Hi
I live in Norway and imported my 1993 Mazda RX-7 from USA in december 2006. In january 2007 the car caught on fire because of a small gasoline leak and an extremely hot, clogged pre-cat. After my insurance company paid about $20.000 in repairs and the workshop cleaned out my pre-cat, effectively making it nothing more than a downpipe, I'm having troubles passing the emissions test.

Do you guys have any tips about reducing emissions without having to replace the pre-cat? .. I don't really want one in my car as the same thing could happen again (it getting clogged). Is it possible that my main cat has been damaged as well because of the pre-cat being clogged?

I've bought a new downpipe and a high-flow main cat that I'm going to install soon, but do you think that'll be enough to clear emissions?

If all else fails, I guess I'll have to get a pre-cat to install just for the emissions test and then get it out afterwards. And in that case, do any of you guys know of webshops in the USA that ship these internationally?

Any help is greatly appreciated. I've barely driven my car 2000 miles since I bought it, and that's a bleedin' shame!

 

You should be able to pass without it no problem.
There could be a problem with the main cat, how many miles are on the cat? Any more than about 50,000 and I would be looking at a replacement.

 

Thanks for a quick response!

I think the original cat is still on, and seeing as my car has over 70.000 miles on it I guess you might be right about it needing to be changed. Seems that buying that high-flow cat was the right thing to do then

 

You should also ensure that the air pump and Air Control Valve are working per the FSM,otherwise you will have trouble passing(depends on how strict the test is)

 

The pre-cat breaking down can send debris into the main cat, thereby, clogging and destroying it. I have a downpipe, hi-flow cat, and cat-back and it passes emissions in the States. If they check visually, they'll fail you if you don't have a pre-cat (since it's listed). You'll just have to go to a tester that's not as thorough. But as far as passing emissions, my set-up has been fine. I did have trouble one time, and my tech told me to get the hi-flow cat very hot (drive it hard) before you go in for the test. Good luck!!!

 

I just passed about a month ago with a 3" downpipe. Just make sure the cat you DO have is still good.

 

Okay...I spoke too soon. After getting my car working again after sitting pretty for about a year, it failed emissions today. A new O2 and water temp sensor was put in recently, which tells the Pettit ECU what to do about the air/fuel etc, and the cars been running like a champ.....probably the best it's ever run since I've owned it. But of course SOMETHING had to give. It IS my rexxer!

So lo and behold, the HC ppm and CO levels were almost 3 times the limit. It failed once before....my tech told me to get the cat really hot....and then it should pass...in which it did. Nothing else done. I'm hoping that'll work again. But I'm a bit skeptical this time.

I'm hoping it was the year old gas in the car, or the cat that hasn't seen much exhaust in the last year (only 130 miles since the fix), or the ecu taking its time figuring out the new calculations with the new inputs. (Before the fix, the car was stalling and hesitating.)

I did see something at Advance Auto that you can put in the gas and it's guaranteed to pass emissions or something.......

Thoughts anyone?

 

All I can say is that I bought a "Random Technology" highflow cat for my car, and I passed smog ( with a working air pump and the car had to be in second gear during the 25mph test). Honestly, all I did to pass smog, was get my Air Pump working properly, and replace the main cat. My precat does not work, and is only on for the ride, but the main cat allows it to pass smog.

 

Mazda ran the Pre-CAT for the series-6 version from 92-95 as the 8-bit control ECU required a little external help.

The series-7 (96-98) & series-8 (99-02) versions both had a 16-bit ECU for control.

If your series-6 version is over the limits, then try updating the ECU to a modern aftermarket version that controls the twin turbo's. Haltech, Motec, Apexi all do this & I think the Motec is a 32-bit system that makes accurate fuel metering possible thus better controling your emissions & making plenty more power to-boot.

REgards

 

I am tell you guys 1 thing... If the smog tech actually know his stuff... You WILL NOT, I can guarantee you that, WILL NOT pass smog under visual inspection. And it will be failed under MODIFIED. I know because I am a smog tech... if they are nice, they can let you go. But here in the state (California), not as easy as you thought. Because BAR is cracking all those bastards who's doing bad smog.

 

You would fail the visual, but if you drive the car around to warm up for approximately 20 minutes, it will heat up the main cat enough to get it to proper operating temperature. Also good to keep the car running from that time until it's hooked up for the emissions test. If you haven't done so also good to change the plugs and the oil.

 

Good idea. Also, put in a tank of premium gasoline (if you usually dont fill her up with premium) and add a bottle of rubbing alcohol in her. She will run pretty clean.

-AzEKnightz

 

The OP is in Norway so what you said probably does not apply at all.

I refereed a '95 13b-rew into an FC, successfully in CA. I couldn't get the original precat to fit, so I used an ebay down pipe with a hollowed out universal CA certified bullet cat welded in and a universal catco in about the same place as the stock maincat.

Since the car is pre OBDII this was perfectly legal (no vehicle specific CARB certification required for the cat). They did question be about it (actually wanted to see the receipt, because the stamped number was really hard to see without removing the pipe) and also cracked open their manuals and finally called their supervisor about that particular aspect. They did way more than the normal smog test on the car which really seemed as if they where trying to make it fail.

Anyways, the totally CA VISUAL legal way to go about a down pipe, is to put a hollowed out CA legal bullet cat in it thats CARB certified for use in cars that match the year range and engine size. The car won't fail visual for this reason, and if it does a ref will pass it.

 

first of all, I think you've mistaken what my point was. I knew that he was from Norway, that's why I said it would FAIL if it was in CA.

Second, what you stated is, because you cant get the original precat to fit. BUT, you did put in a cat and its a "certified bullet cat". You've missed the point that, the cat, has been totally replaced by a downpipe. So nothing is infront of the Main Cat. I had my car pre-smog at smog school. And I am 100% sure, that in the book, it stated that "2" cats are required (A Pre-cat and the Main Cat). Most people or smog techs that doesnt know about this... Will simply pass it without checking if there are 2 cats or not.

Another thing is, when you drop a 13B-REW into an FC. They will NOT consider or smog that car as an FC. They actually smog the car as of an FD. But on the documentations, it will be still listed as an FC.

Maybe that's why the tech who was smogging your car was so strict about that cat you have in there.

Hopefully this clarifies my point.

-AzEKnightz

 

I would add one more point: in my experience it also matters _how_ the tech runs the test.

I have the same setup as deish describes, no precat, and where I live the emissions test is done on the dyno.

My car failed (even with a brand new cat) until the tech got it to pass by running the test at the upper limits of the specified RPMs to drive the air pump at peak efficiency. Lower RPMs == too little air to the cat.

I was pleased to get it through without having to resort to alcohol; that was going to be my next move.

 

Your right! the same thing happened to me when I tried to pass smog. The first test at 15mph I passed but the second test at 25mph I failed barley, but when I told them to increase the RPM's being that it was WAAY too low ( a little bit of arguing involved), they finally did, and I passed almost with flying colors with just a working air pump and 1 working cat. Also more importantly , it runs super clean now, no more race fuel smell!

 

put a bottle of cataclean in the fuel tank,15ltr of fuel to one bottle,then it will pass.

 

If you could find a smaller pulley to put on the air pump it would effectively overdrive the air pump making it work more and have the exhaust "cleaner" at lower rpms and higher.