81 emissions
09-19-2009, 11:46 AM
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Location: Flagstaff, AZ
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The '81 is going to be a lot different from my '80. Basically all I have connected on my 1980 stock carburetor is the distributor advance, and the anti-backfire valve in the intake manifold. I converted the choke to a manual choke (needed a new thermostatic coil so I didn't want to spend the bread), so I have even disconnected the vacuum pulloff.
I would generally advise this:
First get a vacuum diagram that reflects the equipment that you have. Then eliminate all hoses and rebuild your own diagram in a logical sequence. For example:
1) I first tore everything off the truck, meticulously plugged it up and acquired a decent quantity (about 8 feet) of new vacuum hose.
2) I obvioiusly wanted the vacuum advance distributor so I hooked that up.
3) I started the truck. It would run for a few minutes and then as soon as it warmed up it would die. This points to a thermostatically controlled vacuum device.
4) Looks like the vacuum hose that goes to the thermostatic vacuum valve on the side of the intake manifold also goes to the anti-backfire valve in the intake manifold. So I routed those hoses (using new hose). Viola! The truck ran great.q
EGR is one of those things where you have to consider its usefulness. Some cars will have trouble when you block off the EGR valve. EGR is an emissions control device but few people realize how it also works to decrease the oxygen level in your combustion chamber. There are occasions where disabling your EGR system may cause excessive knocking "pinging" which can cause damage to your engine.
That being said, my EGR valve was so badly plugged with carbon I decided to take the chance. It is now plugged up with epoxy and steel plate, never to be used again. I now run regular 87 octane fuel through it and tried lugging it in a few gears to see if I could get it to knock. No knocking, so the EGR system remains off.
The only thing my '80 still has is its emissions control computer. I think it might control some of the ignition timing functions on the truck so I am scared to just unplug it. Since I eventually plan on converting the truck to an early model Supra engine I figure I will leave it in place - since the truck is really running quite well now anyway....
If your truck is "blessed" with A/C as mine originally was (old owners scrapped it a long time ago evidently), then you will have to figure out the A/C idle up controls to avoid making your truck run like crap when sitting at a traffic light. Either that or wire in a switch to contorl your A/C clutch so you can manually disable it when you're idling in traffic.
I would generally advise this:
First get a vacuum diagram that reflects the equipment that you have. Then eliminate all hoses and rebuild your own diagram in a logical sequence. For example:
1) I first tore everything off the truck, meticulously plugged it up and acquired a decent quantity (about 8 feet) of new vacuum hose.
2) I obvioiusly wanted the vacuum advance distributor so I hooked that up.
3) I started the truck. It would run for a few minutes and then as soon as it warmed up it would die. This points to a thermostatically controlled vacuum device.
4) Looks like the vacuum hose that goes to the thermostatic vacuum valve on the side of the intake manifold also goes to the anti-backfire valve in the intake manifold. So I routed those hoses (using new hose). Viola! The truck ran great.q
EGR is one of those things where you have to consider its usefulness. Some cars will have trouble when you block off the EGR valve. EGR is an emissions control device but few people realize how it also works to decrease the oxygen level in your combustion chamber. There are occasions where disabling your EGR system may cause excessive knocking "pinging" which can cause damage to your engine.
That being said, my EGR valve was so badly plugged with carbon I decided to take the chance. It is now plugged up with epoxy and steel plate, never to be used again. I now run regular 87 octane fuel through it and tried lugging it in a few gears to see if I could get it to knock. No knocking, so the EGR system remains off.
The only thing my '80 still has is its emissions control computer. I think it might control some of the ignition timing functions on the truck so I am scared to just unplug it. Since I eventually plan on converting the truck to an early model Supra engine I figure I will leave it in place - since the truck is really running quite well now anyway....
If your truck is "blessed" with A/C as mine originally was (old owners scrapped it a long time ago evidently), then you will have to figure out the A/C idle up controls to avoid making your truck run like crap when sitting at a traffic light. Either that or wire in a switch to contorl your A/C clutch so you can manually disable it when you're idling in traffic.
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