Kit,

You have enough observations and test results now that it's getting hard for me to keep it all straight. It's not clear to me if you have shown that the:

1 - solenoid works on its own, by applying power directly to the terminals, and
2 - the wires/connector for the solenoid are delivering the proper signal at the proper time.

Yes? Since both solenoids produce the same result (2.5 Hg) and your lines hold a vacuum, this suggests that the signal going to the solenoid isn't working correctly.

quote Originally posted by Patrick: 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.

Based on earlier posts it sounds like kitskaboodle is trying to test EGR by revving at 2500rpm while stopped. This looks like a driving log where you stopped at some lights, but I don't see any revving except while actually driving.


I was curious so I found my stock chip and tried it. It does work, at least on my car. In fact, looks like EGR will start to open somewhere just below 2000rpm, and is definitely open at 2500rpm in Park. Once open, it wanted to stay open until RPM got much lower.

This is with the 'AATC' chip - 1986 V6 automatic 3.33 California.
The Y-axis is showing RPM, the numbers would be different for the EGRDC sensor but you can see EGRDC coming up when it revs high enough. The "Speed" and "Park/Neutral" graphs don't show well but I promise it was sitting in Park the whole time.
Caveat: my EGR solenoid doesn't actually work, but no code 32 was detected yet so I don't think this influenced the ECM at all.


@Kitska - 1985 uses a different ECM and I don't know if yours is auto or stick, so it's always possible your EGR is programmed to behave differently, but good chance it's the same.
So I agree now, it probably *should* be activating EGR when you rev at 2500rpm.
If you can, it would help narrow down the problem if you can test whether it actually is commanding EGR. WinALDL can do that (look at the EGRDC value), or there's probably a signal wire that can be probed with a multimeter (I haven't looked into the wiring scheme). Even better if you can check both - if WinALDL and the signal wire don't agree then that presents some different possibilities.

If you can confirm that the solenoid is being signaled to open EGR, but at the same time that there is no vacuum during that command, then you'll have a better pinpoint on the issue.

quote Kitskaboodle Test #1 / Tested continuity at vacuum sensor (top two pins) and it registered a flat 0.0 ohms (i.e. OPEN)

I don't know if this is a simple mistype or if it changes the test interpretation - but just in case I should point out that 0.0ohms is a dead SHORT - not open. An open would show as "OL" which is near infinite ohms.

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

Here is pic of the test you are questioning.
Meter is reading 0.L If you are correct than mine is reading infinite ohms. (for this test)
So far, it looks like it is doing what it should according to the buddycraig thread. However, I’m a little confused about the last step where he applies 12 volts to the solenoid pins while putting his finger on the brass block off plate. Also, maybe me is all put back together as you can see in my pic.
Kit

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

quote Originally posted by armos: This looks like a driving log where you stopped at some lights, but I don't see any revving except while actually driving.

It's been a long time since I was an adolescent.

I forgot to answer your question.
My 85 GT is an auto.
Kit

Update:
Because I’m at a loss as to why my egr is not being “commanded” to open, I decided to take a gamble and bought another ECM from an 85 SE. I was hoping it was a computer issue. So, I swapped ECM’s this morning and then checked vacuum at the egr valve after being fully warm. Unfortunately there is no change. ( h.g. Is still only 2.5 at about 2K rpm but book says it should be 5.0hg minimum.
I’m about ready to give up.
I’m totally at a loss as to what is wrong.
Kit

It was mentioned above that it is possible that the ECM only triggers the egr solenoid to open while in Drive. I’m thinking this is not correct but since I’m at a standstill anyways and making no progress, I decided to do a little experiment. I don’t have a scan tool / Winadl, etc so I’m going to tee in to the vacuum line going to the egr valve, run the vacuum line outside onto the decklid / rear window area, hook it up to my mighty Mite vacuum gauge, tape it down to the decklid, then drive down the road at speed, warm it up abs see what the vacuum is then. (at 2500 rpm in Park it would only register 2.5 hg)
My bet is there will be no difference.
Stay tuned…….,,,
Kit

As promised, I ran a real road test this afternoon and as suspected, there is still no difference in egr vacuum whether sitting in Park or driving down the road. (2.5 hg at the egr valve)

I did a few more tests as well to double check my previous findings. I tried both egr solenoids from both my Fiero’s and had no change in egr vacuum. I checked both plastic hard lines that go from the egr solenoid to the egr valve and the other line that goes to the underside of the throttle body. (I plugged one end and applied vacuum at the other end to see if they would hold a steady vacuum. (they did)

Question:
What would happen if I re-routed the egr valve line directly to the throttle body or intake? This would make the egr stay open all the time.
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

Kit, would you mind posting your numbers from the smog test? I found a vac leak on my GT, fixed it, and re-set the timing, and failed again for high NOx. All other numbers look good and the car runs great except a little popity-pop from the exhaust during shifts. I'm going to buy a mityvac and run your tests and start a post dedicated to that.

Ok, here is the “report card” for my 85 GT.
As an fyi, I forgot to mention that I replaced the ECM (with one from another 85 Fiero V6) but it did not help.
Also, I made sure both of my egr solenoid brass filters were clear. (they were)

On another note, I really need a few V6 folks to test their egr vacuum hg at full operating temperature.
Kit

[This message has been edited by Kitskaboodle (edited 09-20-2022).]

Electrical side:
You should be able to activate the solenoid by applying 12v to the 2 pins, so no need to rev the engine (get a spare connector from the junk yard to make it easy). This will eliminate any issues with the wiring in the car. If the system now "works", then you know there is a problem with the wiring. IIRC you said you have 12v on the connector, so there could be a problem with the wire going to the ECM.

Vacuum side:
What is your vacuum reading at the input to the solenoid?
You have stated you only get 2.5 hg at EGR, but what do you get at the output of the solenoid (when it is suppose to be open)?


This is my thinking with regards to vacuum test (power applied so valve is open):

If bad at input = something wrong with this line (blocked, leak).

If good at input and bad at output = something wrong with solenoid as it is not opening. This could be electrical or mechanical. Maybe coil is weak, piston not moving, etc.

If good at input, good at output, bad at EGR = something wrong with line going to EGR (blocked, leaking?)


edit:
As an added thought, if you are not getting in codes, this makes me think that you are getting proper vacuum at the output of the solenoid as this is where the sensor is that would cause a code to be thrown (unless the 1 port of the "T" that goes to the EGR is blocked).

[This message has been edited by Mickey_Moose (edited 09-22-2022).]

I have never had a check engine light.
Thanks for all the advice / questions!
I will get back with you on them
Kit

Ok, here is what I did this afternoon:

I found a way to verify that the egr solenoid is getting 12 volts to the lower two pins (that command’s the egr solenoid to open) at the proper time. I unplugged the 4 pin connector, put my ohmmeter test leads on the bottom two pin connectors, then read the meter for voltage as i increased rpm’s. At idle the voltage was all over the place on the meter but as I revved the engine over maybe 1800 rpm or higher, the meter would then begin to show 12+ volts. This confirms that the ECM is triggering the egr solenoid properly to open.

For the next test, I then plugged the 4 pin connector back on the egr solenoid, then I took off just the hose/line that goes out from the solenoid “T” junction nipple, (and goes to the egr valve) hooked up a separate vacuum hose to this nipple and ran the other end to my MightyVac gauge, revved the engine to about 1800-2000 rpm but got almost no vacuum.
This leads me to believe that the egr solenoid is not opening or there would be vacuum at this connection (that goes to the egr valve) if 12 volts is getting to the solenoid.

Test #3
I tried the same tests with my other egr solenoid (from my 86 GT) but the results were the same.
As I mentioned before, my 86 GT passed smog recently so I don’t know why both egr solenoids appear to be not opening.

Your thoughts?
Kit

[This message has been edited by Kitskaboodle (edited 09-24-2022).]

quote Originally posted by Kitskaboodle: I took off just the hose/line that goes out from the solenoid “T” junction nipple, (and goes to the egr valve) hooked up a separate vacuum hose to this nipple and ran the other end to my MightyVac gauge, revved the engine to about 1800-2000 rpm but got almost no vacuum.

Kit, you've probably already reported this, but there are a lot of posts to re-read, so...

To take the EGR solenoid out of the equation for a moment, what is the vacuum reading at 1800-2000 rpm at the end of the hose that goes into the solenoid from the throttle body? (...the red hose in the diagram below and/or the lower tube in the bottom image.)

[This message has been edited by Patrick (edited 09-24-2022).]

Kit, thank you for posting your test results. I should have time Sunday to compare to my last three tests. Also, my vac tester finally arrived so now I have no (good) excuse to continue avoiding this issue.

[This message has been edited by Notorio (edited 09-24-2022).]

quote Originally posted by Patrick: Kit, you've probably already reported this, but there are a lot of posts to re-read, so... To take the EGR solenoid out of the equation for a moment, what is the vacuum reading at 1800-2000 rpm at the end of the hose that goes into the solenoid from the throttle body? (...the red hose in the diagram below and/or the lower tube in the bottom image.)

I forgot to mention that I did the very test you are asking me to do but I didn’t post the results. Yes, I checked vacuum on the line that goes from the underside of the throttle body to the egr solenoid. (I tested it on the egr solenoid end) As a curious note, when the throttle body is completely closed, there is pretty much no vacuum but when you start to open the throttle butterfly, I start to get a good 8-10 hg of vacuum with only moderate rpm. So then, my egr solenoid is getting plenty of vacuum.

Seems to me the solenoid is NOT opening.
Is there another test / way to confirm my egr solenoid is not opening? Maybe I need to do a different test…
Kit

Cap the breather on the EGR Solenoid (the single vent tube that is pointing to the front of the car)
Then start and rev to 2k rpm and see if your EGR actuates. If it does not check the vacuum on it. If its still low or not actuating the EGR then your brass filters are probably plugged. Its also possible there is a burr or corrosion on the end of the tube inside the solenoid that the disk is suppose to seal against. If it cant seal pull flat and seal then even if its working it will never work.

Skywurz, thanks for the advice.
I think I am FINALLY making some progress!
As you instructed, I capped off (plugged) the filter end of the egr solenoid, (that takes in fresh air from the air cleaner) then I connected / teed in my vacuum gauge to the line just before the egr valve, warmed up the engine for about 3-4 minutes, then read the vacuum gauge at idle (zero) but then after increasing the rpm to about 1900-2000 rpm or more the vacuum gauge started to show 5-7 hg! 😀
It looks like we are getting close…..
Ar this point, I’m a little confused as to what is going on here. Yes, I now have sufficient vacuum at the egr valve but why did capping the fresh air coming in port solve the issue?? Maybe I should leave it capped at this point? Do I need this fresh air from the air cleaner?
By the way, because you also mentioned checking this, I did check the vacuum line coming in from the air cleaner (while revving the engine to 2K or so) and I got zero vacuum. I can see getting strong vacuum from the throttle body but how much vacuum are you supposed to get from a line that simply goes into the air cleaner canister?

Thanks, Kit

.

Kits

Capping the end that goes to the air cleaner bypasses the solenoids function. This has basically set the car up as the old school vac from the intake directly to the EGR. This test allows you to verify that the vacuum is all good with the system meaning the issue is with the solenoid its self. I had mentioned prior that perhaps your other GT has an obstruction in the air cleaner line and that's why that solenoid is also not working in this car. Capping the line can probably get you through smog as it will open the EGR under the test RPMs and you probably wont throw codes during the test. but you probably should not cap it where its easily seen. Basically you will probably suck more exhaust into the intake than typical this will reduce your NO but it wont be right. I suspect that either the flat plate is not sealing well against the air intake line or the magnet is too weak to pull it well. You could also have some sort of electrical or computer problem that just is not firing the solenoid.

[This message has been edited by skywurz (edited 09-26-2022).]

Thanks for the input.
I don’t think it’s the ECM as I already put in another one from an 85 SE V6 but there was no change. Also, I already verified that the lower two pin outs on the 4 pin connector are supplying 12+ volts to the solenoid when revving the engine to 1800 or more rpm’s.

Kit

I think Technically you can test how well the disk is sealing by removing the solenoid, capping the bottom tube with 2 outlets (for egr and pressure sensor) then blowing into the top tube.(The one that comes from the intake) If its sealing well you should get little to no leak going through the back tube (to the air filter). If it does leak you need to make sure there is no corrosion on the tube or burrs that the disk sits against. You also need to make sure you have oriented your spring correctly. (it should be in the cap side not the body side) you should have whiteness marks.

Since I was curious about the other egr solenoid from my 86 GT, I decided to take it apart also. Here is a pic of it filleted and the other showing the ohm reading of the coil winding. Does this reading seem correct?
Kit

looks good now apply 12v with it open like that and see if that metal disk will stick where its suppose to.

Sorry, I was a little to gung-ho and already put it all back together tonight. I did do the test you asked about though. I plugged the nipple that goes to the egr valve and sensor, then blew into the other nipple (toward the fresh air filter) and it seemed to hold tight. (No air leaking through)

On another note, since the original egr solenoid is back on the 85 and it doesn’t seem to be working on its own, I’m going to take it back off in the next day or two, take it apart and do the metal plate / applying 12 volts “suck off” test you are asking me to do.
Stay tuned… (and thanks for all your help!)
Kit

Ok, I did 3 more tests tonight on my original 85 GT egr solenoid:

Test #1 / I tested the ohm reading on the coil winding by probing the two lower pins on the egr solenoid 4 pin connector. (it was 95.8 ohms)

Test #2 / After taking the egr solenoid all apart, I held the coil winding assembly & its housing in a vertical position, (intake nipple straight up & the other end that contacts the spring and plate facing downward) then, while holding the
metal block off plate on the tip of my finger, I applied 12 volts to the solenoid. It pulled up the metal plate very strongly to block off the hole.

Test #3 / I reassembled the spring, plate & plastic end cap, (the one with twin tubes) I then applied 12 volts to the solenoid & tried to blow air into the egr solenoid through the intake nipple (incoming fresh air side) and could NOT
blow through until I disconnected the 12 volt power.

Kit

[This message has been edited by Kitskaboodle (edited 09-28-2022).]

That sounds promising. I cant think of any other reasons this should not work.

Ok, I did the same test again this evening but after fully reassembling the egr solenoid.
I applied 12 volts to the lower two pins of the egr solenoid and then tried to blow air from the fresh air intake side toward the other end of the egr solenoid. When I applied 12 volts, I was no longer able to blow air through the twin port tubes. It was “sealing “ (or blocking) the air very good.
Next step is to install the egr solenoid back on the car and see if it now works as it should.
Stay tuned! 😀
Kit

Ok, I put my egr solenoid back on my 85 GT, teed in my vacuum gauge to the egr valve, warmed up the engine, revved it to 1900-2000 rpm or so and noticed I’m still only getting 2.5 hg of vacuum at the egr valve. As you know, I have already verified that the egr solenoid is opening on command after applying 12 volts. To repeat a previous test, when I capped the intake side (fresh air side) of the egr solenoid, the vacuum got better. (4 to 4.5 hg)

At this point I’m still baffled by the low vacuum at the egr valve. What I would like is for someone to verify what vacuum they get at their egr valve when its open.
Anyone?
Thanks Kit

Kit, did you confirm that the ECM is sending 12v to the solenoid?

This afternoon I should be able to check my vacuum at the EGR valve and report in.

quote Originally posted by Kitskaboodle: 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 I was still not getting vacuum synthetic 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

0.0 ohms is a short, not an open.

Edit: somehow missed this was 2 pages and already mentioned...

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.

No pushrod 60V6 Fiero has been faster according to the 1/4 mile list.

[This message has been edited by ericjon262 (edited 10-07-2022).]

quote Originally posted by Notorio: I tried, but hardly saw any deflection on my new gauge. Does your gauge have finer gradation than this one? I doubt if I could reliably tell the difference between 2.5 and 4 in Hg.

I dug out my vacuum gauges which I haven't used... forever, and the graduation on them is a little finer than your gauge. With a 180° sweep, your gauge goes up to about 42 inHg. With a 180° sweep, my vacuum gauge goes to 26 inHg, and the built in gauge on my Mityvac II goes to 20 inHg with the same 180° sweep. So the gauge on the Mityvac II would appear to be the most accurate. However, I'm not 100% sure it would work when measuring vacuum from another source other than itself.*

I'll connect them to the 2.8 (with a fully functional EGR system) in my Formula tomorrow and report what readings I get.

[EDIT] I went back and re-read some posts, and came across this...

quote Originally posted by Kitskaboodle: I took off just the hose/line that goes out from the solenoid “T” junction nipple, (and goes to the egr valve) hooked up a separate vacuum hose to this nipple and ran the other end to my MightyVac gauge, revved the engine to about 1800-2000 rpm but got almost no vacuum.

* Kit, is your "MightyVac gauge" the same as what's pictured below (which is the same as my Mityvac II)?

[This message has been edited by Patrick (edited 10-07-2022).]

This is my vacuum gauge. (see pics)
Also, look at the open book pic. On the right side, number 3 it says 5 hg minimum in regard to required vacuum at the egr valve.
On a different note, thanks Notorio for the service manual pic. I did not notice that it says you are supposed to check the egr valve vacuum in DRIVE, press the brakes and then briefly rev it to 1800 rpm. (both of my Fiero’s are auto’s) Maybe I’m checking vacuum wrong???
Kit
[img]https://images.fiero.nl/userimages/Kitskaboodle/E57 939ED-73C5-4F27-BE69-840C4BDD7C34.jpeg[/img]

[This message has been edited by Kitskaboodle (edited 10-10-2022).]

quote Originally posted by Kitskaboodle: I took off just the hose/line that goes out from the solenoid “T” junction nipple, (and goes to the egr valve) hooked up a separate vacuum hose to this nipple and ran the other end to my MightyVac gauge, revved the engine to about 1800-2000 rpm but got almost no vacuum.

I've just come in after "T"ing my Mityvac II into the EGR vacuum line (at the valve) of my Formula. At idle, there was no discernible vacuum, as was expected. When I revved the engine (and the EGR solenoid activated), the vacuum went to a steady 2 inHg (on a scale that goes up to 30 inHg).

However...

Even though I was using my most "accurate" vacuum gauge (it has the finest graduation of the three gauges I own), I don't know how much credence can be given to my (or any of our) readings. IMO, these gauges are far too basic/inaccurate to be measuring such a low vacuum with any precision.

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.

Did you put your fingers on the underside of the EGR valve to see if it was moving/opening when you revved the engine?

My EGR valve was opening with a supposed vacuum reading of 2 inHg. It may be that you've been concerned about your "low" reading of 2.5 inHg for nothing.

[This message has been edited by Patrick (edited 10-14-2022).]

quote Originally posted by Patrick: Even though I was using my most "accurate" vacuum gauge (it has the finest graduation of the three gauges I own), I don't know how much credence can be given to my (or any of our) readings. IMO, these gauges are far too basic/inaccurate to be measuring such a low vacuum with any precision.

I second that conclusion.

quote Originally posted by Patrick: Did you put your fingers on the underside of the EGR valve to see if it was moving/opening when you revved the engine?

I'd like to point out that some of us have the 'new style' EGR. The genius who designed this made it impossible to SEE if the valve is actually working. If anyone knows a way to SEE if it is working, please let us know.

quote Originally posted by Notorio: I'd like to point out that some of us have the 'new style' EGR. The genius who designed this made it impossible to SEE if the valve is actually working. If anyone knows a way to SEE if it is working, please let us know.

Interesting. Now keep in mind, I didn't "see" my EGR valve working either... I felt it with my fingers.

I notice a small hole on the underside of the housing in your image. Could something non-pointy be inserted into that hole and gently positioned up against the diaphragm to feel for movement?

[This message has been edited by Patrick (edited 10-15-2022).]