have a steeda timing adjuster, if i drop the timing down to 6degrees will it help me pass the NOx part of the emission? I was told it will help me pass emissions. ANy suggestions?
 
The emission test was ran at 10degrees and with premium gas. will that make a difference or should i get regular gas and drop timing down to 6 or 8degrees. Will it really make the NOx readin drop from 765 to 605?
 
whoa whoa, you are looking at the wrong area. change your EGR. the EGR is what controls NOx, have that checked out first. i do smog checks all day. take off your EGR and see if the passageway is clogged. also check to see if it works. if its like any other EGR, take off the vacuum line and hook up a vacuum gauge and apply vacuum to it and see if the idle drops to almost a stall. if it doesnt its a bad valve. then hook up the vacuum gauge to the vacuum line and rev the motor, there should be a change in vacuum. if not then the passageway is blocked.
 
Thanks for clearing that up. so u dont think its the catalytic converters? I will check the EGR as you suggested. Is there a way to check the catalytic converters?

bdcardinal said:
whoa whoa, you are looking at the wrong area. change your EGR. the EGR is what controls NOx, have that checked out first. i do smog checks all day. take off your EGR and see if the passageway is clogged. also check to see if it works. if its like any other EGR, take off the vacuum line and hook up a vacuum gauge and apply vacuum to it and see if the idle drops to almost a stall. if it doesnt its a bad valve. then hook up the vacuum gauge to the vacuum line and rev the motor, there should be a change in vacuum. if not then the passageway is blocked.
 
if you just failed for NOx i would look at the EGR first. thats the principle emissions component for the reduction of NOx. yes the cats will have an effect. when have you last done a good tuneup. like new plugs, using a throttle body cleaner with something along the lines of seafoam to clear out the intake passages? those will help. i would tend to think the EGR is bad.
 
I got new plugs put in by the shop just 3 months ago after they did the headswap. I am not sure what plugs they put or what its gapped at, but i dont know if that will make adifference. one of the mechanic i know said i should retart the timing and that will hlep me pass. Not sure if the NOx will drop that much though just by lowering the timing. He is going to check the EGR for me on monday, hopefully its just the EGR and nothing to do with the cats.