neuro

I failed Colorado's smog check because of no front catalytic converter. Does any body have an old pre cat for a 93 FD

Montego

iTrader: (1)

I take it you failed visual and not functional? If so I would try taking it to someone else first. But if you are dead set on it: PM Fritz (he is the go to person) and see if he has one. Just make sure you gut it out prior to install.

adam c

iTrader: (2)

If you continue to post garbage like this, just to increase your post count, you will quickly make enemies on this forum.

zli944

iTrader: (2)

hey adam, on an unrelated note, how do you go about passing smog in CA? I noticed from your title you're also located in CA. My car passed smog with the stock cat, ECU and downpipe.

But undergoing reliability mods, I've replaced all three w/ aftermarket. HKS DP, RB catback and PowerFC.

I have the stock downpipe, stock cat and the stock ECU, and I have the 4 wires for the PowerFC hooked up w/ connectors so I can reattach them if necessary to put the stock ECU back on. All other emissions things (Air pump, EGR) were retained.

The main cat and ECU I am more than willing to swap out every two years to pass smog but the downpipe... it was a pain the first time swapping it out and I can't imagine it getting any easier...

I figure I could probably pass visual no problem... but with the HKS downpipe, stock cat and stock ECU could I pass the sniffer?
Or is there a way I can setup a "smog" tune with the PowerFC?

Montego

iTrader: (1)

wstrohm

It may indeed be a "trap," but I'll throw in my $.02 anyway:
I would say yes, from my experience. I have a Bonez downpipe replacing the pre-cat, blocked EGR, stock ECU and stock cat. A late test is attached here. (Note the mileage on this car, with its original engine.)

adam c

iTrader: (2)

Most smog techs wont notice the downpipe, so if your car runs clean, it should pass.

jza80

iTrader: (32)

My 1995 R2 is a "test only station" car, probably all CA-titled FD's are the same due to the emissions profile of the FD3S. Where I live, it is the ASM loaded dyno test and using just a stock ECM and stock main cat it passes (very low CO and HC, NOx is about in the middle of the allowable range but fairly big numbers.

My car has a JDM Mazda downpipe, it has the OEM heat shielding so it looks a lot more like the catted DP then an aftermarket one. Still, at my last renewal I needed a smog inspection and the tech looked at it with a flashlight for quite a while - actually they looked the whole emissions system over fairly extensively. Only mods are the DP, and a Blitz SMIC that I had covered up with "heat shielding" for the inspection.

I think if I had an aftermarket DP, I would have failed visual at this shop. But, every situation is different for sure.

To the OP's main question, some regions have the ASM test and some are a idle and 2500 RPM unloaded sniffer test depending on the degree of air quality nonattainment for the county. If you are in an ASM region, the Power FC may not cut it for emissions control, and you will also need to modify the check engine light circuit so that it displays briefly at key on like the OEM ECM to avoid failing visual inspection. If you are in a non-ASM region then the Power FC with good tuning and a good main cat + the check engine light mod should pass tailpipe emissions. But the DP is still an open question.

...I wish I had a way to register the car out of state and avoid this whole nonsense - and the upcoming increase in registration fees - but for now that is more hassle than it is worth.

wstrohm

Agreed. Our '94 has been a "Test Only" car since new, for the reason you mentioned (it shows on the reports). But the DP area is very hard to spot unless the car has mods that expose it, and I have never had a problem with the visual inspection from a tech.

Also, I have found that the stock cat (which I had to replace once) is the critical item in sniffer performance... the Bonez cat I once bought failed smog testing when new, but the replacement stock cat worked (and works) as it should. I think it has something to do with its internal construction, i.e. maybe the injected air distribution inside the cat is better designed than on aftermarket parts. But it is expensive!

wazway

iTrader: (9)

I have a stock JDM catless precat, looks just like stock with no restriction. PM me if you are interested

jza80

iTrader: (32)

The amount of precious metal and transport area in the OEM cat are vastly higher than any aftermarket cat. That thing weighs a ton! I have actually picked up a sub-10K mile OEM cat that I am keeping in reserve just for smog check in case the already low mile OEM cat now on my car degrades and/or CARB again lowers the pass limit levels and I need more emissions reduction. CARB has been talking recently about doing this...

jza80

iTrader: (32)

The JDM DP's are smaller in diameter than aftermarket ones, but if you are running an OEM cat the piping reduces down to the same measurement anyway so there is no negative impact I think. And, the JDM DP has excellent OEM heat shielding which must help with underhood temps

It's not the same as a catted DP in appearance though, as I mentioned.

arghx

iTrader: (3)

In terms of measured emissions at the tailpipe, as long as the stock main cat isn't degraded past useful life and the ACV/airpump is working you should be fine for any emissions test that doesn't require the vehicle to sit overnight and cold start. The precat is for the cold starts in the EPA procedure, because it heats up faster due to being closer to the engine.

Yup. That's why OEM's try to design an engine that has low engine-out emissions, so they don't have to put an expensive cat on there. And the precious metal costs vary over time, so it's hard to predict how much they're going to be.

You should have O2 feedback on (of course it is on stock ECU, but turn it on if you have a PFC). Replace your O2 sensor. They tend to bias rich (higher CO%) or lean (higher NOx) very slightly even when new, but especially as they age. Newer cars compensate for this, but not pre OBD II and no aftermarket ECU can do this.

You can tell if your O2 sensor is biasing rich or lean by looking at the CO% and NOx PPM for a condition. So here is the most recent California emissions test for my car from the previous owner, 49k mileage on a basically stock vehicle with stock ECU:



Notice how NOx is above average (average of passing vehicles), while HC and CO are below? Also notice the 2.4% O2. That's definitely leaner than Lambda=1.0 . High O2% is associated with lean running and in some cases poor mixing in the combustion chamber.

I don't live in an area with tailpipe tests so I replaced the USDM pre cat with the JDM downpipe and elected to keep the biased O2 sensor, because running leaner in closed loop is better for fuel economy. I'm very happy with the JDM downpipe due to the heat shielding and quiet sound.

zli944

iTrader: (2)

Thanks man.

Not sure how this is a "trap"... but just wanted to get a feel for how other CA FD drivers were passing smog.
Saw a nice MB at Rick's Rotary that'd been there for weeks trying to pass smog