blue_lateral
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If any of the smog stuff goes on this it all has to go. The mixture control and the timing advance is controlled by the computer. Quadajets were used on non-smog applications, but they were ones without the mixture control solenoid. HEI distributors were used on earlier cars, too, but they were ones that had weights, springs, and a vacuum diaphragm to control timing advance.
If this system thinks its broken enough, it will go into "limp home" mode. The carb will go full rich, and there will be no timing advance.
It is misleading to think of the stuff on this car as smog crap. It's main purpose is to control the mixture and timing very precisely, and in doing so make the car run good. Good emissions is a side benefit (though one that was really important to GM at the time). When this system came along in '81, it was a big, big improvement.
Probably all of the "smog equipment" that is there is necessary for the car to run right, except maybe the catalytic converter.
If I'm not mistaken, the air injection is used to light off the oxygen sensor. If you have a one-wire (or two wire) oxygen sensor this is almost certainly true.
The mixture on these is a "closed loop" feedback system. When you adjust it, the adjustments you make (when you are close) don't make any difference in the mixture. What you are doing is moving things to the center of the automatic adjustment range. The engine should be hot and in closed loop. There is a green connector on the harness running along the top of the engine. There is one wire in it. You can hook up a DVM here that has a 'duty cycle' function, or you can use a dwell meter (hook the second wire to ground). You want it moving back and forth around 50% duty cycle. If youre using a dwell meter, 50% duty cycle = 30 degrees on the 6 cylinder setting.
You can run the engine at 2500 or 3000 rpm or something. The cruise mixture is set by the mixture control solenoid height. There are holes in the top of the carb to get the little double-d wrench in. There are two adjustments, you probably saw them when you were inside the carb. One is the solenoid height, the other is a stop. One has threads that are exactly twice as coarse as the other. I cant remember which is which, but if you move the fine one 1/4 turn, you would also move the coarse one 1/8 turn. What you are trying to do is move the solenoid up or down while keeping the total travel the same. (I think it's 1/4 inch). When you get it right the duty cycle will be moving back and forth around 50% (or 30 degrees) and the travel will also be correct.
To set the idle, it is done the same way, but you use the idle jets. You start out with them set exactly the same, (I think this is 1.5 turns out). you make exactly the same change to both jets, and watch the meter. You also want 50% (30 degrees) at idle.
If the air injection and vacuum hoses are still all screwed up this probably wont help. I hate to be the bearer of bad news, but these cars typicallly run like complete crap unless all the engine control stuff is working.
Good luck
John
If this system thinks its broken enough, it will go into "limp home" mode. The carb will go full rich, and there will be no timing advance.
It is misleading to think of the stuff on this car as smog crap. It's main purpose is to control the mixture and timing very precisely, and in doing so make the car run good. Good emissions is a side benefit (though one that was really important to GM at the time). When this system came along in '81, it was a big, big improvement.
Probably all of the "smog equipment" that is there is necessary for the car to run right, except maybe the catalytic converter.
If I'm not mistaken, the air injection is used to light off the oxygen sensor. If you have a one-wire (or two wire) oxygen sensor this is almost certainly true.
The mixture on these is a "closed loop" feedback system. When you adjust it, the adjustments you make (when you are close) don't make any difference in the mixture. What you are doing is moving things to the center of the automatic adjustment range. The engine should be hot and in closed loop. There is a green connector on the harness running along the top of the engine. There is one wire in it. You can hook up a DVM here that has a 'duty cycle' function, or you can use a dwell meter (hook the second wire to ground). You want it moving back and forth around 50% duty cycle. If youre using a dwell meter, 50% duty cycle = 30 degrees on the 6 cylinder setting.
You can run the engine at 2500 or 3000 rpm or something. The cruise mixture is set by the mixture control solenoid height. There are holes in the top of the carb to get the little double-d wrench in. There are two adjustments, you probably saw them when you were inside the carb. One is the solenoid height, the other is a stop. One has threads that are exactly twice as coarse as the other. I cant remember which is which, but if you move the fine one 1/4 turn, you would also move the coarse one 1/8 turn. What you are trying to do is move the solenoid up or down while keeping the total travel the same. (I think it's 1/4 inch). When you get it right the duty cycle will be moving back and forth around 50% (or 30 degrees) and the travel will also be correct.
To set the idle, it is done the same way, but you use the idle jets. You start out with them set exactly the same, (I think this is 1.5 turns out). you make exactly the same change to both jets, and watch the meter. You also want 50% (30 degrees) at idle.
If the air injection and vacuum hoses are still all screwed up this probably wont help. I hate to be the bearer of bad news, but these cars typicallly run like complete crap unless all the engine control stuff is working.
Good luck
John
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