Thank you guys for your questions as they are right in line with the questions I had!
First, I too had been wondering how to verify the egr valve is opening when you can’t get your finger in there to see if the diaphragm is moving upward. I believe the brand of egr valve I bought for my 85 is a “Standard”. If the one I bought has the same hole as the AC Delco in the above pic, I will test it tomorrow by inserting one of the common red plastic spray tube thingies that they always include with spray cans like Gumout, WD-40, various contact cleaners, etc. This should work, correct?
Secondly, from the beginning of my thread I had it in my mind that the MightyVac book was right and my Fiero egr valve was wrong. Meaning this: the book clearly said you have to have at least 5 hg for the egr valve to open and mine was/is barely showing half of that. So, I assumed it was not opening.
Lastly, through all of my testing/detective work, taking apart, cleaning & testing the egr solenoid, I feel that I didn’t really find any smoking guns. (other than the low vacuum at the egr valve)
What is confirmed for sure is that it did fail smog twice for high Nox and I have not taken it back to the smog shop since A) because I don’t think I have done anything to resolve the issue and B) because of the mismatch of the MightyVac books insistence on 5 hg at egr valve when in reality I never got more than 2.5 hg. Kit P.S. you guys didn’t comment on the service manuals instruction on checking egr valve vacuum while in DRIVE.
[This message has been edited by Kitskaboodle (edited 10-15-2022).]
Thank you guys for your questions as they are right in line with the questions I had!
First, I too had been wondering how to verify the egr valve is opening when you can’t get your finger in there to see if the diaphragm is moving upward. I believe the brand of egr valve I bought for my 85 is a “Standard”. If the one I bought has the same hole as the AC Delco in the above pic, I will test it tomorrow by inserting one of the common red plastic spray tube thingies that they always include with spray can like Gumout, WD-40, various contact cleaners, etc. This should work, correct?
Secondly, from the beginning of my thread I had it in my mind that the MightyVac book was right and my Fiero egr valve was wrong. Meaning this: the book clearly said you have to have at least 5 hg for the egr valve to open and mine was/is barely showing half of that. So, I assumed it was not opening.
Lastly, through all of my testing/detective work, taking apart, cleaning & testing the egr solenoid, I feel that I didn’t really find any smoking guns. (other than the low vacuum at the egr valve)
What is confirmed for sure is that it did fail smog twice for high Nox and I have not taken it back to the smog shop since A) because I don’t think I have done anything to resolve the issue and B) because of the mismatch of the MightyVac books insistence on 5 hg at egr valve when in reality I never got more than 2.5 hg. Kit P.S. you guys didn’t comment on the service manuals instruction on checking egr valve vacuum while in DRIVE.
For reference, here is a pic from my MightyVac book showing the requirement of 5 hg at the egr valve….(look at the right page, top left area) I also have to admit that I did not rev my engine to 3000 rpm like the book recommends to test egr valve vacuum but rather only 2000 or so. It seemed liked revving it any higher than 2000-2200 rpm didn’t change/raise the vacuum hg anyways. Kit
[This message has been edited by Kitskaboodle (edited 10-15-2022).]
P.S. you guys didn’t comment on the service manuals instruction on checking egr valve vacuum while in DRIVE.
I believe that's somewhat of a red herring, as how would it then ever be possible to check EGR valve vacuum on an engine in a car with a manual transmission (like my Formula)?
quote
Originally posted by Kitskaboodle:
It seemed liked revving it any higher than 2000-2200 rpm didn’t change/raise the vacuum hg anyways.
Yes... I was probably annoying my neighbors with some high revving in the driveway , and my readings never went above 2 inHg.
quote
Originally posted by Kitskaboodle:
First, I too had been wondering how to verify the egr valve is opening when you can’t get your finger in there to see if the diaphragm is moving upward. I believe the brand of egr valve I bought for my 85 is a “Standard”. If the one I bought has the same hole as the AC Delco in the above pic, I will test it tomorrow by inserting one of the common red plastic spray tube thingies that they always include with spray cans like Gumout, WD-40, various contact cleaners, etc. This should work, correct?
One thing I didn't think of trying at the time, was to connect the Mityvac directly to the EGR valve (with the engine not running) and applying more than 2 inHg vacuum (within reason, like maybe 5 inHg) to see if the EGR valve would actually open any further.
If you can get a probe inside the bottom of your EGR valve, maybe you can check to see whether additional vacuum (over what your engine normally seems to be applying to your EGR valve) makes any difference with the amount of diaphragm travel. If it doesn't, then you know for sure that there's no point worrying about your "low" vacuum reading.
[This message has been edited by Patrick (edited 10-15-2022).]
For additional reference, here’s a pic of the underside of my old 86 GT egr valve. I believe this one is also the “Standard” brand. Patrick, I will perform the tests you just mentioned and report back this afternoon. 😀 Kit
I did some testing today on the new egr valve on my 85 GT and also on my old egr valve from my 86 GT. (which is off the car and on my workbench) Per Patrick’s request I checked both egr valves manually by applying some vacuum to them and observing if the diagphram is opening. When I applied a good 3 or more hg, the valve would open. Anything less than 3 hg, it didn’t seem like it was really opening. Both valves behaved the same way with the same hg. Also, I could tell they were opening because when you suddenly released the vacuum, there would be a plop or dink. (it was going back to it’s closed position) As a side note, when I applied 5 hg, they would hold that vacuum for a while, only sinking down maybe to 4 hg.
Ok, after these tests I then went back and re-checked the vacuum again while teed in to the egr while the engine was warm. I revved it to 2200-2400+ rpm and for some reason I was now getting 4-5 hg on the vacuum gauge. So, I decided to go and do another re-test at the smog shop (since I was NOW) getting better vacuum TO the egr valve. Well, it failed again for the third time. ☹️ Here is a pic of the emissions test numbers. I noticed that it seems to be failing the 15 mph test but passing the 25 mph test. Your thoughts? Kit
[This message has been edited by Kitskaboodle (edited 10-15-2022).]
Just wanted to point out two things: 1st, I took my 85 GT to the smog shop for the 3rd time Saturday and it failed again with high Nox. 2nd, that being said, it failed twice at the lower speed (15 mph) at 1748 rpm. Maybe the egr is opening but not enough?? Kit
Years ago when we still had emission testing here, I had a helluva time trying to get my first Fiero, an '87 duke, to pass. After messing about with everything else and continuing to fail, I finally replaced the cat. Bingo.
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?
I fished out my mirror/light gizmo and can clearly see the diaphragm. It might be possible to do as you suggest.
EDIT - I just now saw Page 3! Yes, I have the same type as Kit.
[This message has been edited by Notorio (edited 10-17-2022).]
I've been scouring the Forum for recommendations on EGR and Smog testing. One of these is for 15 mph (use 1st gear) and 25 mph (use 2nd gear). I'm not sure about this yet: your test shop consistently ran 15 mph (1750s rpm) and 25 mph (1670s rpm). My tests were done at THREE different shops (because shop #2 especially didn't seem to know what he was doing -- he kept coming out to ask ME questions about the hook up!) Anyway, that guy ran at similar to your settings but the other two guys ran at around 15 mph (1574 rpm) and 25 mph (2600 rpm!) Both guys at Shop 1 and 3 seemed to know what they were doing. The reason I'm posting this is that I'm not sure Your car or My car are being tested correctly.
Patrick, my cat is a brand new, California certified cat. Not even 50 miles on it. EGR valve and O2 sensor are also brand new.
On a different note, I performed another test today that you all might find important: I decided to do a manual vacuum test on two Fiero V6 egr valves, one brand new and one that I removed from my 86 GT with about 10K-15K miles on it. Both egr valves were sitting on my workbench for this test. With my MightyVac vacuum gauge, I slowly applied vacuum to each egr valve. As I did this, I observed the pintle begin to retract upward. I noticed that it would travel upward as you applied more hg’s of vacuum. (yes, I know this is an obvious statement) Anyways, I determined that both egr valves were “fully opened” only after hitting about 5 1/2 to 6 hg. Less hg, less open, etc… The point is (and yes, I’m assuming here) that in order for the egr valve to allow exhaust gases to re-enter the egr tube/intake manifold, it has to significantly open for the whole egr process to work, correct? If so, my other point then is that the egr valve needs to get 5 hg of vacuum from a vacuum source. So maybe the MightyVac book reference of 5 hg minimum is correct. Kit P.S. I see Notorio’s point about going to a different shop but I had already paid them $50 even though it failed. Re-tests are only an additional $10 dollars. Kit
I determined that both egr valves were “fully opened” only after hitting about 5 1/2 to 6 hg. Less hg, less open, etc. The point is (and yes, I’m assuming here) that in order for the egr valve to allow exhaust gases to re-enter the egr tube/intake manifold, it has to significantly open for the whole egr process to work, correct?
I don't know if it would be correct to make that assumption. It's possible the EGR valve opens far enough to have the required effect at whatever "low" vacuum (within factory specs) is being directed to it by the EGR solenoid.
I do know for a fact that the 2.8 (or probably any engine) will not run properly if the EGR valve is “fully opened” at all times, as I experienced and reported Here.
Patrick, my cat is a brand new, California certified cat. Not even 50 miles on it ...
Kit
Kit, another recommendation I found was that New Cats should be run for at least 100 miles in order to fully burn off the protective coating they come with and that before 100 miles they won't be fully operational. Perhaps others will comment on if this is important or not.
I found this egr troubleshooting chart in my FSM. (see attached) In the top left area of the page there is an instruction to remove the double vacuum line that goes to the egr solenoid vacuum port nipple, then rotate it & reconnecting just the egr valve side, then hooking up a vacuum gauge to the manifold side egr port, (on the egr solenoid) then turn the ignition switch to ON, then apply vacuum and then egr valve should not open. Well, when I apply vacuum with the vacuum gauge and start pumping, it will not apply vacuum no matter how hard I pump the vacuum gauge. I did this same test on my 86 GT (which has no known egr problems) and the results were the same. Am I doing something wrong? Kit
While I was doing some additional testing, I reconfirmed (again) that A) the vacuum line that goes from the underside of the throttle body to the egr solenoid (manifold side) is good and has no leaks. I also reconfirmed that the vacuum line that goes from the egr valve to the egr solenoid (the port that has a tee junction on it) is good also and has no leaks. Kit
When you replaced your EGR valve did you replace the orifice plate? When I purchased a replacement for mine the instructions said something about matching the orifice plate to the engine. There were several orifice plates with different sized holes. I'm guessing they allow different amounts of exhaust to be recirculated which could change the emissions readings
Ok, I might have made some progress today. (Here’s why) There is a thread I saw here on the forum and it’s been on my mind. The thread raised the question about the egr tube gaskets as far as which one goes on the plenum side and which one goes on the egr valve side. As you may know, one has a restriction and one doesn’t. Just to confirm, I called Steve at the FieroStore and he said the gasket that has the smaller opening goes on the intake manifold side and the bigger opening gasket goes on the egr valve side. So…… because I recently put on a new egr valve, I recall doing the opposite. I took my egr tube off and yes, I can confirm I put the smaller opening gasket on the egr valve side. Here is a pic of the parts on my workbench in just the order I put the egr tube on. Kit
[This message has been edited by Kitskaboodle (edited 10-31-2022).]
To further ponder on this smaller orifice gasket… I did order some extra egr tube gaskets from Rockauto and they are the “normal” big hole version. (See pic) So, where do you get this special smaller orifice hole version? What if I ran both sides with the bigger, normal gaskets? Maybe this might fix my high Nox issue? Any Calif. guys run both ends that are the normal size? (No orifice restrictions) Kit
As a side note, I had not really focused on my pcv valve in a long time. I took it out today and found out that, though it would rattle when shaked, it was quite gummed up and I could still blow a little air through it. Shame on me for overlooking this. I ordered two tonight.. Kit
, and my readings never went above 2 inHg.
