Latch

My first car was a GSL-SE, back in 2000. I sold it to a friend who rarely drove it, and am considering buying it back from him. I took it in for a pre-test today and it failed CO and HC about four times over. This is probably the cat, right? Most threads say so, but other folks seem to fail on all three instead of just the two.

Here's my results.

AcidAngel7477

iTrader: (16)

hmm..if you arent too far away i could help that little problem..heh heh heh
and yeah its the cat..just replace all three..with one new one..but make sure that it has the little pipe for the air pump..it also could be your acv..might be going bad, so there you go the two top problems that cause you to fail..try those things and see where it gets you..
good luck..

:AA:

steve84GS TII

Dont be too quick to replace the cats.
Your CO is very high and your NoX is low,indicating a rich mixture.The HC is also high,but Ive seen proper running rotaries with bad cats that had HC levels in the thousands!!! Your HC numbers arent THAT high,indicating the cat might still be working.My EFI 13B numbers tend to be about 50PPM of HC because the CO is only around .05 or so....CO is a direct indicator of mixture,so is the NoX levels.My NoX is usually a little higher because I have a S5 with higher comp ratio and no EGR.
The cats could be good,but they cannot overcome all the pollution caused by a bad ignition system,improper timing or faulty EFI parts.Id make sure to do a full tune up first and check the timing.Also,be sure the AFM flapper door is working smoothly and Id most definatley pull the injectors out and have them cleaned and tested.Its also possible to pull error codes from the ECU to determine any electronic EFI problems.its not as simple as reading the check engine light,unfortunately,so if you cant figure out how to do it,then have a dealer,mechanic or SE guru do it for you.You might find something simple is wrong.

And make ABSOLUTELY sure that the engine,coolant and exhaust system are HOT before taking any smog test.That means running the car well before the test,like for 20 minutes to a half hour, and not turning it off while you wait to be tested.Keep it hot and your numbers could fall drastically.

All that stuff might add up to more personal labor than just replacing cats,but it wont cost much $$, and its stuff you should do to any used car you buy,especially one this old.And you might just find that after a simple tune up and freshening,the car can still pass smog with the old cats.If your gonna throw money and parts at it,might as well start with cheap ones that are regular maintenence items anyways.....

Latch

I really didn't want to hear this, but I'm glad you told me. I'm just way too busy to put much love into this car right now, but I don't want to send it to the scrapyard. It's pushing 155k miles and isn't exactly cherry, but would be a great daily driver for me. I'll just take it in to my local rotorhead and prey it doesn't cost a fortune.

Dougster

Good advice Steve,
yes, I would make sure its got a fresh tuneup first & check the timing...
Good luck/skill!

84RX7'nSTi

I was surprised when my '85 SE passed with just two cats functioning a couple weeks ago. The first cat had fallen apart and clogged the second cat, so I gutted the first cat and took the debris out of the second. The car ran great after my ghetto fix.

Mike

steve84GS TII

Yea,the small precats have less of a job to do.Depending on running conditions and ACV output,the precats can be in charge of various duties,it all depends on where the oxygen is sent.Smog tests tend to not have much decel coasting or heavy loads,so often you can pass easily with just a good main cat.

And running a modern 3-way cat can often make a big difference.The older cats are getting pretty cruddy and were made to handle smog standards that are way past passed up.They just recently started checking for NoX,before that you could have been NoX-ing it up like a wildman and it wouldnt have resulted in a test failure.NoX scrubbing is one of the duties that is passed back and forth from the cats,based on ACV function and engine conditions.Getting a good,effecient 3 way cat can make all that job juggling the ACV hands out,uneeded and moot,since the big main cat will be doing more work on its own.

Latch.....if you want to spend the money and just pop a cat on to try another test,then go for it.But they can be 200+ bucks installed and you likely will get an el-cheapo that isnt specifically made to hold up behind a rotaries hot exhaust.It might get you regged,but it also might only last for one smog test (2 years)
If you do decide to cat it up,then at least do a prelim. inspection of the state of tune.Check the cap and rotor,clean the plugs,check the filters and timing. And if you wanna splurge on a good rotary catylist,then check out the Bonez cats from RX7.com
They are not too much more money and you can often install them yourself with basic hand tools.Saves you labor costs and they hold up to anything a rotary can dish out......