I am having a problem with the 4.6L in my '93 Crown Victoria. I am hoping it has enough similarities to the truck engines that someone here can give me advice.

The "check engine" light keeps coming on, and the PCM keeps recording a continuous / engine running fault code 332 (EGR valve opening not detected).

This year of Crown Vic uses a single port differential pressure sensor as the "valve position sensor". When I removed the cover from the top of the pressure sensor, it was full of rust and moisture.

I have replaced the pressure sensor and the vacuum solenoid valve. The tube from the exhaust manifold to the EGR valve is clean, and the metering orifice on the manifold is clear as well. The pressure sense tube to the pressure sensor is clear, too. The EGR valve opens and closes when I draw a vacuum on it, and it doesn't bleed down.

The Haynes manual I have says the PCM uses information from the mass air flow sensor, the throttle position sensor, and the coolant temp. sensor to judge when to signal the vacuum solenoid to port vacuum to the EGR. I am planning to test these items, and check the vacuum lines from the throttle body to the vacuum solenoid.

Has anyone here ever had a problem like this, or can you suggest what I might try next? Someone I work with suggested I jack up the computer and roll a new car under it! I'm not that desperate yet, but I do need to pass emissions testing by next week. Thanks for your help.

Mark L

 

This is a follow up to the message I posted earlier. I have tested the coolant temperature sensor, the throttle position sensor, and the mass air flow sensor. All of them check good per the instructions in the Haynes manual. The vacuum line from the throttle body to the vacuum solenoid is also clear.

What do I do now?

Mark L

 

My EGR problem is now fixed. I searched the posted messages at the F-150 message board, and I found someone with a similar problem.

I removed my throttle body and the 90 degree elbow tube that connects the throttle body to the intake manifold. The tubes that route the exhaust from the EGR to the intake manifold are contained within the casting for the aft-most part of the manifold. The lower mounting surface of the elbow forms the top surface of the tubes. The tubes start at the aft-right side near the EGR valve and run 180 degrees around the back side of the intake throat. There are a total of three ports to the intake throat from the tubes.

The tubes and the three ports were completely packed with exhaust soot and carbon. The EGR system was working correctly after I replaced the bad parts, but since the tubes were plugged, the PCM kept recording a code of 332 (did not detect EGR valve psoition change). There was never a change of pressure within the system because the tubes were blocked, so there was never any exhaust flow being drawn into the vacuum in the intake.

My advice to anyone with EGR problems would be to remove the throttle body and intake elbow and scrape out the exhaust tubes BEFORE you spend any money on new parts. I suspect my position sensor was bad anyway, but I wasted money on a new vacuum solenoid when it was probably OK to begin with.

Mark L