Hy I have a 91 camry v-6 with 195,000 miles.Have owned since 40,000 miles and always passed emmisions with no problem till now.They say I'm putting out too high of hydrocarbons unburnt fuel.I checked many things plugs,timing,pcv,valve,oil change,air filter.Everything looks good plugs are burning clean fuel mileage is the same it's always been at about 25 mpg.The only thing that has changed is that I had to put a new cat convertor on about 6,000 miles ago and this is the 1st test I have taken since then and at this point I have failed 3 times even after putting octane booster,G.O.P.,and and gas line anti freeze,seafoam injector cleaner in the gas tank.I did not ever adjust the valves and did no compression test on the cylinders because the car runs good.It has a slightly rough idle but never stalls or anything and idles where it should at about 600 to 700 rpm's.I'm really thinking that they gave me a universal convertor that is not as good as my original one and this is my problem.I am at my wits end in trying to pass this test does anyone have any thoughts on the matter? Thank-You

 

i would chase the running rough condition..did you check your igntion wires...also tap on the egr to see ifits stuck open. tapping may release the punger idle should be smoother. ....check your compression...see what you O2 sensor is reading , use the data link connector and a volt meter, connect O21 to E1..your meter should fluctuate from 0.1volt to 0.9volt 8 times in 10sec at normal operating temp and 3000rpm ...there's a test to see if you cat is operating normaly.. you need to check the temperture of the gas fume entering the cat with an inferred tempgun..and then do the same exiting the cat..the exiting flumes should be 200 deg or over (depending on cat).. if not the cat isn't hot enough....good luck..give me a heads up on what you find.

 

I had the same issue with an 89 camry back in the day and it ended up being the cat and O2 sensor.