76 280 wont pass cal smog too rich!

[dastuffuwant]

more problems? so this isn't the original 1976 motor? this thing runs so good, but this is getting too confusing for me ( z novice) i better find a buyer.

[70 Cam Guy]

Did your car fail as a gross polluter? What gasses did it fail for? High CO? High HC?

Is it possible the exhaust manifold and exhaust were replaced from a later car? maybe the bung was welded on for an A/F gauge?

That intake looks like an earlier one (to my untrained eyes) because it lacks the EGR at the rear.

I don't think I'd give up on the car so easily. There are areas to look for a rich running condition (basic ignition components, coolant temp sensor/switch, fuel pressure, thermo time switch(?), etc)

[jwtaylor]

In California the seller is normally responsible for smog compliance/testing unless you took over the testing as part of the purchase. Not having it done by the seller can open a very large can of worms as it appears you are finding out.

I would check the engine/head numbers to find out what you have and then go form there to figure out what you need for smog controls.

[sblake01]

Andy, I was going by the fact the it has the solid fuel rail rather than the one with the two openings on top that are filled in with hoses. The solid fuel rail didn't show up until the 78 model year and was used until the end (83, 84 if you cound the Maxima). And then the 02 sensor didn't show up until 79. Also, the fact that there is no dashpot on the throttle body indicates that it's 79 or later. I see stuff capped of which also makes me think that the engine has been changed. Post the engine/head numbers as per jwtaylor's suggestion. That would help pinpoint what the year range is.

[mgood]

I don't know if this will help, it's mine from a stock never changed non Cali 1976 - 280Z car.

[dastuffuwant]

the hc's were like triple what they allow. i got this car from a military guy who had to deploy and didn't wanna store it. He had it for a yr and it was non-op status, so im responsible for the smog. i'll look for the engine #'s today and try to get them posted. i also read that someone disconnected the #5 injector and lowered the hc's. I really appreciate all your help, and will try whatever is suggested to lower the hc's as i really like this z and would hate to donate it for scrap. i have about $650 invested so far. (w/ my fingers crossed)

[conedodger]

The seller is by law required to give the buyer a current smog cert but if the buyer accepts it without, it becomes the buyers responsibility.

If it sat, you may have some gummed up injectors "spilling" fuel instead of squirting it. Clean, or have your injectors cleaned.

You should not have an O2 sensor on a '76. Perhaps you are thinking of the Cylinder Head Sensor which goes to the front of the engine? If this is disconnected, it is sending a resistance signal of infinity to the brain. The brain interprets this as an overheating situation and increases the injector time to full. That will cause unburned fuel which sniff as hydrocarbons at the tailpipe. Hook it up. Replace it if you can. Not sure if they are still available. I have a new one around here somewhere. Freakin' smog guy should have known that. If they are test only he might have been trying to get you to do it.

IIRC, California models had an EGR but 49 State did not? In any event if you do have one you may also be all coked up so take it off and wire brush it. Others may know better as the 280 efi engines have not been my thing in a while...

Edited February 1, 2010 by conedodger

[Pomorza]

Hey mate.

First off for my knowledge 76' 280z's did not come with O2 sensors that I know of. I own a 1/76 280z and it has no O2 sensors. I too have failed emissions and mine were 4 or 5 times the legal limit. First check things such as leaking injector(s), leaking cold start valve, bad thermotime switch, a malfunctioning or incorrect water temperature sensor, improperly adjusted or malfunctioning throttle position switch, a bad catalytic converter, improper fuel pressure

Secondly do a tune up on the car. Replace all the plugs with NGK's (B6ES I believe is the OE plug) wires rotor and cap. Also replace the air filter with a new one. Then do an oil change with the proper grade oil. Lastly make sure the timing is on where it needs to be.

I'm positive that the will at least decrease the amount of HC they your car releases. I would not unplug injectors to pass emissions. I've heard people have done it but it isn't really a good idea.

Hope that hleps

Jan

[70 Cam Guy]

Andy, I was going by the fact the it has the solid fuel rail rather than the one with the two openings on top that are filled in with hoses. The solid fuel rail didn't show up until the 78 model year and was used until the end (83, 84 if you cound the Maxima). And then the 02 sensor didn't show up until 79. Also, the fact that there is no dashpot on the throttle body indicates that it's 79 or later. I see stuff capped of which also makes me think that the engine has been changed. Post the engine/head numbers as per jwtaylor's suggestion. That would help pinpoint what the year range is.

I figured it was the details that I wouldn't recognize. Is there a way to ID which ECU came with the car? If it has the later computer, perhaps the retrofit was never finished

I was also suspecting leaking injectors at first but it's impossible to say. If you have access to a fuel pressure gauge for high pressure, you can watch the pressure after the engine is shut off. If the 280's are anything like newer cars, fuel pressure should not drop very quickly. Often there is even a spec for pressure drop over time. If the pressure falls too quickly, you can suspect leaking injectors

[sblake01]

Is there a way to ID which ECU came with the car? If it has the later computer, perhaps the retrofit was never finished

I have scans of the pinouts, year by year, but I doubt if the ECU would have been changed. In California, the emissions control setup has to be what the car originally came with not what the engine came out of. (I hope that makes sense)

[Powderkeg]

My 76 failed too when I first bought it. Very high HC's.

My mechanic did the following:

Replaced the catalytic converter

Adjusted the timing

Adjusted the Air/Fuel ratio

Total cost was about $230.00

Dave Ruiz

[dastuffuwant]

ok, i did new ngk's, new wires, new cap and rotor, changed oil, filter, air filter, and put injector cleaner. i drove it for 1hr and took it to the smog station and the readings were about the same 1 or 2 numbers difference, but still a gross polluter. he even let me disconnect the #5 injector it actually was worse thenwith it connected. i'll try the timing and air/fuel ratio and as for the cat the muffler shop next door said the cat wont change the number of hc that thing was putting out and that would be a waste of money.

Edited February 3, 2010 by dastuffuwant