will not pass smog!!!

[xkeithx]

please excuse me if this information is somehwere else on the board, becuse ive been looking for the past few weeks and cant seem to come up with any solutions. i have a 1978 280z thats fuel injected, its a 5 speed, and it will not pass smog. i just took it in today and the HC i ibelieve it was was around 600-800. and i think it needs to be somewhere around 100 or less, im really not sure. im not a smog expert. but he said that number is way high, and whats happening is the gas isnt getting burned for some reason, and its just going out into the emissions. what can i do to get this number down, or are there any tricks like things i can unplug to make the car just get past smog? ive been driving the car with my temporary registration for the past month, and put about 2000 miles on it, and noticed that i get about 20 miles to the gallon. i used a can of stp fuel injector cleaner in the second tank of gas, and i put some fuel system cleaner in it recently. is there a can of anything tht i can buy that i can put in the tank that might help me pass smog?? one thing the smog guy mentioned was the pcv valve, he said when you rev the engine the valve is supposed to close, but for some reason it doesnt move. you can put your finger under it and move it manually, but for some reason the vacuum lines arent working i guess. he also said there could be a problem with the AFM, but is there nything else i could just fix or do to the car to get it to pass? i dont wnat to have to take it in somewhre and spend an arm and a leg to get my car to pass smog. i live in san francisco, CA. if anyone lives around this area and knows a good mechanic i could take it to, or some sort of datsun experts that live around here, that would me much appreciated. thanks so much!!

[Tourniqet]

You forgot the last three letter acronym, EGR valve. This is the exhaust gas recycling valve. I think it is supposed to recycle unused exhaust gas (mixture still unburned). If you get crappy gas mileage this might be it. I dont know how to check it, but I know it is probobly there... Good luck

[jlc280Z]

Check the EFI water temp sensor, mounted on the thermostat housing, check that it is connected, check for corrosion on the connectors. PCV is cheap, replace it. EGR valve could be stuck.

If you have the service manual, (highly recommended!) you can perform the tests indicated for the symptoms you have.

GOOD LUCK....

[xkeithx]

well i remember when i got it smogged the guy unplugged the egr valve vacuum hose and tested it, and he said there wasnt any vacuum. and he manually opened the egr valve and it made the engine run really rough, i dont know if that means anything. but what is the thing called that the vacuum line to the egr valve is connected to? its something that screws into the intake manifold, he said that could be faulty but i dont remember what its called.

[owenk]

Does a 78 have a "cat" ? If so it may be shot. I have 92 Saturn and it did not pass smog due the HC being very high ~900. I installed a new "cat" and it dropped it way below passing. Also if your smog pump is not providing enough fresh air your "cat" may not be able "clean" the exhaust stream.

FYI

The purpose of the EGR valve is to recycle exhaust gases into the intake stream which results in cooler combustion temps which results in less NOx. So unless the NOx readings are high it is unlikely that the EGR has a problem.

PS I got a “cat” at Kragen for $79.

Good Luck