Hope no ones offended, but I've been reading, some times daily, on here for almost 2 years now. And Ive accomplished quite a bit just by reading and searching, untill now.

As stated, smog pump and EGR have been retained after I finished, or cleaned up what PO had gotten himself into. Which left me with a remanned carb, ebay find, heat choke only, a DUI dizzy(was a bargain from friend). Computer harness and all that went with it is removed.
Its a 1986 F150 300 I6, 4 Spd manual 2WD. It runs, but could run better, I'm workin on it.

My question(S)...

Aside from idle, is there any other time my air pump is activated? What RPM does it divert air to the EGR, or purge?

Do I need the pump hooked up to the EGR or can I pump to the CAT only?
Since the pump increases the temp of the CAT, I don't imagine its safe to just hook it up and let it pump all the time.

I fully understand the pump and its relation to the cat, I understand the purpose of the EGR, I can't seem to grasp the purpose of pumping fresh air into the EGR block. Or am I missing something?

I can not pass emission testing with out the pump connected to the cat. The valve block is still there and working, hooked up vac line to feed the cat and passed with flying colors. (HC 21 and CO .28) With out the Pump, HC 834 CO 18.26. State allowed HC 400 CO 4.

If I know where in the curve the pump is supposed to pump to what, I can either control manualy, or come up with a way to make them automatic.


Thanks in advance!
And thank you for all the past help! This forum is a plethora of knowledge.

 

Welcome to FTE, I lurked for ~1 year before joining.

BTW I can't see the AIR pump being connected to the EGR, that doesn't sound right but I will let others who know more answer to that....

 

This is from autozone's site.

Most 1976-86 models are equipped with a Thermactor emission control system. The Thermactor emission control system makes use of a belt driven air pump to inject fresh air into the hot exhaust stream through the engine exhaust ports. The result is the extended burning of those fumes which were not completely ignited in the combustion chamber, and the subsequent reduction of the hydrocarbon and carbon monoxide content of the exhaust emissions into harmless carbon dioxide and water.

The Thermactor system is composed of the following components:

Air supply pump (belt driven)

Air control valves

Check valves

Air manifolds (internal or external)

Air supply tubes (on external manifolds only)



Air for the Thermactor system is cleaned by means of a centrifugal filter fan mounted on the air pump driveshaft. The air filter does not require a replaceable element.

To prevent excessive pressure, the air pump is equipped with a pressure relief valve which uses a replaceable plastic plug to control the pressure setting.

The pump supplies air under pressure, into the exhaust system thus lowering the exhaust emissions due to combustion. The belt driven air pump takes air in through an impeller-type centrifugal air filter fan, thus eliminating the need for a separate air filter. Dust and dirt particles cannot enter the pump because these heavier than air contaminants are thrown from the air intake by centrifugal force. The Thermactor air pump has sealed bearings which are lubricated for the life of the unit, and preset rotor vane and bearing clearances, which do not require any periodic adjustments.

The air supply from the pump is controlled by the air by-pass valve, sometimes called a dump valve. During deceleration, the air bypass valve opens, momentarily diverting the air supply through a silencer and into the atmosphere, thus preventing backfires within the exhaust system.

A check valve is incorporated in the air inlet side of the air manifolds. Its purpose is to prevent exhaust gases from backing up into the Thermactor system. This valve is especially important in the event of drive belt failure, and during deceleration, when the air by-pass valve is dumping the air supply.

The air manifolds and air supply tubes channel the air from the Thermactor air pump into the exhaust ports of each cylinder, thus completing the cycle of the Thermactor system.





The Air Supply Control Valve is used in the thermactor system, to direct air pump output to the exhaust manifold or downstream to the catalyst system depending upon the engine control strategy.

Start the engine and allow to idle. Disconnect the inlet hose at the valve.

Verify that air flow is being supplied to the inlet by disconnecting the air supply hose at the inlet.

Verify the presence of air flow with the engine at 1500 rpm. Reconnect the air supply hose at the valve inlet.

Disconnect the air supply hoses at outlets "A'' and "B'' as shown in the appropriate illustration.

Remove the vacuum line at the nipple.

Accelerate the engine at 1500 rpm. Air flow should be heard and felt at outlet "B'' with little or no air flow at outlet "A''.

With the engine at 1500 rpm, connect a direct vacuum line from any manifold vacuum fitting to the air control valve vacuum nipple. Air flow should be heard and felt at outlet "A'' with little or no air flow at outlet "B''.

Restore all connections. If the desired conditions above are not met, replace the air control valve.

Thermactor Idle Vacuum (TIV) Valve

See Figure 6

The Thermactor Idle Vacuum (TIV) valve vents the vacuum signal to the atmosphere when a preset manifold vacuum or pressure is exceeded. It is used to divert thermactor air flow during extended idle conditions to limit exhaust temperature.

 

The only thing the thermactor system and EGR have in common is the vacuum line from the two port valve that opens once the engine starts to warm up and is driven off the EGR port of the carb. A spart or ported vacuum source can also be used. This port gets a vacuum signal at cruise and mild acceleration.

There should be a throttle valve solenoid that's connects manifold vacuum to the air bypass valve to open it on decel.

Manifold vacuum is metered to the air control valve via the EGR load control valve. I'm guessing that's done because it would need a stronger signal than you can get from the EGR port directly but that's only a guess. I also assume it's an A-B switch that defaults to one position and when the EGR circuit is active it switches the ACV to the second position. Again, just a guess. That system isn't functioning on my truck due to the PO's hack work and since I don't have testing I'm not hooking it back up.

 

Thanks Guys!

Love the read from autozone, wish I had found that earlier.

I'll get pics up as soon as I can, but what I have under my hood looks nothing like either diagram.
To explain better...

outlet on my pump runs to a square plastic block, from that block, one hose goes to my cat, and another hose goes to a short piece of hard pipe screwed into the EGR block.(chunk of metal between carb and intake manifold)
Now, attatched to that plastic block the hoses connect to are two vacuum actuators I'm guessin. They look just like the vacuum switch that opens and closes my EGR. Each has a nipple to hook up vacuum. The whole system functions as described in "text" from autozone when I apply vacuum accordingly.

The tube running to the EGR is infact just a passage to the exhaust manifold, and is pumped fresh air at deceleration to prevent backfire. I wondered how it got there, I was sure I was missing a piece, and was going to address that after I figured out what was connected to my EGR.
Got it!
Thanks!!

So....as there are no solenoids, sensors(aside from the dash), wires, ECM what so ever, and no backfiring issues. I'd like to have the system pump air at idle, and just purge to the atmosphere at anything above an idle.
At idle the exhaust can be a bit strong, though still runing on the rich side of things...

Idealy, I'd love to have the pump deliver air at say 1200 rpm, and divert air at anything above that.

I thought of using an old tach with a shift light, not sure the model guys, its burried in a box, but is from the shelf at...yup...autozone.
Anyway, it also can be set for the light to come on and stay on once you hit your desired rev limit.
Don't know if I can set it as low as 1200 rpm, but no reason why the input to that light can't flip a switch right??
Or am I nuts....

And if thats logical...does a switch like this exist? Would have to be something like this for pneumatics, hydraulics ect. right??

Thanks guys for your posts, and clearing up my confusion on the EGR, decel stuff.

Sorry, didn't look at the second diagram carefully since it was for V8 with dual cats, however thats the bypass/control valve currently installed in my truck...

 

Posting pictures is the best thing to do.......

User Gallery & Picture Display Help - Ford Truck Enthusiasts Forums

 

Is there a reason why you would not want it to work like the factory has it? It doesn't really hurt anything, just a little bit of horsepower to spin the pump.

 

I'd love for it to!! And thats my goal, minus an ECU, and its associated components.

I want the diverter to do what its supposed to do, when its supposed to do it. However, I don't want to purchase/re-install all the components just to have my air pump on occasion.

If I just apply vacuum to one or the other, they will remain open, not sure what constant flow to exhaust manifold would do, but I'm sure a constant flow of air to the cat would surely cook it in short time.