My '87 Ranger with the 2.3l is having trouble with the EGR system and there is a code 34 in the KOER test. My book says that 34 means that RPM did not drop when EGR was engaged. I've definitely isolated the problem to the EGR solenoid, but I want to be sure that it is bad before I spend another $70 on my truck.

There is a small blurb in the manual that states that air should be blown through the solenoid to see if it is bad. There are two vacuum ports on the solenoid, one that runs to the EGR valve and another that comes from the intake manifold. I cannot blow air through the port to the EGR valve, but I can blow air through the port coming from the intake. Is it ok for air to flow through this part of the solenoid, or should it all be sealed when it isn't operating?

 

Does anyone know anything about these old solenoids?

 

Try this link.
http://www.autozone.com/servlet/UiBr...3d800f8d37.jsp
dave

 

Does this mean that air should flow through the vacuum imput side of the solenoid, or something else?

As I said I tried this and air did flow freely through one vacuum port on the solenoid, but not the other. I basically need to know if the one part of the solenoid should be free-flowing, or if both should normally be sealed. It seems like they should both be closed, because wouldn't this constitute a vacuum leak?

 

FWIW, Ford says with regard to a '93 vehicle: DTC 34/334 in Key On Engine Off (KOEO) or Engine Running (KOER) Self-Test indicates that the EGR valve and/or EGR Valve Position (EVP) sensor may not be fully seated in the closed position. The EVP sensor voltage is greater than the closed limit voltage of 0.67 volt. Because of the preload on the installed EVP sensor, it is very difficult to determine whether the EGR valve is seated or the EVP sensor is in contact with the EGR valve stem. Possible causes:

-- Poor continuity in EVP sensor harness.

-- Non-seated EGR valve.

-- Damaged EGR valve.

-- Damaged EVP sensor.

-- Damaged EVR solenoid.

-- Damaged Powertrain Control Module (PCM).

Also, the following are links to an excellent series of short articles that describe all of the Ford EGR systems throughout the years. They offer substantive information on how the various systems work, as well as some good practical testing techniques for each. I'm not familiar with the '87 Ford EGR system but I'm sure you can find a relevant article from the list below:

http://www.tomco-inc.com/Tech_Tips/ttt31.pdf

http://www.tomco-inc.com/Tech_Tips/ttt32.pdf

http://www.tomco-inc.com/Tech_Tips/ttt33.pdf

http://www.tomco-inc.com/Tech_Tips/ttt34.pdf

http://www.tomco-inc.com/Tech_Tips/ttt35.pdf

http://www.tomco-inc.com/Tech_Tips/ttt36.pdf

 

Thanks for all that information. According to that site the vacuum solenoid is supposed to be free flowing normally. I also learned that I might have a problem with my new EGR valve and/or position sensor. They do not hold vacuum for a minute like the article said it should, I have to constantly squeeze my vacuum pump to keep the valve open. Guess I'll need to find the leak there.