Passing Smog in an FD
 

Despite its poor emissions reputation, I think it is becoming clear from a variety of posts that I have seen over the past few years that a properly running FD will have no trouble passing. Quite a few people fail, obviously, but in general it seems to be due to some non functioning component (e.g., old O2 sensor, clogged cat, leaky injectors, non functioning air pump).

Here, for example, are my results from a recent CA emissions test. Car has 55k miles on original engine. All stock (for the test in any case) except for downpipe and RB exhaust. Used stock cat with unknown mileage.

Test________CO2%__O2%______HC(PPM)________CO%_____ ____NO(PPM)_____
______RPM_MEAS_MEAS_MAX_AVE_MEAS_MAX__AVE__MEAS_MA X_AVE__MEAS
15mph_1819_13.30__1.72_|_61__27__23___|_0.36__0.09 __0.02_|_493__157__106
25mph_2924_13.36__1.68_|_37__18__16___|_0.35__0.09 __0.04_|_516__161__104

Pretty clean. Be interested to see other people's numbers.

The slightly worrying thing is that the maximum allowable numbers have been dropping gradually for the past few years. I assumed that these were set at the time of a car's release.

Passed Dallas smog after a little work done at RP. Little things can make you fail, but it's a matter of finding them that's the pain.

moconnor, were you running EGR for your test?

Yup. The NO numbers can be a problem with a disabled EGR.

RiceFx306, what specific things caused you to fail?

I don't know my tags were from like '08. Just took it to the shop to get a choppy idle and misc things worked out after putting it back together after a few years. I planned to just do a shady inspection somewhere, but while it was in the shop they just took care of that for me and figured out little things like passages turning into orifices and minute little things. Expertise that I would've never figured out. :icon_tup:

Ive never had to smog my car but that's good to hear they pass fairly easy if everything is working. Really cool that the pre cat isnt needed to pass as long as you get past the visual.

Hmmm, my engine is from a 95, car is a 93, wonder if it'll pass since 95s don't have EGR. Precat is on though.

From what I have read, an EGR is not all that effective on a rotary (and the orifice on the '93 and '95 cars in tiny) so you should be ok for the sniffer part of the test.

However, depending on how energetic the smog tech is, you may have a problem with the visual inspection.

My smog tech spent 5 minutes looking for mine before he called me over (the emissions diagram under the hood is very misleading wrt its location) and verified its presence with a mirror. Techs in previous years have simply not bothered to look for it.

Yea I hear its a hit or miss with smog techs.

You might want to zip tie an EGR in there for the test.

For the record, my car was from out of state with no EGR.

The intake and intercooler were returned back to stock, as was the original Catalytic converter. It did have a Downpipe and a PFS cat-back exhaust, however.

I had a hell of a time smogging an old Previa van in the past, but I learned from that experience. I added in one bottle of HEET (methyl alchohol) for good measure: Third Time’s the Charm | Grand Mighty

and just went for it. The main cat did its job and the car passed without issue, except that the NOx readings were a bit up there. I can't say how much of an impact the alcohol made, but this is proof that you can in fact pass California smog with no EGR and no pre-cat, provided everything else is working as they should.

Fortunately, the pre-cat has very little to do with the snif test. Apparently, it was included by Mazda to heat up quick and start knocking down the emissions sooner with warmup.

Good job on passing! A stock computer is also key...

When I had my FC a long time ago, I used methyl alcohol to pass smog after failing twice. Didn't have the money back in high school to replace the cat.

I never thought of ziptying the egr there for visual. Isn't there a way smog techs can test egr?

I haven't had any problems passing CA smog, and I replaced the pre-cat with a DP. Otherwise the engine is stock and is well maintained. I do take it for a good warmup before I take it in for smog though.

The EGR valve is not needed on a rotary (plenty of "EGR" already there); see our FD's results this year with mods in signature below.

If they can reach it, yes. Really hard to without removing the y-pipe.