Howdy all, Just got back from a year sitting over in Afghanistan and trying to get my car registered. Took it in for the smog this morning and failed miserably (see pic). Looking to see if anyone might have an idea of what would be causing the HC/CO to be so high? The other highlighted fail on there is the timing, it was off a bit.

86 GT-S with a bone stock 4AG.

Two years ago when tested it was
HC - 41 @ 15mph, 18 @ 25mph
CO - .02 @ 15mph, .02 @ 25mph

Head gasket and timing belt changed little over a year ago with new cap, rotor, and plugs as well. Runs like a champ.

Any suggestions greatly appreciated.

It doesn't look like a miserable fail... that would be WAAAAY off......

timing off... and you did the head gasket... I'd say check cam timing, and check ignition timing... set both to stock as per the FSM... Check cap,rotor, wires, and plugs, replace filters, and change the oil.... Drive it hard and get it hot... re-check.

Another solution pay a little extra and make that baby pass lol

Post the entire results not just the failures. I'm talking CO2 O2 etc...

Also, it looks like your EGR is blocked, or one of the charcoal canisters needs to be changed. Not sure if that would spike your HC and CO so high.

VitriumGTS wrote:Post the entire results not just the failures. I'm talking CO2 O2 etc...

CO2
11.16 @ 15, 11.40 @ 25

O2
.10 @ 15, .01 @25

NO
263 @ 15, 234 @ 25

Your cat is dead or the car wasn't properly warmed up at all. Probably a huge fuel leak somewhere too. I'm betting leaking injector/cold start but check to see if the cat is even there.

Do you have any codes? Maybe a code 11 (misaligned tps?). Make sure that is cleared first before retiming the distributor.

Just a quick close out on this one.

The culprit was a bad TPS. It was sending a constant WOT signal and dumping fuel causing it to run way rich. New TPS from Autozone and re-timed and the CO dropped from 5.49 to .07...passed with ease .

Appreciate the assistance.

My car failed smog the first time.

Check your timing, do a tune up with new spark plugs (pay a little extra for ones with a "hotter" spark), and get a new oxygen sensor.

That did it for me

Good luck!

bad tps leading to fuel dump? Damn, I was pretty close! lol

good post! Mine seems to be running way rich too. O2 levels were super low like urs. I still need to clean out EGR and tighten exhaust mani cuz theres a leak, but I think I'll try a new TPS also.....