Engine restricting emission removal

[BenM]

This section on Wikipedia is pretty much the straight poop as I understand it on the way our cat is set up.

That's why, for instance, an engine running rich with upstream air injection stuck on will cause a cat to overheat. Too much fuel.

[rohnk]

That article does give a good understanding of how they operate.

OK, I guess I will get back to it for a little while.

[carnuck]

If it is a feedback carb, there is a stepper motor on the back side of the carb, which has a square 5 wire connector going into it. Also there is a TPS which is just on the passenger side, and has 3 wires going into it. If the carb has been swapped, those won't be on a non-feedback carb, but the harnesses should still be there.

Also,are there 3 vacuum solenoids on top the valve cover? Are there 3 vacuum switches on the passenger side fender across from the distributor? If yes, your car definitely had a feedback carb at one point.

No stepper or stepper plug. None on the emission diagram when I glanced at it too. Tag says 1981 CA emissions certified or words to that effect (Whoa! Wonder if they meant Canada?)

[BenM]

No stepper or stepper plug. None on the emission diagram when I glanced at it too. Tag says 1981 CA emissions certified or words to that effect (Whoa! Wonder if they meant Canada?)

It's definitely California, however you can't have air injection and a feedback carb on the same vehicle. The computer's feedback functionality would be disabled by the air dilution. (It's conceptually possible, I bet it has been done.)

[rohnk]

BenM, I beg to differ. I removed a feedback carb and the dual air injection setup on my vehicle. Still in process.

[ammachine390]

Dual air injection was used on the 82 models which used the feedback carbs. And 81 Concords/Spirits also have dual air injection with a feedback carb as well. Mine still has it. The computer routes the the air from the air pump to the catalytic converter when the engine is warm. If it injected it into the exhaust manifold, it would completely throw off the O2 sensor. Air was only directed upstream during open loop operation.

[BenM]

BenM, I beg to differ. I removed a feedback carb and the dual air injection setup on my vehicle. Still in process.

Yeah, you're right and I should have known that; my old parts car was an 82. It seemed like such a complex work-around in my head when I was thinking about it yesterday.

I just checked my feedback system supplement. It doesn't have a diagram of the hoses, though. Does it still use the injection manifold in the exhaust manifold over the exhaust valves?

[ammachine390]

It has the air injection manifold still. But the vacuum solenoid on the far passenger side on top of the valve cover controls a valve that either directs air into the manfiold, or into the catalytic converter. When there is no vacuum allowed to the valve, air is directed upstream, when the solenoid turns off, vacuum passes through the solenoid to air valve, and air is directed downstream.

[rohnk]

I don't think the computer controlled all of this switching. There are vaccuum lines that go from the CTO to the air diverter and downstream feed to the cat. When the engine gets hot, the CTO opens to alow vaccuum pressure to switch the diverter on/off. The oxygen sensor would measure the amount of air and the computer would richen or lean the mixture based on those readings.

There is no wiring from the ECO to the air pump or any of the valves on my 82. All controlled by vaccuum and temp sensors.

[ammachine390]

I'm sorry but you are incorrect. While all the valves for the air injection systems are all mechanical vacuum valves, the computer does play a large part in it, because the vacuum for those mechanical valves is controlled by the ECM. The CTO valve does not do anything for the air injection system.



In the photo, the solenoids marked "upstream solenoid" and "divert solenoid" are electrical solenoids controlled by the ECM. They are connected to vacuum hoses, when the solenoid is energized by the computer, vacuum does not flow. When they are not energized by the computer, vacuum is allowed to flow. So on a cold startup, the ECM will energize the upstream solenoid, vacuum cannot pass the valve, and the mechanical air valve directs air to the air injection manifold. When the car warms up, the computer de-energizes the solenoid, and vacuum can then pass, which flows to the mechanical air valve, and directs the air to the catalytic converter.

All together, in 1982, the computer did 4 things: control air/fuel mixture, control ignition timing, control air injection solenoids, and controlled idle speed.

[rohnk]

Ok, I give. You are correct. I totally forgot about the two solenoids. I remember taking them out as part of the vac system on the passenger firewall IIRC.

Thanks for clarifying that. This is becoming a great thread for learning about the emissions and vaccuum systems.

[kajsdf]

emissions is extremely simple if you install the motorcraft, virtually all vacuum lines except carb -> distributor, 4x4, and cruise can go.  cto can be plugged, and the line to the egr valve can simply be removed if it was functioning correctly before being disconnected, since it is naturally closed.  the pulse air lines going to the cat can be plugged however you wish (i have mine plugged right before the metal lines going to the cat leave the engine bay since it was easier than welding shut)

then you can hook up carb bowl vent to the canister, and fuel tank to canister, and you're pretty much done.

you can also remove a ton of wiring and the computer itself since all sensors will be inactive without the feedback carb.  i took out mine and about half the wiring harness came with it.

[rohnk]

I'm removing the EGR and CTO as well. I want to remove the computer at some point. I will save that project for another day.

[carguy87]

Be sure if you are to retain your A/C that you hook that vacuum line back up to your heater controls as well, not needed with the upgraded carb though.

[kajsdf]

forgot to mention the computer is hidden beneath the passenger side wall trim panel under the dash. you'll know it when you see it...