Egr Solenoid Rebuilding? (Page 3/10)
Kitskaboodle AUG 26, 09:53 PM
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
skywurz AUG 26, 11:32 PM
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.
Kitskaboodle AUG 27, 10:04 AM
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. 😀
Kitskaboodle AUG 27, 11:29 PM
Ok, here is what I did this afternoon:

I checked the two elbows that go underneath the throttle body (for cracks, loose connections) but they seemed fine.

I checked the hoses & elbows that go to the egr solenoid. (they looked good and tight)

I did a vacuum test on the hose/plastic hard line that goes from the egr solenoid to the egr valve. What I did was I pulled off the vacuum hose that plugs in to the egr, capped it shut, then I disconnected the other side of this same line (that goes to the egr solenoid) then I applied about 8 hg of vacuum and it held tight and solid.

Even though the egr valve is brand new, I decided to check its operation. With the engine off, I applied 8 hg of vacuum to the egr valve and it held. (it did not leak down after 5-6 seconds or so.

Lastly, I checked the vacuum again at the egr valve (with the engine running and fully warm) and it is still barely reading 2.5 hg.

Kit
Mike in Sydney AUG 28, 01:52 AM
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?

Kitskaboodle AUG 28, 09:34 AM
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
armos AUG 28, 01:53 PM
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).]

Patrick AUG 28, 04:53 PM

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.
skywurz AUG 28, 07:30 PM

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.
Kitskaboodle AUG 28, 11:09 PM
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