1989 F-250 2WD with 7.5 liter (460) fuel injected and C-6 Auto.

Scanner shows code 33. Books says this is:
EGR Valve Position (EVP) sensor or Pressure Feedback EGR (PFE)sensor indicates EGR valve is not opening

or

EGR Valve Position (EVP) sensor or Pressure Feedback EGR (PFE)sensor indicates EGR valve not seated (closed) properly.


I think I know what (and where) the EGR valve is. I understand it's operation, so now what?

Is it common to replace the entire EGR valve?

Any ideas?

 

There are as you have indicated two different sensors for the EGR. The PFE sensor measures pressure as the EGR valve opens and closes. The position sensor monitors the actual movement of the EGR valve. In the case of the PFE make sure that the hose connection on the sensor isn't melted shut, since some of these are plastic and this is known to happen. Check the hose for any cracks and a tight fit. If the connection is melted you can try to open the fitting by carefully drilling into the end where the hole ahould be. If it works you save yourself about $75. In any case you need to test the EGR to make sure it is working properly. While at idle apply vacuum to the EGR valve and see if it causes the engine to run rough and/or stall. If it doesn't then the diaphragm is shot and you will need a new EGR. If it does then you probably have either a bad sensor or bad EGR valve control switch. You can find the control valve by following the vacuum hose from the EGR back to it. Probably not your problem, it is more likely to be the sensor or the EGR valve.

Before you assume any parts are bad make sure that you check your vacuum lines and connections. Cracked hoses have caused many a bad diagnosis as to a problem. Also, check your engine vacuum to find any vacuum leaks. You should measure at least 20 mg at idle in neutral. I am assuming that you have a vacuum gauge to test with.

One last thing, I had this same code come up when I had a plugged catalytic converter. The way to find out if you have a plugged converter, attach a vacuum gauge, get the engine fully warmed up, gradually bring the engine to about 2000 rpm, hold it and watch the vacuum gauge. It should rise and stay, if it drops radically then you probably have a plugged converter or some other exhaust blockage.

I realize that this seems to be a lot of checking, but if you don't check a number of possibilities out, you run the risk of not solving the problem and spending a lot of money on parts that you didn't need.

John

 

I had the same code come up. The engine computer signaled the "Check Engine" light to come on. I downloaded the code and troubleshot the problem. The first thing I did was to install a vacuum hose/tube to the top of the EGR valve and applied a little human vacuum to it (no tester available at the time!). The valve never opened; didn't apply too much vacuum because I didn't want to rupture the diaphram. Did it a second time, but this time I tapped on the cast iron portion of the valve while sucking on the hose and the it popped open. Replaced the valve and it solved the problem.

If you plan on doing this procedure and are not familiar with the vale or its location, you may want to find someone who could assist you.