Need explanation of code 44,94

kdog_x · Aug 3, 2004

I fixed some broken vacuum lines going to my emmisions parts, now I'm getting code 44 and code 94. I don't have the steel lines that go to the back of the heads hooked up, but everything else is fine.

It says that these codes mean left thermactor system inoperative and same for the right. Is that the steel lines I removed or something else?

axeman · Aug 3, 2004

i'm almost sure it's because of the lines. those codes have something to do with the smog pump and lines your missing.

jrichker · Aug 3, 2004

Pete & Repeat...

Codes 94 & 44 - AIR system inoperative - Air Injection
Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source any power to actuators, relays or injectors, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

kdog_x · Aug 3, 2004

I don't have any way to apply vacuum to the valves, but I did do some checking. There was suction on one of the lines coming from the passenger side wheel well -- so I'm assuming it has power. And only one line should have suction at a time, right? There was air coming out the back of the smog pump, so I think that valve works (or it always sends it to the second valve). And there was also air going down to the catalytic converters, so the second control valve should be working (not sure if it works as far as kicking air out towards the heads).

I was just wondering why I got a code for left side thermactor system and right side thermactor system not working. By left and right, do they mean the lines running to the back of the left head and right head -- or is it just a general code that means there's a problem somewhere in the system.

jrichker · Aug 4, 2004

kdog_x said:
I don't have any way to apply vacuum to the valves, but I did do some checking. There was suction on one of the lines coming from the passenger side wheel well -- so I'm assuming it has power. And only one line should have suction at a time, right? There was air coming out the back of the smog pump, so I think that valve works (or it always sends it to the second valve). And there was also air going down to the catalytic converters, so the second control valve should be working (not sure if it works as far as kicking air out towards the heads).

I was just wondering why I got a code for left side thermactor system and right side thermactor system not working. By left and right, do they mean the lines running to the back of the left head and right head -- or is it just a general code that means there's a problem somewhere in the system.

Use engine vacuum to do the testing.

The first valve will cause the smog pump to pass it's output to the next valve or vent it overboard. The first valve vents the air to the atmosphere at WOT, saving power. At normal power settings, it passes air back the the second valve.

The second valve sends the air to the heads when the engine is cold and to the car converters when the engine is warm.

The right & left codes when used on 5.0 Mustangs, mean that the last diverter valve isn't switching the output from the heads to the cats.

kdog_x · Aug 4, 2004

jrichker said:
The right & left codes when used on 5.0 Mustangs, mean that the last diverter valve isn't switching the output from the heads to the cats.

Thanks, thats what I was trying to figure out. I used the engine vacuum to check if the valve was working, apparantly it kicks air out to the cats when it has no vacuum on that second valve. I put vacuum on it and it does switch toward the heads, but since I dont have the steel piping there it kicks it out into the engine bay. I'm guessing it checks the o2 sensors for a change in air during the KOER test, and since it didnt find extra air thats probably the reason it tripped this code.

Since I dont have the steel lines maybe I should just plug that second vacuum line. Kicking the extra air down to the cats when it's cold shouldn't have any adverse effects, right? This also might explain why it always catches and then dies every time I start it up in the morning.

Zero_chance · Aug 4, 2004

KDog, I have the same exact codes and same exact problems with my 5.0
Every morning when I start it it dies a couple times unless I hold it at 1500 - 2500 RPMs. Im poking around at mine too, let me know if you ever solve it.

kdog_x · Aug 4, 2004

Do you have those steel lines running to the back of the heads? I think the computer probably makes it run a little richer to compensate for the extra air it's supposed to get through those lines, it only does it when the engine is cold (same time it's supposed to be getting extra air). I can't think of any way it could be fixed aside from hooking the lines back up though.

Hope it doesn't kill my cats, I need them for at least 3 more days!

jrichker · Aug 4, 2004

Here are some general statments for the benefit of those who are trying to re-connect their smog pump plumbing...

If you are missing the pipe that goes to the back of the heads, leave the output uncapped & let the air pressure vent to the engine compartment. Or you can play with the vacuum routing and make it pass air to the cats all the time.

If you are missing the pipe that goes to the cats, you probably won't pass smog testing.

Here's a tip for those who are missing the tube that goes to the cat converters. Get the check valve from the auto parts store. Then make a trip to Home Depot for some large copper tubing or steel electrical conduit. Match the check valve size up to the tubing or conduit as closly as possible. The copper tubing is easier to bend, but more expensive. Sand poured into the tube and then heating the tube makes it easier to bend. The sand will keep the tube from colapsing if it is right where you make the bend.

5.0guy · Aug 4, 2004

I have the pipe that goes to the back of the heads, but that's capped. can I just cap the back of the heads? I don't care about the smog pump, but I don't want to have it venting into the engine compartment because it sounds like one big exhaust leak. I did, however, notice that when I uncapped it, my rpms stuck at about 1200rpm and the revs would take a while to come down. so is this a vacuum leak, too?

Stang8URMPRT · Aug 4, 2004

You're whole smog system runs off the steel lines that connect to the back of the heads. That is where you get all your exhaust recirculation. Exhaust comes out of there and into the smog pump and to the egr. If you do not have the cross over lines that are on the back of the heads, it's like pulling the heart out of the smog system and it will never work correctly.

Nick

jrichker · Aug 4, 2004

Stang8URMPRT said:
You're whole smog system runs off the steel lines that connect to the back of the heads. That is where you get all your exhaust recirculation. Exhaust comes out of there and into the smog pump and to the egr. If you do not have the cross over lines that are on the back of the heads, it's like pulling the heart out of the smog system and it will never work correctly.

Nick

Good intentions but wrong theory...

The EGR & smog are two separate systems.

The EGR picks up exhaust gases from the center exhaust ports and passes it up to passages in the lower manifold. It goes to the upper manifold and then to the EGR valve. The computer regulates the suction on the EGR valve to supply the correct amount of exhaust gas according to the current conditions. The EGR closes at WOT (wide open throttle).

The smog pump or AIR (Air Injection Reaction) system uses a vane type pump to compress air.
The first valve will cause the smog pump to pass it's output to the next valve or vent it overboard. The first valve vents the air to the atmosphere at WOT, saving power. At normal power settings, it passes air back the the second valve.

The second valve sends the air to the heads when the engine is cold and to the car converters when the engine is warm.

There is a tube with a check valve for the heads and another tube with a check valve for the cats. The check valves keep exhaust gasses from backing up into the pump when the pressure of the exhaust is higher than the pressure of the smog pump. That helps save the pump from excessive heat & pressure.

The compressed air directed to the heads combines with the unburned hydrocarbons to burn them more completely.

The air directed to the cats combines with the unburned hydrocarbons and reacts with the catalyst to convert them to water & CO2.

When everything works correctly, the end result is an engine that puts out CO2 and water vapor and very little unburned hydrocarbons in either cold or warm operation.

kdog_x · Aug 4, 2004

Stang8URMPRT said:
You're whole smog system runs off the steel lines that connect to the back of the heads. That is where you get all your exhaust recirculation. Exhaust comes out of there and into the smog pump and to the egr. If you do not have the cross over lines that are on the back of the heads, it's like pulling the heart out of the smog system and it will never work correctly.

Nick

Not correct, first the EGR is on the throttle body (nowhere near those lines), second exhaust does not go into the smog pump, compressed air comes OUT of the smog pump and goes into that first valve. The first valve either dumps it out or lets it pass to the second valve. The second valve (under vacuum) will pass air into those steel lines that go to the back of the heads -- but it only does this on initial startup when the engine is cold. After your car has run for a few minutes the vacuum is removed from the second valve by the computer. The steel lines are no longer used at this point and the air is diverted down to the cats instead of the heads. By plugging the vacuum tube to the second valve air is never diverted to the heads, it always goes to the cats.

As far as the air tube goes, I went and got a stock one but it didnt fit with my longtube headers. So I went back to the boneyard and got one off of a Lincoln Mark VII (they have similar headers). It still didn't reach but I went and bought some heater hose and clamped it down on the exhaust and the air tube. You can also do as jrichker suggested, but that was too much work for me, although it'd probably last longer.

kdog_x · Aug 4, 2004

oops, looks like you beat me to it

5.0guy · Aug 4, 2004

anyone have an answer for my question?

jrichker · Aug 4, 2004

5.0guy said:
I have the pipe that goes to the back of the heads, but that's capped. can I just cap the back of the heads? I don't care about the smog pump, but I don't want to have it venting into the engine compartment because it sounds like one big exhaust leak. I did, however, notice that when I uncapped it, my rpms stuck at about 1200rpm and the revs would take a while to come down. so is this a vacuum leak, too?

As I said, the first diverter valve either passes or dumps air over board. There is a muffler of sorts in the dump side of the circuit. Play with the vacuum on the first valve until you get it to dump through the muffler for the dump side of the system.

You may have some vacuum leaks from previous owners who were not careful about what they cut & capped.

Need explanation of code 44,94

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