Failed smog test

[Erick]

Hey guys so I just smoged my 78' 280z. It failed the guy told me it was running rich everything else is ok. Idk what it could be I was thinking maybe a bad sensor? I'll post a picture of the results and idk you guys tell me what I should look at and what I might need to replace. The car starts and idles around 1000-1200 rpms than after it warms it settles down to 700-800. I did notice when I change gears maybe from 2 to 3 it does a little extra push on the gas. Idk what do you guys think?

[Zed Head]

What is the state of the engine at this point?  When did it last have a tune-up, including valve lash adjustment?  Last oil change?  Did you just buy it?  How often was/is it driven?

The paperwork says "Fail" on ignition timing.  What's that about and what is initial timing?  Does the vacuum advance work?

Lots of possibilities.  Need more info than needs an extra push on the gas when shifting gears.  A lot more.

[rcb280z]

Agree with ZH, more info is needed.

Your HC's are WAY out of wack. And the CO's are a little high. It's been my experience that, if the engine is in good shape, by the time you get the CO's in check it may not be enough to lower HC's. I've seen it increase as a matter of fact if the vacuum advance isn't working and the engine and catalytic converter are tired. 

So what is the timing at, do you know? 

I had high HC's (800-900 IIRC) and replaced the cat. It did the trick. But everything else was in order. If you need a cat make sure its CARB approved or you'll fail again.

There are so many things that can make these cars fail emissions. You have your work cut out for you and if you don't feel comfortable doing any of the work find a mechanic that knows these cars. Check with your local Zcar club for recommendations. 

Edited August 28, 2018 by rcb280z

[charliekwin]

I had similar numbers when I got mine. There were a couple easily identified and fixed problems, but ultimately it was the throttle valve switch that was responsible in my case (https://www.classiczcars.com/forums/topic/51531-sanity-check-on-280z-fi-tests/). I didn't find it until I ran through the tests in the EFI bible, which is where I should've started in the first place. Only takes a few minutes to go through them all. Do that.