ken3983

I have the solenoid from a 95 Deville 4.9L. I have the shiny metal port of the solenoid going under thw throttle body for the source of the vacuum. Which of the Black ports do I connect on the other side for the EGR valve? One of those black ports has a metal sleeve insert it looks like

bop11

Put a hose on one of the ports and try sucking through it. With no power on the solenoid (disconnected) you should be able to suck through one of the ports. The other port should be closed with no power. The EGR goes to the port you can suck through. This allows the egr valve to close when the ECM closes the solenoid. The other port needs to be closed with no power (solenoid closed) so you don't have a vacuum leak when the solenoid is closed.

ken3983

Thanks for clearing that up, dude. I really appreciate that

ken3983

Okay, I had a short piece of vacuum tube that I plugged up with some RTV and let sit overnight to use as a plug for one of the ports. I used that to put over the port that I could not suck air through. The car ran like crap at idle. So I swapped the EGR vacuum line and the plug that I made around. Same results. I believe the EGR vacuum line goes to the port that I cannot suck air through. So when voltage is applied that port is now open up the vacuum is allowed through. I believe the other port that I cant suck air through with no power is pretty much a vent.

bop11

whooooo. You do not need a plugged hose. The egr solenoid has 2 connections. One goes to the egr valve (the one you can suck through and a second that goes to the intake manifold, (a full vacuum source from the throttle body) usually a line from a point in the valley near the front of the engine underneath the manifold. Visible in the picture just under the stamped upside down 2 on the throttle body in the picture
Typical shown in schematic
If there is a third port, many have a filter over the third port, it is where the air comes into the Solenoid when it is off, hence the filter. When the solenoid is on, this port is blocked internal to the solenoid. When the solenoid is on, the EGR is connected to the vacuum. If there is no filter but a third tube stub, that would have gone to the air intake near the main engine intake filter on the Cadillac. In your case the connection with the metal clip around it should have a peace of filter sponge on it. The clip is to hold the sponge.

ken3983

If you pull up a standard vs25 part, that will be the solenoid I am using. There is a shiny metal port on one side and that goes to the vacuum underneath the throttle body. There are two ports on the opposite side of the solenoid and both are black. With no power, you could suck air through one of the ports. I believe the one you cannot suck air through is the one that EGR vacuum line goes to. I believe once power is going to the solenoid, that Port is now opened up to allow vacuum to pass through. So this solenoid actually has three separate ports total

Bob88GTA

iTrader: (2)

The Foam side port is VENT!

Dyno Don

iTrader: (7)

That is the wrong solenoid for a TPI, that one is for TBI( normally closed)

Both ports should be open, the ECM closes it when the key goes on.
In other words normally open.

ken3983

So what would be a good substitute? Part number?

Dyno Don

iTrader: (7)

I have a used one for TPI with lines $80 shipped

Or the solenoid by its self for $30

ken3983

Do you happen to have the manufacturer part number for that?

Dyno Don

iTrader: (7)

No I don't I think it is the Corvette one.

Bengals89

Question what will happen if there's no sponge. My truck runs fine at idle and when cold but once heated up it bogs down loses power and misfires only in drive and park. In overdrive it's fine or doesn't run as crappy. I've changed everything from plugs wires coil sensors only thing not done is egr and this sponge thing.

ma-harris

I know this is years later since you first posted this, but I really appreciated it. Have an '89 L03 and couldn't find anything that explained where port went to the egr and which went to the tbi. Thanks for that. Even the GM chassis manual has nothing, just a crappy diagram ... like the one on the hood, only worse. :-)