Failing Emissions caused by EGR blockage

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YoYoTercel
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My tercel:: 1983 Tercel 4x4 SR5

Failing Emissions caused by EGR blockage

Post by YoYoTercel » Thu Mar 09, 2017 3:17 pm

After an extensive tuneup and replacement of the Catalytic Converter (with muffler) - on my newly purchased Tercel, I failed emissions :x . So, I decided to open up my EGR valve. It was completely blocked....that's why my Nitrogen Oxide levels were too high. Also, I believe that this will eventually lead to a head gasket failure - due to he backflow of heat generated. I tested the EGR vacuum before the test (it was holding vacuum) but I should have removed the whole EGR to clean it out before I embarked on my emissions test. So folks, check your EGR valve passages.
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: Failing Emissions caused by EGR blockage

Post by Petros » Thu Mar 09, 2017 8:28 pm

"back flow of heat generated"? the EGR lowers combustion temperatures under certain driving conditions by cycling in exhaust (which displaces O2, and dilutes the mixture). when peak temperatures and pressures are limited by the EGR, it lowers NOx which form at those peak pressures. it lowers efficiency and lowers fuel economy, and peak power output.

If you are getting ping and preignision with the EGR disabled, it could eventually cause head gasket failure (it also reduces efficiency), but adjusting the timing and going to a higher octane gasoline would solve that without the loss in efficiency. I have noticed that despite the higher fuel cost, the higher grade of fuel actually results in better fuel economy off setting the higher cost, so cost per mile is better than with regular grade fuel. My EGR has be carbon plugged for many years, and choose to leave it this way since I do not want to sacrifice power and efficiency. We do not have emissions testing in our state for cars over 25 years old, so it is not an issue for us.

If you are in a state that requires to pass emissions testing, than you have no choice but to keep it operational. Otherwise it is not really helpful for a good performing and efficient engine. No cars had EGR systems on it until about 1974 or, and some cars did not need them until about 1990 or so. they were clean enough to not need them. It can run fine without an EGR, but you have to make adjustments for the higher temps in combustion.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
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YoYoTercel
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My tercel:: 1983 Tercel 4x4 SR5

Re: Failing Emissions caused by EGR blockage

Post by YoYoTercel » Thu Mar 09, 2017 9:22 pm

Yes, I'm in California, so I have to make this EGR work for me. Thanks for the update. Hopefully, when all is cleaned and put back into place, I'll pass with flying colors.

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Petros
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Re: Failing Emissions caused by EGR blockage

Post by Petros » Fri Mar 10, 2017 12:42 am

there is this gasoline additive that supposed to help you pass, it has a rather dubious name called "Guaranteed to Pass" or something similar. Not sure if it works or not, but might be worth a try. If it is an octane booster it actually might help.

Also, make sure you back the ignision timing to the factory 5 deg BTD for the test. than put it back to 10 deg after the test.

good luck
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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ARCHINSTL
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Re: Failing Emissions caused by EGR blockage

Post by ARCHINSTL » Fri Mar 10, 2017 3:53 am

This is what I did back in late 2005 to get Goldie to pass - which she finally did (no longer required in MO):
viewtopic.php?f=7&t=1496&hilit=egr
Mine was blocked solidly, while yours apparently still has a tiny passage.
Tom M.
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YoYoTercel
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Re: Failing Emissions caused by EGR blockage

Post by YoYoTercel » Fri Mar 10, 2017 9:14 am

Thanks Petros and Archinstl for the great information. I just sprayed Carb and Choke cleaner into the blocked areas, let it soak and slowly picked away at the "soot". Eventually, I got everything cleaned up and put back. I made sure I used anti-seize on my bolt threads because I could feel how the bolts came out - DRY and creaky.

If I don't pass, I'll try some of the potion you recommended Petros.

xirdneh
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Re: Failing Emissions caused by EGR blockage

Post by xirdneh » Fri Mar 10, 2017 9:43 pm

cleaning those things is a PITA
the last one i did i drilled 3/16 dia holes in hard to get at spots and after cleaning tapped the holes and plugged them with 1/4-20 screws that i cut down to about 1/8 inch of threads.
Love those Tercell 4x4 wagons but they sure suffer from road noise.

YoYoTercel
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Re: Failing Emissions caused by EGR blockage

Post by YoYoTercel » Sat Mar 11, 2017 12:05 am

Yes it was a PITA to clean. All hard and crusted. I actually thought about it carefully when I had the whole thing apart. I ended up putting a new egr valve, new oxygen sensor and putting the whole thing back into the car. The result was that I passed emissions with very low numbers. Here's what I leant. The muffler shop told me that my catalytic converter was all plugged up. It resulted in some kind of back pressure restriction. In addition, my old egr was plugged up completely - resulting in failure at the emissions. Also, my oxygen sensor was all coated with gunk. When I changed all that, my car actually ran smoother with more power. The temperature guage was also consistently at the middle mark. But the main thing is that I am now confident that my car will pass California Smog for many more years to come.

letankT
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Re: Failing Emissions caused by EGR blockage

Post by letankT » Thu Mar 12, 2020 10:49 am

BTT, I did the same a few days ago. But I cleaned up the passages and the intake manifold opening, w a small pick then a drill bit to clear the carbon crust. Same for the EGR with the pick and a bit of pb blaster to soften the carbon. Passed smog with flying colors. I missed the timing as the hood sticker was missing, I dialed wrongly, as I did not know that you have to disconnect the distributor vacuum line, so I was at -3, so I had to go for a retest to pass the timing. In fact there were discrepancy from one station to the other one said 5°, the other 3°, this is for a standard 3E engine.
Thank you for letting me join. All that was to help one of my former retired co-worker. Cheers to the list. I will post some pict later

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