Failed Emissions Test

[grimsby3]

So living in Ontario, I'm forced to get an emissions test every year my license sticker expires and driving an mx-3, apparently a legitimate sticker is hard to come by especially for the v6's. Anyways, I took it to the shop today after spending about 200 bucks to get the muffler replaced with an OEM muffler and about 10 minutes later I have a sheet in my hand with that dreaded F-Word. If anyone knows anything about emissions testing, my results are:

HC ppm: limit = 68 my reading = 29 *(Pass)*
CO%: limit = 0.38 my reading = 0.04 *(Pass)*
NO ppm: limit = 526 my reading = 902 *(FAIL)*

This was for the ASM2525 test (the moving vehicle test) if anyone knows anything about the testing, could you explain to me what NO ppm is and what it means and how I can improve the numbers? The guy I went to said it was because of "high NOx" (nitrogen oxides) this being said, he's not 100% sure why the numbers are that way and wants to do a scan on the ecu to make sure the O2 sensors are working properly etc., he said there are about 4 O2 sensors on the mx3 but when I put the car in the air, I only see the one right on the header coming from the front of the engine. I assume there's another one on the other header though. His other suggestion was too much carbon in the engine, it was running super hot so the gases were burning at a higher temperature therefore causing high numbers, or a faulty catalytic. God I love Ontario's drive clean laws. pretty much a money grabber imo.

Any suggestions by anyone here? Or better yet, anyone know any one who can... look the other way shall we say for a fellow mx-3 driver and figure a way around the whole shenanigans that are my engine.
ps I don't want to spend hundreds of dollars on this thing because as much as I love her, shes already got about 321,XXXkm on her and I can't justify putting more money into it then I have
Thanks for any input

[_-Night-Shade-_]

There are 2 oxygen sensors on a GS. High NO usually happens when the combustion temperatures are too high. The EGR is implemented to help with this, but it's a PITA to replace... maybe start with oxygen sensors? You may just need a newer/fresher cat too.

[grimsby3]

I figured there was only 2, I'll check them out on my school's scanner on monday, see what/if anything they say. And what's the easiest way to keep combustion temperatures down, I drove the car for a good few hours before the test so it had to be hot as hell, maybe less driving before? I've always heard to make sure the engine is nice and hot beforehand. And I hope its not the catalytic, although I could probably grab one off a wrecked mx3 depending on the condition, thanks for the info
ps what does PITA mean? lol

[_-Night-Shade-_]

P.ain
I.n
T.he
A.ss

Hahah. Combustion temperature isn't the same as operating temperature. It's good to have the car all warmed up and stuff, yes. However, if the temperature inside the combustion chamber gets hot enough then the nitrogen in the atmosphere is allowed to combine with the oxygen and you get NO emissions (oxides of nitrogen). End of today's lesson lol.

[Daninski]

You could try removing the EGR and cleaning it. I'm wondering if a plugged cat will cause this. I'll find out tomorrow. Your spark plugs should be NGK 6's right. If yours is a 95 it only has two O2 sensors,the OBD2 has 4 but if the bottom two aren't there it doesn't matter. Check the vac hose is actually on your EGR.

[_-Night-Shade-_]

On both of my K8s the EGRs were pretty much seized in place, I figure the only way I could remove it would be with the rear header together That's why I say it's a PITA. Who knows, maybe yours is in better shape.

[Daninski]

Mazda uses pretty good hardware and I haven't had any problems removing bolts from the last 3 engine swaps I've done.

[_-Night-Shade-_]

Mazda uses pretty good hardware and I haven't had any problems removing bolts from the last 3 engine swaps I've done.

The bolts aren't what I had problems with, it was the pipe that goes from the rear exhaust primary to the EGR itself.

[grimsby3]

Thanks guys, I'm going to attempt at pulling my EGR off tomorrow and giving it a thorough cleaning. I tried today but only ended up getting the intake tube off and the throttle body and ended up cleaning all the crap out of the throttle body. Do you have any general tips on how to take the EGR off a K8? I think I located where the sensor is but have only an approximate idea where it is, I checked the vacuum lines going to it and there doesnt look to be any major issue there other than the fact they are like, warped onto the outlet because of how long they've been there for.
If you have any like, step by steps on how to take it off that would be much appreciated

[_-Night-Shade-_]

It will be easier with the Intake Manifold off. Also I know of successful attempts from under the car as well.

[grimsby3]

**Update** Long story short: 5 hours later, one broken bolt, egr still dirty

So I took it my friends' dad's shop today and started taking everything off ontop of the engine (battery, intake tube etc.,) and then realized, hey! this shits just easier to get at under the car. So I get under the car and get the 2 mounting bolts off fairly easily (besides the non-existance room to move a wrench or ratchet) and then realized that I have to take off the pipe going from the egr to the exhaust manifold, so I try twistin it off with a monkey wrench, not really realizing it would be a much better idea to secure the egr valve with the mounting bolts while i'm twisting the hell out of the egr pipe fitting
So we end up running out of time because the sun was going down and we were parked in front of a bay that needed to have a car put in so we start putting everything back together, only to realize in the whole process of getting that fitting bolt off, we warped the pipe that leads to the exhaust manifold so it doesn't sit flush with the block anymore. So we try putting the one mounting bolt back in and get it snug and then try and crank the other to make the valve flush with the block, ended up breaking the head of the bolt right off. So now my baby sits in a parking lot waiting for a set of torches due to arrive tomorrow morning so we can heat up that damn fitting and get it off so we can clean it and then go from there.

[ManduMX6]

I also failed emissions.. twice. Also due to NO ppm. Passed everything else with flying colours...

1st attempt (stock CAT):
NO ppm: Limit 0435 - 589 = Fail

2nd attempt (New CAT):
NO ppm: Limit 0435 - 2232 = MAJOR FAIL.

--

So, I am also doing the EGR cleaning a.s.a.p. I am going to attempt from the bottom. My o2 sensors are apparently fine. -shrugs-. Why it is worse the second time with the new cat is beyond me. The old one was in really bad shape, couldn't even see through it and it was very .. just.. dead. The new one is a universal, had it welded on.. much smaller than the stock cat but it does the job.. car actually sounds a little different.. i like, i like. Either way, It failed horribly the 2nd time.. Do you think it's the EGR causing the problem???

Not to jack the thread or anything

[_-Night-Shade-_]

Sounds like your new cat is an aftermarket one so it won't be as good as OEM. And it's smaller so there's less catalyst. Both of those mean that much less of the NO coming in will be converted. That's why it's higher the 2nd time. Also what O2 sensors are you using because they do play a role, even if it's a small one. If they're causing you to run lean that will also raise combustion temperatures.

Don't forget that high-flow cats are designed for performance, not emissions. I couldn't pass with my K8 but it was probably because of the magnaflow cat I have; the standards are just too high for the little amount of catalysts that are in them.

[Daninski]

The EGR is there to lower combustion temp to help reduce NO. I would of loosened the EGR pipe on the manifold and folded the EGR back then cleaned it. Jack the car remove the crossmember and that should give you good access. A guy who bought my MX-3 had the same issue wanted to by a new one. I told him to just clean it and he passed no problem. By the way take your car back and get your money back on that shitty cat they sold you. buy a good cat not some $70 buck one and one watch out for those high flow ones. They don't work too well with emissions tests.