I know there is a thread here on finding an alternative egr solenoid for the V6 but I’m surprised there isn’t more talk & effort put in to rebuilding the original one. Even if you have to buy a new, cheap and generic egr valve to pirate parts from.
I have seen a thread or two over the years of some who have dissected one and posted pics. Again, I’m surprised more people (who need one) are not going down this path.

Your input??
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 08-17-2022).]

I recently took mine apart to figure it out and was surprised at how simple it is (and saw the other threads about it here). It's just an electromagnet that attracts a metal disk - rewiring one isn't hard. I've had three examples now where the metal winding is shorted, but the vacuum switch is fine. Seems if you just connect up any old solenoid that controls the flow of vacuum it should work. I searched for the cheapest EGR out there, and found one for $9 on a Mazda, part #911-707. Will caveat that I don't know if it works, as my check engine didn't seem to activate with the original unplugged. Of course its not real pretty, but a motivated person could package it up okay I think.

Rewinding...

I did a test on my 85 GT today. I put a vacuum gauge in-line with the hose that goes to the egr valve, warmed up the engine, revved it to 2500-3000 rpm and the vacuum gauge barely read 2.5 hg. I heard the minimum is at least 5 hg. Despite no codes, I think my egr solenoid is not allowing vacuum to get to the egr valve. And my Nox is way too high.
Kit

quote Originally posted by Kitskaboodle: I did a test on my 85 GT today. I put a vacuum gauge in-line with the hose that goes to the egr valve, warmed up the engine, revved it to 2500-3000 rpm and the vacuum gauge barely read 2.5 hg. I heard the minimum is at least 5 hg. Despite no codes, I think my egr solenoid is not allowing vacuum to get to the egr valve. And my Nox is way too high. Kit

Check your EGR valve and the connections on the vacuum lines. To check the EGR valve, disconnect the vacuum line from the valve. Feel under the valve and push up on the plate / diaphragm. While holding the diaphragm up, place your finger over the port on the EGR valve. Release the diaphragm. You should feel the vacuum suck your finger against the port and the diaphragm should stay in the up position. It it doesn't or the diaphragm slowly returns, you probably need a new EGR valve - which are still available from Summit, Rock Auto, etc.

You should also check you vacuum lines and the rubber connectors. Sometimes the plastic lines age and split. I found that my problem was a bad connector at the EGR solenoid valve. I replaced it and resolved the problem.

It the problem is a split or broken vacuum line Rodney Dickman and the Fiero Store sells replacement sets.

Hi Mike, those are all good points & suggestions. Before I took my egr solenoid off this afternoon, I checked all the connections and everything looks good. However, I probably need to verify the full integrity of the hard lines that go under the plenum. As an fyi I just changed the cat, new 02 sensor, new egr valve, Seafoamed engine and Seafoam in the the gas tank and it failed with high Nox. Going on the basis that my egr solenoid is BAD, I decided to take off my egr solenoid, take it apart and try to see what is the issue. I heard the coil winding wires often break/ have contact issues. Mine look “so-so” with only a small amount of corrosion. I’m going to resolder the leads onto the connectors, clean everything up and then apply 12 volts and see if she “clicks”. My gut feeling is one of the components in the potted square box is bad.
In that case it will be time to look for another unit. Taking one apart has been a great learning experience! Here is a few pics of the disassembly:
Kit[img]https://images.fiero.nl/userimages/Kitskaboodle/ 35F79F7D-0E46-49DF-B417-C3FCE130B817.jpeg[/img][img]http s://images.fiero.nl/userimages/Kitskaboodle/985616A9-52D1-4B54-904E-3FCAEF81A37B.jpeg[/img]

[This message has been edited by Kitskaboodle (edited 08-18-2022).]

Not a permanent fix but if you need it to pass smog you could borrow the one I have from the motor I pulled. If you want to swing by and see if mine makes any difference on your motor, send me a pm.

shem

Thanks for the offer Shemdogg! 😀
My 86 GT has a good one if I need to do that. I’m hoping that my “refurb” fixes my problem. If not, I’m hoping to get one soon from a local yard.
Kit

There are some stone like filters in the inlet of the solenoid that seem to get clogged. The last one i messed with had perfect vacuum but it was not making it to the egr. After i punched out the filter stones everything worked properly

Stone like filters?
Is that located in the long round filter portion?
Kit

They were on the lid with the vacuum ports. I discovered them by accident when i was getting poor flow through the disassembled solenoid ports and poked a tool in there to try to clear the ports. They obviously are to prevent things getting sucked into the solenoid but idk how you would clean them.

Ok, you are referring to the twin port tubes. Mine are clear.
Thanks for reminder to make sure they are clear.
Kit

Ok, I cleaned up the solenoid, re-soldered the leads from the coil winding to the connector ends and then put it all back together.
Then, I ran 12 volts to the solenoid (per a video I saw on YouTube (Matt) but mine seems to be dead. (No clicking)
Looks like mine is toast.
Kit

Honest that thing is a PITA to bench test. It doesn't click. You have to run a vacuum on it and then trigger it.

Ok, I tested it again with my MightyMite vacuum tester and it’s still showing 2.5 hg or less at full operating temperature at 2500 or so rpm.
According to the booklet that came with the test gauge, there should be a minimum of 5 hg or greater when fully warm.
Is anyone able to do a vacuum test on their V6 Fiero to see what vacuum reading you get while teed in to the egr valve vacuum line?
I would like to see what vacuum reading you are getting.
As an fyi I swapped out the egr solenoid from my other Fiero and it’s still giving the 2.5 hg vacuum reading as my old one and this Fiero passed smog a few months ago so I know that egr solenoid is good.
I’m getting confused. Kit
P.S. I verified that there IS 12 volts getting to the egr solenoid. Also, the hard plastic vacuum lines look to be ok although it’s hard to verify it because most of it is under the plenum.

[This message has been edited by Kitskaboodle (edited 08-22-2022).]

quote Originally posted by Kitskaboodle: .... Also, the hard plastic vacuum lines look to be ok although it’s hard to verify it because most of it is under the plenum.

Try isolating the vacuum lines under the plenum by locating both end of each line. Block off one end with a cap of the appropriate size and use the Mity-Vac to see if it will hold a vacuum. You should be able to tell if the lines are good using this method.

Good idea. Thanks fir that suggestion,
I was also thinking of doing the exact opposite. (for a different reason) I thought about blowing air through one end to see if one of the lines is blocked.

Also, I’m very interested to see what your vacuum gauge says when at full operating temp.

By the way, I contacted the FieroStore yesterday and asked them to consider offering the Fiero V6 egr solenoid. For different reasons the answer was no.
Kit

quote Originally posted by Kitskaboodle: Ok, I tested it again with my MightyMite vacuum tester and it’s still showing 2.5 hg or less at full operating temperature at 2500 or so rpm. According to the booklet that came with the test gauge, there should be a minimum of 5 hg or greater when fully warm. Is anyone able to do a vacuum test on their V6 Fiero to see what vacuum reading you get while teed in to the egr valve vacuum line? I would like to see what vacuum reading you are getting. As an fyi I swapped out the egr solenoid from my other Fiero and it’s still giving the 2.5 hg vacuum reading as my old one and this Fiero passed smog a few months ago so I know that egr solenoid is good. I’m getting confused. Kit P.S. I verified that there IS 12 volts getting to the egr solenoid. Also, the hard plastic vacuum lines look to be ok although it’s hard to verify it because most of it is under the plenum.

This sounds like you have a vacuum leak. I just went through this with CA smog in June. Test the vac from the intake to the solenoid then test it after then test it at the egr. Somewhere in there you will find low vac. What i typically do is pull the intake line put my thumb over it and run some vacuum from the solenoid side (just the vacuum tube) then i do that same thing the egr side.

quote Originally posted by Kitskaboodle: Ok, I tested it again with my MightyMite vacuum tester and it’s still showing 2.5 hg or less at full operating temperature at 2500 or so rpm. According to the booklet that came with the test gauge, there should be a minimum of 5 hg or greater when fully warm. Is anyone able to do a vacuum test on their V6 Fiero to see what vacuum reading you get while teed in to the egr valve vacuum line? I would like to see what vacuum reading you are getting. As an fyi I swapped out the egr solenoid from my other Fiero and it’s still giving the 2.5 hg vacuum reading as my old one and this Fiero passed smog a few months ago so I know that egr solenoid is good. I’m getting confused. Kit P.S. I verified that there IS 12 volts getting to the egr solenoid. Also, the hard plastic vacuum lines look to be ok although it’s hard to verify it because most of it is under the plenum.

2500rpm in gear or just at idle?
Do you know if the 12V you see is actually meant to *activate* the solenoid, or is it just a power supply and not a switch? I don't know it's wiring scheme.

I might have misunderstood your test, but if you're relying on the car to activate the solenoid then it has to be in gear driving down the road. The ECM doesn't activate the EGR solenoid at idle.
It also has to warm up to some minimum coolant temperature and meet some other criteria (programmed in the chip). A leisurely cruise will allow EGR, heavy load or idling will not.
I used to get the warning light within a few minutes of driving so the temp threshold isn't very high.

Also, have you checked that the EGR valve holds vacuum if you lift the valve and then cover the port? New parts aren't always good.

My understanding is. The EGR should open when you go from idle to 2500 in park or neutral. When you are under loads at freeway speeds, The solenoid should trip and waste the vacuum causing the egr to close.

[This message has been edited by skywurz (edited 08-26-2022).]

Just as an fyi my Nox was very high while at the smog check station while on the rollers at 15 and at 25 mph. The smog test on the rollers at these two speeds is a requirement for my car here in Calif. if the egr is NOT opening during these tests, then my car will never pass. This is the root of my problem: EGR closed equates to very high Nox. In summary, my egr is not opening. Either non it’s own or it is not getting the vacuum to open.
Kit

Do you still only see 2.5 hg of vacuum? You are going to need to see 8 hg or so. I want to say I was able to get 12 or so from the intake at 2500 rpm and then 8 on the egr tube.

Yes, still 2.5 hg.
I’m going to check my vacuum lines this morning to make sure they are ok. (the two that go to the egr solenoid)
Will report back later this morning.
And thanks for not giving up on my problem. 😀

It still sounds like a vacuum leak somewhere. Did you check all the vacuum lines? (brakes booster, cruise, etc.)

Try this thread. You're started it in 2014. (https://www.fiero.nl/forum/Forum1/HTML/093972.html)

If that doesn't help have a look at this one. (https://www.fiero.nl/forum/Forum2/HTML/145280.html) It shows the valve arrangement in the EGR solenoid valve. Maybe there is a blockage there?

As an fyi I took off the egr solenoid from my 86 GT (which passed smog about 3-4 months ago) and put it on my 85 GT but I’m getting the same result. (almost no vacuum getting to the egr) I’m beginning to think that both of my egr solenoids are ok and that somehow the egr solenoid is not being told to open.

I did not verify booster vacuum hose
or cruise hoses but I will do that.
Other than that, I’m stumped here.
Why am I not getting vacuum to the egr valve?
Kit

Can you hook up WinALDL or some other datalogging tool? One of the parameters will tell you if the EGR is being commanded to open. Then you'll know it's a failure downstream.

I still don't think the ECM commands it to open without being in gear, even at 2500rpm. I could be wrong though, best way to be sure what ECM is trying to do is to datalog it.
Other option is to figure out the signaling scheme and probe the signal wire, assuming it's a simple voltage level.

The "two speed idle" test doesn't check N2O, even at 2500rpm, because they don't expect EGR to necessarily work in that condition. I wouldn't assume it does on the Fiero until you can see it's being commanded.

I tried looking in my old datalogs, but didn't find anything to confirm because I don't have much logs with the stock chip, and what I do have doesn't show me revving high enough to prove anything.

[This message has been edited by armos (edited 08-28-2022).]

quote Originally posted by armos: I tried looking in my old datalogs, but didn't find anything to confirm because I don't have much logs with the stock chip, and what I do have doesn't show me revving high enough to prove anything.

Is this info from a 2011 datalog of any help? I believe it was taken from my '86 GT, and it should be with a stock PROM, although I can't swear to it.

quote Originally posted by Kitskaboodle: As an fyi I took off the egr solenoid from my 86 GT (which passed smog about 3-4 months ago) and put it on my 85 GT but I’m getting the same result. (almost no vacuum getting to the egr) I’m beginning to think that both of my egr solenoids are ok and that somehow the egr solenoid is not being told to open. I did not verify booster vacuum hose or cruise hoses but I will do that. Other than that, I’m stumped here. Why am I not getting vacuum to the egr valve? Kit

You need to check the other vacuum line going to the solenoid. The one coming from the intake. You should get 8-12 hg at 2500 rpm. If not the hardline is probably broken between the intake and solenoid.

Ok, I will check the other line tomorrow and report back. Thanks for no giving up on me. 😀
I really want to solve this problem!
Kit

quote Originally posted by Kitskaboodle: Ok, I will check the other line tomorrow and report back. Thanks for no giving up on me. 😀 I really want to solve this problem! Kit

I eagerly await your results. My GT also failed for high NOx, with a new cat, new O2 sensor, and new rings.

Ok, I did two more new tests today.
Test #1 / I disconnected the hard line/elbow under the throttle body, (that goes to the egr solenoid) I then plugged/capped it and then I checked for vacuum at the other end that goes to the egr solenoid. (it held vacuum solidly)

Test #2 / I then plugged the hard line/elbow back in, (that plugs in under the throttle body) then I connected my vacuum gauge to the other end of this same line (that goes to the other nipple on the egr solenoid) then I started the car, warmed it up, then I applied around 2200-2400 rpm revs and the vacuum gauge read around 10 hg.

And just for the heck of it, I tested the vacuum again (coming to the egr valve / with the engine running) and it still barely registers 2 hg at 2300-2400 rpm. (as a reminder, as I previously mentioned, the hard line going from the egr solenoid to the egr valve holds vacuum without issue)

Lastly, since someone mentioned this above, I did check the hose going to the booster and also the hoses going to the cruise control and both look ok.
Kit

[This message has been edited by Kitskaboodle (edited 08-29-2022).]

Alright so when you had your egr solenoid apart you could see through the nozzles on the cap?

Yes!
I did check that as I had heard one person say theirs was clogged with “stones”.
Also, don’t forget that I swapped out the egr solenoid from my 86 GT (which passed smog a few months ago) and I’m still having the same problem.
Kit

go back to basics? this is the end all bible of the EGR IMHO https://www.fiero.nl/forum/Forum2/HTML/045528.html

shown in the diagram you can see the brass filter. In my case mine was clogged.
Have you tested for OL or shorts on the solenoids?
is it possible both solenoids are bad but you happen to have the fresh air inlet capped somewhere on your GT? This would force the EGR to function all the time.

When I took the egr solenoid apart I don’t remember seeing a brass filter.
I though I had verified that the twin port cap thingy was clear. Maybe I need to recheck it.
Check OL? What is that? No, I did not verify the copper winding continuity. I did resolder the ends of the copper wires where they attach to the connectors.
Getting more confused by the minute.,..,
Kit

[This message has been edited by Kitskaboodle (edited 08-30-2022).]

You should read through the full post I shared. OL is open loop meaning no connection on the coil.

Ok, per BuddyCraigs thread, I did 3 more tests this evening:

All tests below were done with my ORIGINAL egr solenoid (that I had on my 85 GT) on my workbench and fully put back together. (that I failed smog with) To remind you, I took it all apart to clean, inspect, repair and then put it all back together. Since after I put it back on the car and was still not getting vacuum to the egr valve, I decided to put on the egr solenoid from my 86 GT since I know it is good.
Anyways, that one is still on my 85 GT.
These tests are to show if my original one is ok or not ok. (As I mentioned previously, I took it all apart but it looked mostly ok)

Ok, here we go.
Test #1 / Tested continuity at vacuum sensor (top two pins) and it registered a flat 0.0 ohms (i.e. OPEN)

Test # 2 / disconnected short vacuum hose that goes from egr solenoid nipple to vacuum sensor, then hooked up vacuum pump to hose that goes to the vacuum sensor, then while reading the ohmmeter readings from the top two pins, I applied about 5 hg of vacuum. The ohm reading went from 0.0 to about 0.6. When I disconnected vacuum gauge, it went back to 0.0 (of course)

Test # 3 / I probed the bottom two pins on the egr solenoid and it measured 95.0 ohms.

These figures seem to be inline with BuddyCraigs findings. I think my ohmmeter is a little better (and probably more accurate) I have an Innova model 3320.
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 08-31-2022).]