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My car is having a hard time passing smog.. It goes like this..
Everything the same as the day I bought it except the throttle body.. I drove it around for a half hour..
took it to the smog place and the car blew the test at idle

1st try numbers:
@900 rpm
idle speed test(no revving)
max allowed: HC 220 ppm
mazda: HC 331 ppm
Result: FAILED

I figured the idle was too high.. went home and tightened the air adjust screw while the TEN+GND jumped had the idle settled further down

went back next day

@780 rpm according to the guys inductor
idle speed test
mazda: 301 ppm

I figured I was on to something since lowering the idle made the HC lower.
Did some research and found HC is basically unburned fuel.
All smog tip websites suggest ignition parts with tune up..
No big deal since I don't the history of the car.. I went ahead and timed the car 10* btdc
changed the spark plugs and ignition rotor. cap looked alright.
changed the oil. Car sounds good HLA tick when cold is gone..
I drove the car about 30 minutes..

3rd try

@670 rpm according the machine
idle speed test
mazda: 449 ppm
WORSE! The car is running better and quieter. Has more power than when I first got and I can't get this damn thing to pass.

You need pre cat testing with a gas anylizer to confirm the state of health of your cat...

There is a good chance though your tps is out of adjustment... This won't allow the car to enter proper fuel control at idle... it causes high hc and usually Co readings...

You need to set your idle back to stock properly and recheck cat health and tps adjustment

woops forgot to mention I adjusted the TPS with a feeler. All within spec per Daninski's instruction.. so throw a new cat on?

zerialz wrote:woops forgot to mention I adjusted the TPS with a feeler. All within spec per Daninski's instruction.. so throw a new cat on?

Can't tell you the ccat is dead with out proper testing...you can keep throwing parts at it or you can have someone pproperly diagnose it...

it's possible the thermostat is stuck open and the car isn't warming up causing it to stay in open loop... or even a bad coolant temp sensor. ..could be burning oil.. but once again you need proper pre cat readings with a gas anilizer. ...

I guess I'll take it to guys I brought my probes to.. whenever I got tired of messing with them..

It was the cat.

how do you know it was the cat?
Did you have it tested?

I'd hate for you to have to replace a cat again next year

It was tested with a new cat and passed instantly. the pre-existing cat looked marginally aged but, the car did come with a throttle body issue.. I'm changing to royal purple next interval with new ngk wires.. in the next week or two I'll change the IM and VC gaskets..