EGR troubleshooting on 1988 5.0
 

I get a code 33 (EGR valve not opening) on my 88 stang. There is no vacuum at the EGR. Does anyone know how to test an EGR vacuum solenoid?

code 33 (rc*): Insufficient EGR flow detected


You can do a quick check of the EGR valve and solenoid by connecting a test light to Battery - and back probing the connector with the engine running. On one side the lamp should be bright. This is 12v (VBAT). Back probe the other (ground) side of the connector. This will slightly energize the solenoid and partially open the valve. This will tell you that the solenoid and valve are able to operate.

Thanks for the reply! I'll let you know how it works out.

The valves themselves often carbon up and have a hard time opening, taking it off and cleaning it with some carb cleaner can remedy the situation.

Be sure to clear your codes after doing this to make sure its working correctly.

I don't suspect the EGR valve anymore. I bypassed the EGR solinoid by removing the vacuum supply line from the solinoid and connecting it directly to the EGR. I can watch the EGR rod move back and forth when I apply and then remove vaccum. Using an analog voltmeter I watched the votage on the ground side of the EGR solinoid fluctuate from 12V to less than 12V (momentarily) when the engine is warm and I open the throttle. I believe this tells me that the computer is telling the solinoid to open. I then removed the solinoid from the car and, at my work bench, applied 12V to the coil with a vacuum at the bottom vaccum connection. The solinoid did not open and allow vacuum at the top vaccum connection.

In my oppinion the solinoid is bad. A new solinoid is $58 plus tax at Al Pal ford. Do you think my troubleshooting makes sense? Should I buy a new solinoid from the dealer or try a different source?