[Beav]

You don't. If you lube it one a several things will happen:

1 - The lube will evaporate and may leave behind a residue that...

2 - Might 'coke' from the extreme heat present and make the valve sure to stick.

3 - Your lube of choice may also rot the valve's diaphragm. This is not a good thing because...

4 - There may not be anything wrong with the actual EGR valve itself and 'lubing' it may in turn cause it to go bad.

Once again, let's think of how the ECU will determine the EGR valve is 'bad'. There are a number of ways to accomplish this but the SVX uses (as most Japanese engines do) a heat sensor. When the ECU commands the EGR valve solenoid to open, it allows engine vacuum to flow to the EGR valve (we won't concern ourselves with the transducer here), causing the diaphragm to lift the pintle from its seat and allow exhaust gasses to flow into the EGR port to the intake manifold. The ECU knows what temperature the port was before it commanded the solenoid to open so it looks for an increase of xx degrees to occur within x amount of time. Pretty simple. However, as many of you have read before, that doesn't mean that the EGR valve itself is actually bad! What if a vacuum hose fell off? The solenoid was bad? The temp sensor went south? A wire got pinched in half? How about if the port(s) was clogged, that wouldn't allow flow even though everything else was o.k.?

Sorry, no magic here either. It'll take a few extra minutes to figure out and save yourself money. With a bi-directional scanner (one that allows you to command certain things to occur. normally only available to OE scanners and only on OBDII cars) one could command the EGR valve to open and watch the temp rise as reported by the EGR temp sensor. OBDI? hahahaha... no way unless you know when the solenoid is commanded open. How to diagnose? Remove the connector from the EGR solenoid and attach a switched 12v power lead to one pin and ground to the other. With the engine running switch the power on. If the engine dies the EGR solenoid and the valve are working and the ports are flowing. In that case check the EGR temp sensor and wiring. If the engine doesn't die remove the vacuum tube from the solenoid and check for vacuum with engine running. If vacuum is present reattach tube, power up the solenoid and check for vacuum at the EGR valve. If that is o.k. you'll probably have to remove the EGR valve to see if it works when vacuum is applied, I think the SVX EGR valve is pretty closed-up to visually watch it operate while installed. Before you do that you may want to check the ports, typically on EFI cars the EGR ports will clog inside the manifold or throttle body, wherever they happen to be on a specific engine. I think Matt indicated the SVX location before.