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High NOx Smog Failure (Defeat or Bust) by Notorio
Started on: 02-11-2023 01:58 PM
Replies: 80 (1042 views)
Last post by: Notorio on 05-02-2023 11:43 PM
Notorio
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Report this Post03-18-2023 07:10 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by sanderson231:

Given that the vacuum source is ported the vacuum will depend on the position of the butterfly. The butterfly position while revving the engine to 1800 rpm in neutral vs driving down the road with the engine at 1800 rpm will be different The factory service manual does say when doing the 1800 rpm test to "have the engine in drive (automatic transmission), hold brake, accelerate momentarily to 1800 rpm and observe gauge". I'd suggest hooking a gauge with a long hose to the EGR port on the TB and taking the car for a drive while observing the gauge.

If it passes an 1800 rpm test, I would remove the top intake to inspect the EGR tube and where it enters the tube attaches to intake manifold to make sure that it is not grimed up.

Still curious that GM used ported vacuum when the ECM is using pulse width modulation to control the EGR solenoid)




Towards Patrick's good point, this new vacuum gauge just allowed me to retest when the EGR opens enough to cause the idle to stumble. Using my manual pump, teed into the line, with repeated trials, I'm convinced my EGR doesn't crack open until 3" on the gauge (whatever the 'absolute' inches of Hg might actually be.) The ported vacuum on the TB at 1800 rpm, now that I opened up the orifice to 0.075" (from 0.059"), is now a solid 1" instead of just barely moving the needle. There is no question whether this would open my EGR ... it will NOT.

Toward's Sanderson's good point, that is true the FSM calls for an automatic to be in gear and on the brakes. It DOES make sense that the throttle plate would be more open to accomplish that, and that the ported vacuum would therefore be higher. Instead of driving, can I do this with the wheels off the ground, since I have a manual?

Second point: when I had the EGR tube off I looked into the EGR port and it looked fine.

QUESTION: Before I try the road test with the really long vacuum tube, does anyone know what the California Smog test calls for at the two speeds? I had found that info but now can't find it again. I may have to call BAR to get a definitive answer. The reason I ask is because the three shops I've been too are not all doing it the same way.

For 15 mph test, use 1st gear, engine about 1600 rpm

For 25 mph test, use 2nd gear, engine about 2500 rpm
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Report this Post03-18-2023 07:43 PM Click Here to See the Profile for sanderson231Send a Private Message to sanderson231Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:
Toward's Sanderson's good point, that is true the FSM calls for an automatic to be in gear and on the brakes. It DOES make sense that the throttle plate would be more open to accomplish that, and that the ported vacuum would therefore be higher. Instead of driving, can I do this with the wheels off the ground, since I have a manual?


Maybe, if you applied some brake while revving engine up. You need to put some load on the engine to get the butterfly to open up. I would trust a road test more.

You could road test two ways; 1) with vacuum gauge connected to throttle body to make sure that you have enough source vacuum and 2) with vacuum gauge teed into vacuum line between the EGR solenoid and the EGR valve. The second test would verify functioning of EGR solenoid under control by the ECM.

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Report this Post03-19-2023 10:34 AM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by sanderson231:

Maybe, if you applied some brake while revving engine up. You need to put some load on the engine to get the butterfly to open up. I would trust a road test more.

You could road test two ways; 1) with vacuum gauge connected to throttle body to make sure that you have enough source vacuum and 2) with vacuum gauge teed into vacuum line between the EGR solenoid and the EGR valve. The second test would verify functioning of EGR solenoid under control by the ECM.



I'll do these tests once I understand the mph/gear question.

Found the BAR manual on line here.
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Report this Post03-19-2023 11:15 AM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post

Notorio

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So, the BAR manual refers to specific vehicle/engine parameters that their system communicates to the Smog Test Machine, including the RPM limits for the test. It calls out testing manual transmissions in 2ND GEAR but allows for choosing higher/lower gears to satisfy the RPM Range. Therefore, I will have to call BAR and get an appointment with a Referee to get the RPM range

Meanwhile, I discovered it is easy to carefully drill out the broken-off plastic tubing from the Rubber Elbow, using a 5/32" drill for this instance. The elbow then fits smoothly onto the remaining tubing and a little non-hardening gasket sealer makes a nice seal.


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Report this Post04-01-2023 12:37 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update - finally able to run the road test. Below is my setup with the gauge in the cockpit. Drum roll please ....

25 mph, 2nd gear, level road, gauge teed into the EGR value. The vacuum is at most 2 inches.

25 mph, 2nd gear, level road, gauge directly to EGR port on the TB. The vacuum is about 10 inches.

Since from prior tests I know my new, new-style EGR doesn't open until 3 inches, this proves the EGR doesn't open during the Smog Test. The Root Cause would appear to be Too High of a 'Pressure Drop' inside the EGR Solenoid. How to fix THAT seems like the next challenge and more reading on the Forum.

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Report this Post04-01-2023 01:15 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post

Notorio

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Here is an excellent thread started in 2004 with posts out to 2020. Page 1 has all the info to troubleshoot a non-functional EGR Solenoid. Click Here I'm using this as my guide to take apart and look for perhaps weak opening against the spring or dirt buildup, etc.
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Report this Post04-01-2023 01:28 PM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:
...
Since from prior tests I know my new, new-style EGR doesn't open until 3 inches, this proves the EGR doesn't open during the Smog Test. The Root Cause would appear to be Too High of a 'Pressure Drop' inside the EGR Solenoid. How to fix THAT seems like the next challenge and more reading on the Forum.



Edit - Your post beat me to it.
=========================

Okay. In this case "Pressure Drop" pretty much = "Vacuum Leak"

Thje EGR valve works by venting ported vacuum to the atmosphere, when it's not commanded "on". This is the little nipple on the front end of the EGR solenoid.
Blocking that nipple should provide maximum vacuum to the EGR valve. Period. Unless there is a leak somewhere else.
Easy enough to test (or possibly to "gimmick" the solenoid by putting a BB in a hose, attached to that nipple. Nudge, nudge. Same thing as running a hose straight from the TB to the EGR valve.)

Or it's possible that your EGR solenoid is just failing.

I'll remind you of the recall "fix". There used to be a rubber hose that connected that nipple on the EGR solenoid to a tube on the firewall. That tube extended over to the air filter. It was sucking air, but it was filtered air. Many times, those hoses just got removed.

[This message has been edited by Raydar (edited 04-01-2023).]

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Report this Post04-01-2023 01:55 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

A. Okay. In this case "Pressure Drop" pretty much = "Vacuum Leak"

B. Thje EGR valve works by venting ported vacuum to the atmosphere, when it's not commanded "on". This is the little nipple on the front end of the EGR solenoid.
Blocking that nipple should provide maximum vacuum to the EGR valve. Period. Unless there is a leak somewhere else.
Easy enough to test (or possibly to "gimmick" the solenoid by putting a BB in a hose, attached to that nipple. Nudge, nudge. Same thing as running a hose straight from the TB to the EGR valve.)

C. Or it's possible that your EGR solenoid is just failing.

I'll remind you of the recall "fix". There used to be a rubber hose that connected that nipple on the EGR solenoid to a tube on the firewall. That tube extended over to the air filter. It was sucking air, but it was filtered air. Many times, those hoses just got removed.



Raydar, thanks for thinking about my little problem. I've got the Solenoid partially apart now and am leaking at possible leaks (Point A). The hoses to/from were previously checked and found NOT to leak.

As for Point B, the function of the complete system is still a bit mysterious to me. I suspect if I try to block that filtered-air inlet, the EGR Valve will OPEN and then remain open, regardless of the position of the Throttle Plate. Not sure about that, however.

As for Point C, I can't get the solenoid coil out of the housing. I've pulled and pushed as much as I dare. Is there a trick to this? Posting a picture of what that looks like below.


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Report this Post04-01-2023 02:00 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post

Notorio

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Here's something interesting. The relatively large diameter hosing coming from the TB Port and going to the EGR Solenoid has an orifice in it that is TINY. Take a look below, the nipple on the Left. There is no Brass Filter that I can see. One thought I had was to enlarge this TINY hole a bit ...



Another idea would be to snip a coil off this spring to make it easier to open ...

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Report this Post04-01-2023 04:42 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post

Notorio

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quote
Originally posted by Notorio:

As for Point B, the function of the complete system is still a bit mysterious to me. I suspect if I try to block that filtered-air inlet, the EGR Valve will OPEN and then remain open, regardless of the position of the Throttle Plate. Not sure about that, however.



Eureka! Raydar, you were right! I plugged the filtered-air inlet as suggested and now I'm getting 10 inches at 25 mph! Let off the throttle and the vacuum returns immediately to zero.
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Report this Post04-01-2023 05:15 PM Click Here to See the Profile for sanderson231Send a Private Message to sanderson231Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:


Here is an excellent thread started in 2004 with posts out to 2020. Page 1 has all the info to troubleshoot a non-functional EGR Solenoid. Click Here I'm using this as my guide to take apart and look for perhaps weak opening against the spring or dirt buildup, etc.


This sounds to me like the "block-off" plate inside the EGR solenoid as referenced in the above thread is not sealing well. It is allowing an air leak while the EGR is commanded on that is breaking the vacuum that is supposed to go the EGR valve. Air should only get by the block-off plate when the EGR is commanded off. The ECM will cycle the solenoid on and off to control the EGR duty cycle.

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Report this Post04-01-2023 05:20 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
If I fully understand some of the previous posts up the page, there seemed to be a suggestion that there needed to be a load on the engine for the EGR valve to actually activate/open. In my experience, this is not necessary. I was doing some work on my Formula a few days ago, and while I was thinking about it, I felt the underside of my EGR valve diaphragm with a finger while I revved the engine (with 5-spd out of gear, no load on engine). It didn't take much revving at all for the diaphragm to start opening... and that's with the vacuum readings earlier reported below. This may or may not still be relevant to the discussion, but I figure the more info the better.

 
quote
Originally posted by Patrick Here:

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 Notorio:

One thought I had was to enlarge this TINY hole a bit ...

Another idea would be to snip a coil off this spring to make it easier to open ...



IMO, both very bad ideas!

 
quote
Originally posted by sanderson231:

This sounds to me like the "block-off" plate inside the EGR solenoid as referenced in the above thread is not sealing well.


I agree. This seems like the proper avenue to explore!

I wonder if there's a chance that EGR solenoids missing the rubber tube (pictured below) for any extended period of time might've sucked in enough unfiltered air to muck up the seal for the block-off plate inside the solenoid?

 
quote
Originally posted by buddycraigg:

The fresh air port on the back of the solenoid is suppose to have a hose that goes to this metal line on the firewall.



[This message has been edited by Patrick (edited 04-01-2023).]

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Report this Post04-01-2023 05:58 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
I agree with both of you ... a poor seal on the block off disk. Except that cleaning it didn't help.

So, currently I'm sitting in the smog station while they run the test. Fourth time's a charm? On April Fool's Day?? I have the air inlet blocked, hoping that this subtle mod passes muster. The CARB diagram doesn't have THAT line going anywhere so I surmised this would be low risk.
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Report this Post04-01-2023 06:03 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post

Notorio

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PASS. Only 130 ppm NOx.
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Report this Post04-01-2023 06:36 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:

So, currently I'm sitting in the smog station while they run the test. Fourth time's a charm? On April Fool's Day??


 
quote
Originally posted by Notorio:

PASS. Only 130 ppm NOx.


So... are you joking with us?

If not, what does this result tell us? If the EGR solenoid fresh air port wasn't required in the first place, it wouldn't be there. Passing the smog test by blocking this port is fine, in regards to getting the nuisance test out of the way... but what is this actually telling us? What have we learned about the EGR system, and it's inability to to open the EGR valve (on this particular engine) without drastic measures? And what is the downside if the fresh air port is left plugged to allow the EGR valve to continue to function?

[This message has been edited by Patrick (edited 04-01-2023).]

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Report this Post04-01-2023 06:55 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

So... are you joking with us?


Happily, the answer is NO. It actually PASSED with a mere 130 ppm NOx at both 15 and 25 mph. They ran in 2nd gear. I was actually mentally prepared to have it FAIL again because I didn't believe that the Exhaust Gas that flows through an 8 mm opening into the Intake Manifold would do much of anything. So I'll leave my little plug in place and be Less Polluting, happily ever after. Next week, time to stand in the line at the DMV, then hope and pray that the paperwork gets straightened out without undue cost and frustration.

FOR FUTURE READERS: I really think the internal leak, inside the EGR Solenoid is the culprit. Perhaps I needed to dress the rim that the washer seals against but I didn't want to bend back the metal tabs a second time, figuring they'd give up the ghost. In my case, the 2 inches of vacuum wouldn't open the EGR valve whereas for you it might be fine. Several people have reported 2 inches works for them.
In any event, with the little vacuum plug in place on the air inlet, the EGR will open any time the throttle plate starts to open. All's well that ends well.
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Report this Post04-01-2023 07:25 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
Notorio, I don't know if the paragraph I added to my previous post was there when you last responded.

 
quote
Originally posted by Patrick:

What does this result tell us? If the EGR solenoid fresh air port wasn't required in the first place, it wouldn't be there. Passing the smog test by blocking this port is fine, in regards to getting the nuisance test out of the way... but what is this actually telling us? What have we learned about the EGR system, and it's inability to to open the EGR valve (on this particular engine) without drastic measures? And what is the downside if the fresh air port is left plugged to allow the EGR valve to continue to function?



I'm curious... When you disassembled your EGR solenoid, did you find a foam rubber "filter" (mentioned previously in the forum) inside of the fresh air port? I don't know it's density, but I wonder if it's possibly not so much just a filter, but maybe also a restriction for the air flow... a restriction that you've now accomplished (albeit more so) through other means. I'm just thinking out loud here, and I might be totally out in left field.

[This message has been edited by Patrick (edited 04-01-2023).]

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Report this Post04-01-2023 07:57 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is the only filter I saw, the one on the Sensor, which was completely disintegrated. This picture below is from the BuddyCraig post I linked in earlier.

I was not able to get the solenoid completely apart so I don't know if there is another filter hiding in there. I haven't found the post with a picture of that. Do you know which one it is?


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Report this Post04-01-2023 08:11 PM Click Here to See the Profile for sanderson231Send a Private Message to sanderson231Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

If I fully understand some of the previous posts up the page, there seemed to be a suggestion that there needed to be a load on the engine for the EGR valve to actually activate/open. In my experience, this is not necessary. I was doing some work on my Formula a few days ago, and while I was thinking about it, I felt the underside of my EGR valve diaphragm with a finger while I revved the engine (with 5-spd out of gear, no load on engine). It didn't take much revving at all for the diaphragm to start opening... and that's with the vacuum readings earlier reported below. This may or may not still be relevant to the discussion, but I figure the more info the better.




Because the vacuum source for the EGR soldenod is ported, the TB butterfly has to be somewhat open to get enough vaccum to open the EGR valve. If the rpms are raised to 1800 rpm in neutral there won't be much vacuum available because the butterfly doesn't have to open much to achieve 1800 rpm with no load. This relates to the FSM test that says there is supposed to be 2-10 " Hg vacuum at 1800 rpm. That test is supposed to be done with some load on the engine. This was proved by the road test that showed 10"Hg of ported vacuum available at 25 mph. The no load test at 1800 rpm showed much less - less than 2" IIRC. Blipping the throttle open will created some ported vacuum and get the EGR to move.

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Report this Post04-01-2023 08:25 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by sanderson231:

Blipping the throttle open will created some ported vacuum and get the EGR to move.


"Blipping the throttle open" can mean different things to different people. For some, that might mean redlining the engine for a brief moment. However, I'd like to make it clear that my EGR valve begins to open at the very slightest opening of the throttle while briefly revving up to maybe 2500 RPM.

 
quote
Originally posted by Notorio:

I was not able to get the solenoid completely apart so I don't know if there is another filter hiding in there. I haven't found the post with a picture of that. Do you know which one it is?


I'll poke around and see if I can find an image of this EGR solenoid foam filter.
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Report this Post04-01-2023 09:46 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

Patrick

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quote
Originally posted by Patrick:

What does this result tell us? If the EGR solenoid fresh air port wasn't required in the first place, it wouldn't be there. Passing the smog test by blocking this port is fine, in regards to getting the nuisance test out of the way... but what is this actually telling us? What have we learned about the EGR system, and it's inability to to open the EGR valve (on this particular engine) without drastic measures? And what is the downside if the fresh air port is left plugged to allow the EGR valve to continue to function?


While looking for info regarding the EGR solenoid filter, I came across this fairly recent post which basically answers most of what I was asking above.

 
quote
Originally posted by skywurz Here:

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.

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Report this Post04-01-2023 10:20 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

I came across the following video which is pretty good. It's a Fiero EGR solenoid that he's demonstrating with.

How To Rebuild & Repair An EGR Solenoid

I grabbed a screenshot of the camera looking down into the solenoid filter assembly. It almost looks like we can see out the other end, but that's not possible, as the rubber tube is still attached. I suspect we're seeing a reflection off something shiny down there (from the overhead light the fella is using for his camera). It appears that this "filter" is a bit more complicated than just a piece of foam rubber.



After looking at many EGR solenoid threads, and this video, I'm beginning to wonder if the sealing plate is not making a good seal "simply" because the entire housing itself isn't sealed well enough. Any vacuum loss would result in the sealing plate not being being sucked hard enough against whatever it is that it's supposed to seal against. (I'm getting tired... is the electric solenoid supposed to seal or unseal that plate?) Maybe I'm going wacky from looking over too much of this stuff today.
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Report this Post04-02-2023 11:21 AM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
Great video! Thanks for posting that, Patrick. That is one sad looking solenoid he was able to rebuild. He didn't mention anything about cleaning the disk and mating surface, nor did he clean the o-ring and where that seals. I think we can all see now that small leaks inside that device will greatly reduce the vacuum available to the EGR valve itself.

Can anyone chime in on the long-term effect of leaving the plug on the inlet?

Also, has anyone successfully bent back those metal tabs more than once?
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Report this Post04-02-2023 05:08 PM Click Here to See the Profile for sanderson231Send a Private Message to sanderson231Edit/Delete MessageReply w/QuoteDirect Link to This Post
If the EGR solenoid cannot be fixed another option would be to add a normally open solenoid valve to the vent. Wire it in parallel with the EGR solenoid. It would close when the EGR opens and vice versa. A cruise control vacuum release solenoid might work.

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Report this Post04-02-2023 10:18 PM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:


Happily, the answer is NO. It actually PASSED with a mere 130 ppm NOx at both 15 and 25 mph.


Excellent! Happy to hear it.

You might experiment with "calibrated leaks". What you've got now is essentially bypassing the solenoid, completely.
Start with a needle hole in the fitting. Move up a bit, gradually, and see what happens. Or not. Your call.
Pay attention to your gas mileage and... etc. Too much EGR can cause a loss of power, or even a misfire.
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Report this Post04-06-2023 07:03 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

Excellent! Happy to hear it.

You might experiment with "calibrated leaks". What you've got now is essentially bypassing the solenoid, completely.
Start with a needle hole in the fitting. Move up a bit, gradually, and see what happens. Or not. Your call.
Pay attention to your gas mileage and... etc. Too much EGR can cause a loss of power, or even a misfire.


Thank you, Raydar. It is a RELIEF to finally have the certificate in my hot little hand. I may tinker with it further, or might just remove the plug and forgot about it until Next Time.

Since it has been more than 12 months since I started the DMV saga, I am not eligible to use the on-line system, or to book an appointment for an in-person visit. My only options were to go stand in the non-appointment line for hours OR to patiently follow every link on line until I discovered there is a SPECIAL On-line application process for cars ineligible to the normal one. TO MY AMAZEMENT, after uploading various documents, and reacting to more demands, I have just progressed to the 'payment' stage, which I took to be a good thing. Perhaps I am just a few days away from being able to drive my baby again, after FOUR years off the road.
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Report this Post04-10-2023 07:30 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
BEWARE Californians. Don't use the on-line renewal, go in person. I ASSUMED that once the application was approved, the system would cough up a Temporary Registration form/email to print out and place in the window, but no dice. Just received an email saying I won't receive my documents for 21 Business days. It 'closes' the case so you can't reply back to the email anymore. The on-line chat bot is useless.
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Report this Post04-10-2023 09:32 PM Click Here to See the Profile for KitskaboodleSend a Private Message to KitskaboodleEdit/Delete MessageReply w/QuoteDirect Link to This Post
Notorio, are you ready for this?
Are you sitting down?
Is your seat belt fastened?
Just this morning I read this thread, (I hadn’t been on here in a while) heard what you did to make it pass, so I did the same exact thing, took my car down to the smog shop this afternoon and…..it passed!! 😀
In fact, not only did it pass but the Nox is really low at 15 mph and at 25 mph it’s ZERO! 😀

I thought about doing this “mod” a while back but after reading some threads on the internet (non-Fiero) about the consequences of the egr being open all the time, I was afraid to do it. After reading your post above, I decided to do a two-fold experiment: A) plug the inlet side of the egr solenoid to see if mine would pass like yours and B) I wanted to observe how the engine would behave on the 5 mile trip to the smog shop and on the way back to my house.
Driveability result? My 85 GT drove “fine”. Idled ok, good power, no hesitation, even water temps, etc. This was in stop and go city driving so I never got it up to highway speeds.
So, my next plan is to take it out next weekend for a highway cruise to see how it behaves then in this environment. And yes, I will keep an eye on gas consumption.
In the meantime, here are my smog results….
Kit
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Report this Post04-10-2023 09:47 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Kitskaboodle:

I thought about doing this “mod” a while back but after reading some threads on the internet (non-Fiero) about the consequences of the egr being open all the time, I was afraid to do it.


It would be interesting to know when and how much the EGR valve is open with this mod... as I can pretty well guarantee that it isn't open all the way all the time.

I found out and reported HERE that an engine doesn't run very well if that's the case!
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Report this Post04-10-2023 09:54 PM Click Here to See the Profile for sanderson231Send a Private Message to sanderson231Edit/Delete MessageReply w/QuoteDirect Link to This Post
Like I said earlier, if the EGR soleboid is leaking air and can't be fixed just put a solenoid valve on the vent line so that it is blocked when the ECM is trying to open the EGR valve.

------------------
formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
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Report this Post04-10-2023 11:38 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by sanderson231:

Like I said earlier, if the EGR soleboid is leaking air and can't be fixed just put a solenoid valve on the vent line so that it is blocked when the ECM is trying to open the EGR valve.



This sounds like the ultimate fix to me, however, it won't fly with CA Smog visual inspection, at least, it is a risk that it would be spotted if not properly camouflaged. My plan for my particular car is to remove the cap, that is, 21 business days from now when my registration arrives.

KIT, way to go! Congratulations on passing with flying colors!!
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Report this Post04-17-2023 05:29 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
UPDATE! Much to my surprise, after the dour DMV warning of 31 days, the Registration and Sticker arrived in the mail on Saturday! I put the sticker on the plate and turned the key, with visions of spritely driving dancing in my head, then, click, click. The battery was now 'dead as a doornail.' Fast forward to Monday and after a trip to O'Reilly's Auto to get a new battery ($$$), as was FINALLY able to hit the road (legally) and drive my baby.

Here's the license plate, sporting the new Year sticker.



And here's my trip to a local winery just to prove I can go somewhere other than DMV or the Smog Test Station.



And my seat-o-pants meter definitely says the port/polishing of the heads and the 1.6 rockers and the rings woke up the motor.

[This message has been edited by Notorio (edited 04-17-2023).]

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Report this Post04-17-2023 07:07 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Notorio:

And here's my trip to a local winery just to prove I can go somewhere other than DMV or the Smog Test Station.


Careful now, or you might end up bussing it for awhile.
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Report this Post04-22-2023 05:27 PM Click Here to See the Profile for KitskaboodleSend a Private Message to KitskaboodleEdit/Delete MessageReply w/QuoteDirect Link to This Post
Deja Vu Notorio…..
My Ca. plate is also Oct. 2023. 😀
Oh, and I’m a little envious of that color.
There’s a similar but lighter yellow color I want to paint my 85 GT.
On another note, PLEASE report back on engine driveability issues if you choose to leave the input side plugged. The only difference is that you have a manual and both my Fiero’s are autos.
Kit
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Report this Post04-22-2023 11:52 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Kitskaboodle:
Deja Vu Notorio…..
My Ca. plate is also Oct. 2023. 😀 ...


Our cars are in synch. Hopefully they will pass again in Oct 2024!

 
quote
Originally posted by Kitskaboodle:
Oh, and I’m a little envious of that color.
There’s a similar but lighter yellow color I want to paint my 85 GT ...


I really like that Yellow too but I wish I knew what Yellow it is! Several possibilities have been suggested to me and I've bought the test paint for 4 or 5 different Yellows but so far, no dice. It went to a paint shop once and asked if they would tell me what color it was and they wouldn't help me. It's a shame because I'd like to do some touch up until I can afford repainting. (A clutch, struts, shocks, and tires are ahead of Paint on the list.)

 
quote
Originally posted by Kitskaboodle:
On another note, PLEASE report back on engine driveability issues if you choose to leave the input side plugged. The only difference is that you have a manual and both my Fiero’s are autos ...


Too late, I already removed it. Perhaps YOU can make the report instead??
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Report this Post04-23-2023 07:00 PM Click Here to See the Profile for KitskaboodleSend a Private Message to KitskaboodleEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok, I will.
I plan on leaving mine plugged as long as my engine runs good.
I still need to do a shakedown test. I will try to do that tomorrow.
Stay tuned…….Kit
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Report this Post04-24-2023 08:33 AM Click Here to See the Profile for reinhartSend a Private Message to reinhartEdit/Delete MessageReply w/QuoteDirect Link to This Post
Interesting results here. One trick I've learned is if your car is passing everything but the NOX (usually almost always will pass HC with a new cat unless you got a major problem), just have them test the car cold. Drive it down, shut it off and tell them to leave the car off until it's ready to test (They'll always want to let the car idle in the bay like they're doing you a favor and helping you pass). It might reduce HCs but since that's never a problem with me, all they're doing is raising my NOX levels.

This strategy has worked for me countless times after having the same NOX issue as the OP and going through all of the troubleshooting and testing vacuum at idle and various RPMs. Remember, NOX is just produced from extremely high combustion temps. A cold engine won't see high enough temps to trigger NOX failure IME.

The seal off of the inlet is a new one but since I've already got a working system (See above), I'll probably stick with that until I get a failure with my method.
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Report this Post04-30-2023 06:19 PM Click Here to See the Profile for KitskaboodleSend a Private Message to KitskaboodleEdit/Delete MessageReply w/QuoteDirect Link to This Post
As promised, I did a mild “shake down test” today. Since this is the first real drive since I got it smogged, I didn’t want to drive it a long distance from home just in case the engine started behaving badly. (since I still have the intake port tube of the egr solenoid plugged)

Anyways, the run was mostly freeway cruising, about 65 most of the time. I drove approximately 35-40 miles total, which included a detour off highway 280 to go up into the hills. (Sand Hill Road up to Old La Honda Road and back on Alpine Road) Weather was about 68 degrees most of the trip. As an fyi I did not drive the car hard during this trip. (I drove like a “normal” person) 😀
I’m summary, the car drove absolutely fine. No idling issues at stoplights, no acceleration or hesitation issues, no overheating, nothing.
Granted, it might have been a more “telling” summary if it were 80-90 degrees out (and I drove with a lead foot) but that will have to come later during the summer.
Comments? Kit

[This message has been edited by Kitskaboodle (edited 04-30-2023).]

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Report this Post04-30-2023 06:26 PM Click Here to See the Profile for KitskaboodleSend a Private Message to KitskaboodleEdit/Delete MessageReply w/QuoteDirect Link to This Post

Kitskaboodle

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Member since Nov 2004
As promised, I did a mild “shake down test” today. Since this is the first real drive since I got it smogged, I didn’t want to drive it a long distance from home just in case the engine started behaving badly. (since I still have the intake port tube of the egr solenoid plugged)

Anyways, the run was mostly freeway cruising, about 65 most of the time. I drove approximately 35-40 miles total, which included a detour off highway 280 to go up into the hills. (Sand Hill Road up to Old La Honda Road and back on Alpine Road) Weather was about 68 degrees most of the trip. As an fyi I did not drive the car hard during this trip. (I drove like a “normal” person) 😀
I’m summary, the car drove absolutely fine. No idling issues at stoplight, no acceleration or hesitation, no overheating, nothing.
Granted, it might have been a more “telling” summary if it were 80-90 degrees out but that will have to come later during the summer.
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Report this Post05-02-2023 11:41 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by reinhart:
...

This strategy has worked for me countless times after having the same NOX issue as the OP and going through all of the troubleshooting and testing vacuum at idle and various RPMs. Remember, NOX is just produced from extremely high combustion temps. A cold engine won't see high enough temps to trigger NOX failure IME.

...



This is good to keep in our back pockets for Next Time. This makes me wonder if running a lower temp thermostat would also help??
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