code 94 ?

[backfocus]

I posted part of this about two weeks ago, but now have another? Code 94 keeps coming up, and I thought it was the thermactor (smog) system. Well I have trouble shot the smog system and ended up replacing the hoses as they were getting brittle, but were not leaking. After going through the whole system checking the computer, grounds, soleniods, and valves all are good.

So I was reading another post and saw this.

Code 94 AIR system inoperative - Air Injection
Transmission TCC circuit/solenoid problem - Transmissions

I also saw this on 2 other codes sites.

So is there a solenoid on the transmission. I am not seeing one (I have a T-5)? Or does anyone know anything else about what could be wrong?

 

[jrichker]

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 power for any actuator or relay, 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.

The computer provides the ground to complete the circuit to power the solenoid valve that turns the vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Starting the engine with the computer jumpered to self test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.

If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.
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

 

[backfocus]

Thanks jrichker,

But I have done all that 3 times now as you were helping me before. Everything down to wiring and signals from the computer are fine.

Don't know where to go now?

The car is running horrible loosing power and idles rough only code it shows is 94. Have went through your idle section and cleaned and checked everything twice. Have new EGR, and IAC. Set idle, but still idles at 900 bucking rough. But I can turn the idle screw all the way out and it still idles at 900?????

Here are the problems I know,

1. I do have slightly low vacum about 15 steady (should be between 17-20 I think). I have checked and checked and cannot fine a leak,but replace some older hoses anyway.

2. code 94 test evrything and retested.

3. Cruise stopped working. Haven't had alot of time to trouble shoot this one.

 

[jrichker]

The code 94 won't hurt the idle or cause loss of power. You have a vacuum leak somewhere, possibly under the upper manifold or in the lower manifold to head area. Since the cruse control uses vacuum, I would check the vacuum lines that feed it.

The cruse control shares a fuse with the cigarette lighter. Make sure the cigarette lighter works to test the circuit.

There is a vacuum switch on the brake pedal that bleeds the vacuum off the cruse control when you step on the brake pedal. Make sure it isn't stuck open and bleeding the cruse control vacuum off. This probably won't hurt the idle , but it can keep the cruse control from working