EGR Solenoid Questions (Page 1/1)
Romsk SEP 02, 12:09 PM
Hello all,

Today I pulled off the EGR Solenoid from a 87 Fiero GT V6 2.8L engine.
I found that the hose on the side of the unit (the side that appears to be a filter of some sort) was broken. I bought 5 feet of new hose but I have no idea from where it connects.
I could not find the other end.

Can anyone tell me where that hose goes?

See photo below.

Also:
There is an open metal tube against the fire wall.

Is that supposed to be open?
What is it for?

Between 2 contacts on the EGR Solenoid I read 7 Mega Ohms in one direction and infinite Ohms in the other direction (meter leads swapped).

Is this correct?

The Vaccum Switch seems to be working properly. At least when I disconnect it from the T and apply vacuum to the elbow on the switch.

I am not sure if the valve is supposed to leak when powered off, I can blow light pressure through all 3 ports and hear air escaping.
But my main concern at the moment is to what that "fat" vacuum line is connected.

Why are there 3 vacuum hoses? I would expect only two.
Is this a true simple solenoid (off or fully actuated) or is it more complex?
I was expecting a simple solenoid coil that would read about 50 Ohms or so, but that assembly under the Vacuum Switch has all four wires going to it - is there some sort of electronic circuit beyond a simple solenoid coil?

I saw some drawings of an EGR Solenoid, but I cound not figure out what was going on with the valve ports inside.
Thanks.


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Paul Romsky

[This message has been edited by Romsk (edited 09-02-2022).]

fierofool SEP 02, 12:28 PM
The hose in question connects to a metal tube on the front firewall. There are 2 metal tubes there. The larger one isn't used now, due to a recall and it was replaced with the metal tube that inserts into the front valve cover and into the air intake tube just in front of the throttle body.. The smaller metal tube attached to it is where the solenoid attaches. Peer in between the valve cover and the passenger side decklid hinge and you should be able to see and reach it.
Romsk SEP 02, 12:39 PM
fierofool,
Thanks, I will look for it now.

[This message has been edited by Romsk (edited 09-02-2022).]

Romsk SEP 02, 05:06 PM
fierofool,

I found it. It was behind/under a big fat wiring harness. I had to break out my inspection camera to find it. It was right were you said it was. Knowing where to look was a great help.
Thanks.

I am not going to hook up the hose until I replace the Coolant Temp Sensor (CTS) - you told me how to get to it in another thread (hence my removing the EGR Solenoid today). My CTS is reading Voltage Low (0x00) from the ECM and the associated MALFLAG1 bit is set. My SES is something I have yet to fix.

I pulled off the two pin connector on the EGR Solenoid to the ECM and hooked up a potentiometer to it... I got different values as seen in the ALDL stream, so the wiring is good and the CTS is bad (open). I have one on order.

So, with this EGR Solenoid hose broken off (wide open), I guess I was getting a vaccum leak and most likely a major cause to my engine running like garbage - do you agree?
I will not start the engine until I have it all back together.

To what does that other end of the steel tube connect?
What does this line do for the EGR Solenoid? Why is there a filter on it?

Thanks again,
Paul
fierofool SEP 02, 05:37 PM
That hose being off the solenoid won't cause a vacuum leak. It's open on the other end when connected to the metal tube. The metal tube transitions back to a small rubber hose that attaches to the air filter canister.
Romsk SEP 02, 08:49 PM
I see, so it goes back to the air cleaner - after the air filter I assume.

I found this:
In order for the EGR solenoid to accurately deliver the engine vacuum and to release any trapped vacuum when closed, it needs a vent to the atmosphere. Releasing vacuum really means allowing air to enter, so a filter is used to keep dust and dirt from being ingested by the solenoid.

Ok, it's a release vent (brings air in to cancel the vacuum out - so vacuum is not trapped inside the tube/line/hose and the EGR!
And it takes atmospheric air that is away from the hot engine area, hence it goes over towards the air cleaner to vent in where the air is cooler.

Ok, so this hose being disconnected from the air cleaner is not the cause of my engine running poorly.

I am hoping that replacing the faulty CTS will get it to run better. I have read that a bad CTS can play havoc with the ECM and how the engine runs.
If that doesn't fix it, I will check/clean/replace the IAC valve.
After that it may be fuel injectors/system or the ECM.

[This message has been edited by Romsk (edited 09-02-2022).]

theogre SEP 02, 09:44 PM
EGR valve is on the VECI label on(under) the deck lid. Example:

one vac line goes to a port on the TB.
one vac line goes to EGR itself.

3nd valve "port" goes No Where. All that does it dump vacuum on EGR port when valve is off.
Many of these (not just the one use w/ that V6 version.) have/had a small filter so dirt etc won't get into the thing.
To fix a bad/missing filter... try cheap "air stones" from anyplace sells aquarium stuff. Often can pry off or cut them to push on the vent port direct. If not try short hose to connect them.

V6 "Fire" Recall reworks the PCV plumbing and old hard line on firewall just left alone. That has Nothing to do w/ EGR.
For V6 input side PCV was after Air Cleaning so gets clean air. Has nothing to do w/ vacuum there. PCV itself gets way more vacuum to it's job and weak vacuum anywhere won't matter.

Fiero 4cyl and a lot more PCV input have separate air filter because while in same house, it gets air before main filter.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Romsk SEP 03, 06:31 AM
fierofool and theogre,

Thanks for the info, I now understand how every sensor works and I have a way to bench test them all.