Emission inspection problem.
 

Greetings, I'm having difficulty passing NC emission inspection on my '93 R1.

This is going to be fairly long, and I apologize for that in advance. I've searched over the past few weeks (after the first time it failed), and tried a few things. I first took the car in as it stood, Apexi intake, 3" DP, stock cat, 3" cat-back (those are the mods that really matter for this), running stock boost levels. I went in for the test, and the car had to sit for about 10 mins before he was able to get to it (Mazda dealer). Well, he pulls it in, and tests it........and it fails due to high HC's and CO. Passing HC's in NC is 220, and mine was 1453. Passing CO is 1.20, and mine were 5.84. The tech came to me and said the stock catalytic converter was punched, which is why the numbers were so high.

So I came home, and searched and found someone with a stock cat, and he basically gave it to me (which I greatly appreciate). He said he took it off his car in '99 after passing his emissions with no problem. Ok, cool I think. I do a bit more research and start looking at the air pump, which might be faulty. So, I find one on the board here, buy it and replace it. I also bolt up the new CAT. I replaced the apexi intake with the stock box, and went in for retesting. Well, now it failed even worse. HC's of 1944 and CO of 5.84. The car was immediately pulled into the bay and tested, so it was nice and warmed up. (So basically it was in stock trim except for the DP and cat-back).

I'm obviously running very rich. I don't have a PFC on there to lean things out with though (don't have the cash at the moment either). I do have an SAFC on my Eagle Talon, but if memory serves me correctly (it may not), the SAFC doesn't work well with the RX7? Would that help for a day to lean things out and get me past the inspection?

Also, while searching just a few minutes ago, I saw someone mention the water temp sensor, and that a bad one made him fail emissions. Would that make my car run THAT out of spec? I have a limited time to get this fixed before I'll have to pull it off the road (I just moved here and have XX ammount of days before it has to be passed). Anyway, any help would be greatly appreciated. I did search, but everything I've come across or thought of and tried, hasn't worked yet (except the water temp sensor). Thanks guys......you guys are always willing to help idiots like me through tight places, and I know I (and most others) think super highly of all of you.

PS--other mods in sig, but I don't think any of them apply to the emissions part of this.

Sounds like you might be burning oil too. Are you pre-mixing? This would bump those #s up. Also, try using a high alcohol content fuel and disabling your turbos in case your getting some oil blow into the intake.

Is your airpump working and connected properly??

Haven't noticed any burning oil at all, and I'm not pre-mixing.

As for the airpump, it's hooked up properly, and I just replaced it with another (used) unit, although I guess it's possible that that unit is bad. I'll check it today.

What about leaning it out with an SAFC to get me through inspection, anyone have any ideas about that?

come on. isn't there anyone in NC that can hook this guy up with an inspection? :D

zmarko - fwiw, there are some threads about tricks to pass inspection including use of denatured alcohol and such. try searching for them.

Worse case scenario if you really need it, I have a low mileage pre-cat in my attic that I can sell you.

Or you can try to weld in one of the new metal substrate cats into your downpipe. Some dude that moved to NV just did that and was able to pass inspection there.

I'm in the same boat, but in Atlanta.
Reading Allowed
HC 475 132
CO 3.34 0.73
NOx 127 945

I orginally thought, I could change the cat (newer one) and it would lower some levels...obviously not the case here.

The funny part is...I have a highly modded single turbo, and my numbers are way better than yours.

I bet your O2 sensor is shot...not the cat.

I've been reading about denatured alcohol. 1 gallon in a quarter tank of gas...should help.

^oh yeah. I don't think leaning out a map would help, as I'm running a 14.7 A:F while cruising, verified via wideband.

my 25mph and 15mph tests were almost identical...so it seems my 02 is working, correct?

OK. I guess the next step is to replace the O2 sensor, and then maybe the water temp switch. Is there any way to check if the water temp switch (which was stated in a different thread) is good or bad?

I see no way how a water temp switch would cause bad emission readings.

If you fans turn on at 210 with the park lights on your switch is working.

Wouldn't a bad O2 cause a CEL though? Cause there's no CEL on now.

Zmarko, if you try that and that fails for you, I might be able to find someone to "pass" you but it would most likely be in the Charlotte (surrounding area) area. Please PM me if interested. Good luck :)

Thanks dude, I could be wrong here, but don't you have to get inspected IN the county your car is registered? For some reason, i have that in my head, not sure why.

If not, I might take you up on that if I can't get this worked out.

Change the oil, spark plugs, spark plug wires, and O2 sensor. Add 1 gallon of denatured alcohol to 1/4 tank of gas. You might try wiring open your wastegate, as boost makes the car run very rich.

Just be glad you're not in IL or California. I'm doing a complete overhaul (vacuum, fuel, oiling, electrical) to try and get my car to pass IL's stupid dyno emissions test.

Also, make sure your car is really hot when you go in for testing. Take it for a half hour spin out on the freeway and get those temps up to make the cat perform at its best.

Good luck,
-Colin

no...only if its not connected will it throw a code.

There's something wrong with your car. I had a friend with a similar experience and it turned out to be the ACV! It wasn't properly switching to feed air to the cat, although his numbers were far better than yours.

Get your car fixed, it will run better in general, so it should be worth it.

If it turns out you need an AVC...I've got one I can let go. I'd imagine a dealer wants upper hundreds for it.

You've got a PM.

now we're getting somewhere :)

I was having problems passing IL's dyno.

Bad EGR (didn't show up as CEL)
Bad Air Intake Thermosensor(only showed up intermittently CEL)

fixed those, new plugs, oil, got it nice and hot, and went at an off time to minimize any wait, and it passed twice(but still barely each time).

Well NC's sniffer is just that, just a sniffer that's done at idle, so I'm not worried about it being in boost during the test.

So, possible culprits are:

Bad O2 sensor.
Bad ACV.
Bad EGR.
Bad Air Intake Thermosensor (my car has never thrown a CEL during my posession, so I don't think it's this).

How can I test these to see if they need replacement? Or do I just need to start replacing stuff and re-test it each time?

How old are your plugs and wires? If it's an idle test, spark plugs should make a huge difference. I would install 6's and 8's for an idle test; copper plugs, not platinum.


Also, what is your idle RPM? You might want to lower the idle to the minimum allowed. Less RPMs = less air & fuel ingested, correct?


I've heard that a few people have had good results from changing the wiring to the air pump: run it all the time, and you should be set. The air pump does not always kick in at idle.


California has some of the toughest emission tests around. The West section of the forums has a thread about passing smog: https://www.rx7club.com/showthread.php?t=247935

-s-