Hi All,

Working on my high NOx issue (88GT, 5spd). I took the EGR tube OFF to confirm that the gasket with the #11 orifice was installed correctly, that is, on the intake side, not the EGR side. Sadly, it WAS correctly installed. I have two replacement gaskets at present and the hole size is different: one is 6 mm and the other is 7 mm. Does anyone know what the #11 size is??

John

One other thing: I was surprised that some oily liquid was collecting on the gasket on the intake manifold side. My first thought was perhaps my pretty-new PCV valve was at fault. Thoughts?

quote Originally posted by Notorio: Hi All, Working on my high NOx issue (88GT, 5spd). I took the EGR tube OFF to confirm that the gasket with the #11 orifice was installed correctly, that is, on the intake side, not the EGR side. Sadly, it WAS correctly installed. I have two replacement gaskets at present and the hole size is different: one is 6 mm and the other is 7 mm. Does anyone know what the #11 size is?? John

Good old Rodney. He confirmed for me that the size is 6 mm.

I'd still like to hear people's thoughts on the oily fluid ...

It could be that you have some blowby and it's being pulled in through the metal tube that runs to the intake snorkel at the throttle body. Check the rubber intake snorkel to see if you have oil there. Most intakes I've ever removed had a good heavy coating of black oily substance inside.

Pic provided for reference only. ( if this helps) (see attached pic below)
As an additional fyi, I had the small orifice egr tube gasket on the “wrong” end. (egr valve side)
Even after correcting this, my Nox numbers were still about the same. (I took it to get smogged again because I thought this was the culprit but it failed again with pretty much the same Nox numbers.
Kit

Man, now I'm confused. I was going to order gaskets for my EGR system, and it looked simple enough, but if I'm understanding correctly, each end of the EGR tube has a different gasket.

And the valve assembly has a couple of different gaskets available? There's one with tiny holes, and one without, the body shapes are different...

I believe the EGR Gasket has two different gasket is because there is a “spacer” block between the ear and the exhaust pipe.
I’m not sure why it makes a difference which end the smaller one with the restriction goes

quote Originally posted by PhatMax: I believe the EGR Gasket has two different gasket is because there is a “spacer” block between the ear and the exhaust pipe. I’m not sure why it makes a difference which end the smaller one with the restriction goes

Seems that Rock Auto only offers the one with the larger hole for the tube.

Where is everyone finding their gaskets?

edit - better yet, are there alternatives? We cobble stuff together all of the time, like using VW exhaust gaskets on the manifolds. Are there any gaskets that are "close enough" in terms of size of tube, and spacing of the holes?

[This message has been edited by ArthurPeale (edited 11-16-2022).]

quote Originally posted by Kitskaboodle: As an additional fyi, I had the small orifice egr tube gasket on the “wrong” end. (egr valve side) Even after correcting this, my Nox numbers were still about the same. (I took it to get smogged again because I thought this was the culprit but it failed again with pretty much the same Nox numbers. Kit

Kit, doesn't this suggest that your EGR system as a whole isn't working correctly? In your tests of components, the Solenoid works and the vacuum is sufficient to open the Valve. But given the same NOx results with the orifice in the two different locations, NOx is hardly effected. [I guess an alternative explanation is that the restrictive gasket gives the same exhaust flow regardless of which end it is sitting in.] This would mean the dire warnings about the intake side being the correct location are wrong.

If you check Rodneys site (egr section) and also the FieroStore, both will tell you that A) the small orifice gasket goes on the intake plenum side and the “normal” bigger hole egr tube gasket goes on the egr valve side. B) The reasoning for this is that IF you get a vacuum leak at the egr tube, the restriction will minimize the vacuum leak.
If you have the FieroStore egr tube, you can use the big hole gasket on both ends as the tube has a built in restriction already.
For the factory egr tubes (which have both ends the same hole size, this is when you need the restrictive gasket.
Kit

quote Originally posted by Kitskaboodle: If you check Rodneys site (egr section) and also the FieroStore, both will tell you that A) the small orifice gasket goes on the intake plenum side and the “normal” bigger hole egr tube gasket goes on the egr valve side. B) The reasoning for this is that IF you get a vacuum leak at the egr tube, the restriction will minimize the vacuum leak.

interesting. So, the only reason is a "just in case of breakage" issue. Cool!

regarding my previous question for possible cross-reference, any other gaskets that might fit?

Here's a head scratcher (for me anyway): the post-Thanksgiving, Christmas decoration time is here and the Fiero is in the way. So instead of pushing it out/in of the garage as I have been doing, and looking toward ease of movement during the holiday season, I put the EGR tube back on. I thought I'd try a little experiment and put a big OD gasket on both ends, figuring with the EGR closed at idle it wouldn't matter, and who knows, maybe the higher amount of recirculation at the higher test rpm might lower my NOx. Well, just starting the car it went to 4000+ rpm right away. I switched the car off and checked the TPS (yes, plugged in), and the throttle cable (yes, connected and responds to the gas pedal) but everything looks fine. I did this several times, never running for more than a short burst.

Now, BEFORE I go and replace the intake-side with the tiny-hole gasket, does anyone think there is another cause for this runaway rpm?

[This message has been edited by Notorio (edited 11-26-2022).]

quote Originally posted by PhatMax: I believe the EGR Gasket has two different gasket is because there is a “spacer” block between the ear and the exhaust pipe. I’m not sure why it makes a difference which end the smaller one with the restriction goes

The reason the small orifice gasket goes at the manifold end is to prevent wide open throttle in the event something happens to the EGR tube or valve. I have seen just one EGR valve that totally failed and the pintle and diaphragm were just floating freely and wide open. Should the tube break, you have an open source of fresh air and the sensors will try to balance the air/fuel mixture and it's off to the races.

Edit: Didn't see Kitskaboodle's post, but it's worth repeating because so many make the mistake.

[This message has been edited by fierofool (edited 11-26-2022).]