Pulled codes, quick ?

sgarlic said:

I just pulled codes from my 88 GT.. with car running I got a 21, 94, 44, and 33. What I'm seeing is that most of them are relating to air system .. which air system are we talking about ... the air pump? It also looks like one has to do with the EGR valve.. the car was just a little below operating temp so would the egr valve not be open at this point? I'm not too worried as it looks like most of these are nothing big. Thanks for any help.

Click to expand...

they mean the "air pump" emissions system. i don't think it's any thing to worry about

FWIW it can make the car run lean & be down on power & get sucky gas mileage... emmissions aside.

21 is coolant tempature sensor out of specified range.

33 is canister or Valve not operating correctly

44 and 94 have to do with your smog system is it removed? If so pay them no attention

21 could be the cause of your cold idle issues you were describing in the other thread, although I believe the computer will sometimes throw this code if you don't have the engine up to operating temp. when you do the koer test. For 33 I would try taking the EGR valve off and cleaning it first.

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Code 33 - Insufficient EGR flow detected.
Look for vacuum leaks, cracked vacuum lines. Check to see if you have 5” of vacuum at the EGR vacuum connection at cruse RPM. Look for electrical signal at the vacuum regulator solenoid valve located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, 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