EGR Valve????

gooch06 said:

In my 1990 Lx 5.0 I'm getting a code 33. I tried replacing the EGR Solenoid and the EGR Sensor but still have the code. Do you think it is worth it to change the EGR Valve? Will the car suffer any way if I just leave it alone? Will it pass emissions or will gas mileage suffer??? Please advice on this Valve. Thanks

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If there really is a problem with the EGR system fuel economy could suffer.

Did you disconnect the battery to clear the codes?

Emissions will most likely be trouble some (again assuming there is a real problem with the EGR), but that depends on whether or not you will be tested for NOx. Some areas only test HC and CO.

You could try to clean the valve as a quick fix. It has been known to stick due to carbon buildup.

Code 33 - Insufficient EGR flow detected.
Look for vacuum leaks, cracked vacuum lines, failed EGR vacuum regulator. Check to see if you have 10” of vacuum at the EGR vacuum connection coming from the intake manifold. Look for electrical signal at the vacuum regulator solenoid valves 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.
Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1 ohm.

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

EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 5in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM.
should read about 5in vacuum

Its always better to find the cause of the problem as opposed to just throwing parts at it until it goes away. When you replaced the parts you have already you have to reset the KAM or the codes will still be there.