Long story short while I was at work a couple miata enthusiasts checked out my 99, popped the hood, and found out it has no EGR. They were very excited when they were told that my miata was from Hawaii and that it passed smog without issue and said not having an EGR is a really great and valuable thing.
I'm trying to figure out why that's such a great thing as I'm clueless. Fingers crossed someone here can teach me a few things about that!
EGR reduces NOx emissions by mixing exhaust gases with the fresh air entering the engine. That lowers the oxygen content and slows down the combustion process and resulting temperatures. Air is about 78% elemental nitrogen (N2). N2 in the air is converted to NOx when the combustion temperature is over 1800f. It does reduce power a little, compared to the same engine without it. If it came that way from the factory it would be tuned for it. If you're removing EGR from an engine, it may run a little lean and you may need to turn up the fuel pressure a bit or have it tuned for no EGR. I wasn't aware that emissions regulations for Hawaii were different from the other 48 (not including California).
EGR is typically only active at cruise, which means that it doesn't cost you power at WOT. When active (such as at cruise), it gives you lower power for a given throttle opening amount. This is actually beneficial to fuel economy, because it reduces pumping losses.
IIRC, a lot of the Japanese market cars don't have EGR. I wouldn't be surprised if a Japanese-market car wound up in Hawaii through a military owner or something.
EGR does tend to crud up the intake manifold with carbon.
Have heard of people in Ontario who have bought used Japanese Market engines and been caught out by this lack of egr when it came time to do the emissions test. Seems that it is not simple to add it after the fact?
codrus said:EGR is typically only active at cruise, which means that it doesn't cost you power at WOT. When active (such as at cruise), it gives you lower power for a given throttle opening amount. This is actually beneficial to fuel economy, because it reduces pumping losses.
IIRC, a lot of the Japanese market cars don't have EGR. I wouldn't be surprised if a Japanese-market car wound up in Hawaii through a military owner or something.
EGR does tend to crud up the intake manifold with carbon.
This is exactly what I was going to type. And the last line is an acute problem for the BP in the '99-00 Miata, as other cars are more robust.
The one thing I will add, although it has little bearing on this thread- the fuel economy benefit is why you will see EGR make a pretty wide spread comeback. The emissions are pretty well understood, and are easily dealt with.
NOHOME said:Have heard of people in Ontario who have bought used Japanese Market engines and been caught out by this lack of egr when it came time to do the emissions test. Seems that it is not simple to add it after the fact?
Swap over the intake and exhaust manifolds from the original engine. Problem solved.
If it's a Japanese model, it should be RHD. I think the European cars were running EGR in 1999 - heck, there's a 1.6 variant in Europe with EGR, which never happened in North America. If the car isn't RHD, I'd check to make sure it's running a stock ECU.
Also, service members have to follow the same import rules as everyone else. So any jdm nb miata would be too new to import.
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