Technical questions!
I've read the postings somewhat related to this and want to find out what to check first. Automatic tranny car failed on CO% & HC on the rollers at "low speed" ~1600 rpm only, CO std is .76%, car had 5.34. HC std is 136, car had 797! Passed emissions on "high speed"~2500 rpm. Remember, this is an AT car.

The archives and related postings offer these as suggestions in order of priority (I DO NOT want to use any fuel additives!):

1. air control (primary and secondary) valves/selenoids on inner upper intake manifold-how to test outputs?
2. air pump (checked and clutch turning, shuts on and off due to AT load and accelleration up to 3000 rpm), maybe not pumping? Can they wear out but still turn?
3. catalitic converter How do you check this?
4. Oxygen sensor-how do you check it if no trouble code?
5. water temp sensor-(not probable)-how do you check this if no trouble code?
6. AT shift solenoids (hope not)-control ecu


Marc

 

How many miles are on the car?
Any modifications?
When did you last change your oil and spark plugs?
Was the car warmed up before you tested it? If so, for how long?

-s-

 

If you have over 50k and the O2 sensor has never been replaced that would be the first place I'd start. (I'm assuming the car had good spark plugs, etc.)

On most cars, the bad cat converters I've seen involve a substrate that's broken up. If you bang a balled up fist on the converter shell and can hear rattling inside, that usually indicates it has gone bad........although if it's the precat that's broken up it possible the pieces have gone downstream and lodged in the main converter.

 

I had the same problem with smog. have the tech test the car 0-15 mph in first gear then shift to second gear for the 15-25 mph test and leave it in second for the rest of the test. bet you will pass just fine. the autos go into overdrive quickly and the ecu seems to dump a lot of fuel and get rich in overdrive . and don't let him boost the car during the test you will fail for sure.
Jeff