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So I CA smogged my salvaged 120,000 AT 95' MX-3 and the result was the following


_____MAX AVE Measured (Parts Per Million)
15M/hr 92_ 21_ 95
25M/hr 57_ 13_ 75

So I shelled out around 450$ on a complete tune up, oil change and put in GUARANTEED TO PASS to clean the injection and the results was:

_____MAX AVE Measured (Parts Per Million)
15M/hr 92_ 21_ 116
25M/hr 57_ 13_ 92


The only thing it helped with was NO and CO with an approx 35% reduction in both.


So What I hear when the car is warmed up is rough Idle, When I had a tune up they did a compression and came up with 110 121 150 170 not sure in what order. Around 3000 RPM I hear a rattling from underneath the car sounds like a bunch of rocks are bouncing up and down (the CAT)

I wanted to get the CAT replaced the one underneath the car for 215 (140 part +labor) and when he wants to order he says Mazda told him that the other CAT is one that fails first which is right in front of the engine. That one starts at 350$ and has labor cost of 100+.

RIght now I just want to pass smog and keep the car for another yr MAX 2. It's salvaged and I don't have much money to spend on it.

I'm not a car buff as much as you guys are, so I'm trying to learn sense of all the reading I've done on this forum.

I've been thinking about replacing the O2 sensor, I read one forum that said I can find an O2 sensor for about 19$. When I went to Kragen's Auto Parts they quoted the MX-3 O2 sensor for 100$ w/ lifetime of 100,000 miles

Here are some other things I think will be useful to do hopefully I'll learn to do it and not mess up too much...

Clean the intake manifold
Check/Clean the PCR and EGR
Clean Air Filter...
I already pu another Guaranteed TO PASS and will fill up afterwards with Premium + 10% Ethnol

I'm still wondering which CAT if any I should replace... the Universal one under neath ($200) or the one in front of the engine ($400)?


Any Help/instructions doing this would be appreciated.. I just need to PASS Smog and keep the car for 1 or 2 yrs MAX.

Regards,

Borhan

Just took out the heated o2 sensor.... any idea how to clean it?

Ok so I changed the Universal Cat to a generic one and I'm pissed cause I failed again.

It only helped my NO and CO which were passing before now my HC is still


_____MAX AVE Measured (Parts Per Million)
15M/hr 92_ 21_ 92
25M/hr 57_ 13_ 110

Any ideas?

your compression numbers are low...except for the 170. could be burnt valves and/or piston rings causing an excessive amount of oil to be burnt in the compression chamber...these kind of repairs can get pricey.

Thanks for your reply
That for sure is one of the problems, but I should still be able to pass...


The question I have now is

"Could it be that my new CAT does not react VOC's (hydrocarbons) and only reacts CO's and NO's since it was a cheap generic cat 'Walker Economy'?"

because my CO was reduced by 50% and my NO was reduced by 90%, but the HC stayed where it was....

IF the answer is that all Cats do VOC's (hydrocarbons) then it could be my stock O2 sensor not letting enough oxygen get out to react w/ VOC's...


Your thoughts guys...

Thanks

Borhan

GOD!! I'm glad we dont have those tests here in Nova Scotia..cause my car would definitly FAIL lol I gutted BOTH of my CATS cause they were chunked up solid from running too rich!

but my car is due for safety and they said that I needed to put a baffle in my (Soup can) cause he sould stick a handle in it.lol

good luck with the emissions test..

Yeah, E-Checks suck. I'm glad I just passed my last one because after December 31 Ohio is getting rid of E-Check

my car does the same thing to me at 3000 RPMs, i get a strange rattling noise underneath the car, and it also does it at a bunch of other random times....also when i take a left turn, even if its just a curve over 10-20 mph, it makes the same type noise near the front of the car, also if i hit a bump in the road or something...does this sound like the same problem you had? and if so what'd you do to fix it

Sure sounds like it... There is one way to check for sure... When your car is cold in the morning try to put it on a jack or just a 6 inch ramp to get you some room to go under neath the front of the car... when you're under there (be careful that the cat is not hot) give a few knocks to the 2nd cat ( the block before your muffler) I just punched mine a few times and I could hear the same familiar rattles which is exactly what broken pieces of bricks sound like when they're in a metal container.


Solution:
partsamerica.com or JCwhitney ... I found the cheapest on parts america bc my mx-3 is salvaged 52$ shipping included and had a muffler shop put it in for $40 you could have someone do it for less too. Solved the rattling and check out my new smog readings....

CO from
.36% to .05% 15mph
.36% to .08% 25mph


NO from
356PPM to 37 15mph
304PPM to 33 25mph

I was passing these before but failing HC, something else I realized in the process was that GUARANTEED TO PASS did not decrease my HC... it only reduced my NO and CO readings by 30% and did not change HC (or made it higher) I was looking at my dates the wrong way for my first post.

The only only thing that makes emissions go bad is that all the gases created by fuel because is the only thing that has chemicals the rest of the parts are just mechanical electrical components to make the engine run, no fuel means perfect emissions.

So lets bring the logic into the equation. What is harder to burn, low octane fuel or high octane?

Obviously high octane which means that putting in higher octane will make emissions fail do to the fact that unburned fuel messes O2 readings and make it hot pass the cat. Thats why people say that whenever running high boost or higher compression to use high octane, to prevent pre ignition, to lower the temperature in the piston chambers and have at the end a rich mixture and as anybody knows cats work better when hot.

So to start off,

use the cheapest lowest octane fuel and if possible go with almost an empty tank and drive the car very hard a few times to heat up the cat very good or go when it is a very hot day to help in every possible way.

Also, use heat grade spark plugs to have a nice hot glow to make those gases very very good.

You know how I passed mine. I created a switch that I could control manually when the fan turns on or off and I would disconnect the thermo switch very concealed. When taking it to the shop and the tech started the tech I would be beside the car and let it heat to almost 3/4 the temperature and when it would reach almost completely hot just switch it on real quick and this would make me pass emissions. I did the smog test by having the fan on all thew time and the car DID NOT pass emissions.

so, low grade fuel, high heat spark plugs, and if you can install an oil catch can between the PCV and the manifold and sneak in a cheap fuel filter on that same line to grab any small oil particles. This will guarrantee to pass emissions.

Because I have done the smog test by removing the PCV and let the gases from the cylinder go to the atmosphere and put a plug in the manifold side to prevent bad idling and by this treak it does passes emissions. Remember the cylinder head needs those harmful gases to escape or you will create serious damage to the head. GOOOOD luck

lol im glad there not in MN either... i would def. fail being i have straight pipes from the exhuast manifold. lol then a high flow "muffler" lol they would just laugh at the results

Many times if you fail, but just bairly, a tune up/fixing the car as recommended will make it worse and you'll still fail...

Mine failed the e-test here in ontario. I had to replace the EGR valve and cat converter. Cost me like 500 CAD total.

borhan11 wrote:Thanks for your reply
That for sure is one of the problems, but I should still be able to pass...


The question I have now is

"Could it be that my new CAT does not react VOC's (hydrocarbons) and only reacts CO's and NO's since it was a cheap generic cat 'Walker Economy'?"

because my CO was reduced by 50% and my NO was reduced by 90%, but the HC stayed where it was....

IF the answer is that all Cats do VOC's (hydrocarbons) then it could be my stock O2 sensor not letting enough oxygen get out to react w/ VOC's...


Your thoughts guys...

Thanks

Borhan

Well Hyrdocarbons are gas pariticles. If your new cat can't combust enough of them then you are making A LOT! A CATalytic converter is full off ceramic "walls" that allow gas (the state not the product) to flow through. There is also a bit of platium inside. This superheats the existing fuel left in your exhaust. If you wanted to be sneaky you could try unpluging an injector. You may throw a code, but it will produce less hydrocarbon emissions. It will also run rougher. You may want to check for codes and definately do your own compression test and see if you can get your compression back up (170 across the board). Good luck and keep us informed!

Rule of thumb:
CO - Good (just from the combustion of fuel)
NOX - BAD (poisonious gas that's more abundant when running lean)
HC - Bad for Emissions Testing (Unburnt Fuel Particles)

[quote="Mazda_Power"]
If your new cat can't combust enough of them then you are making A LOT! ]

Or (more likely) you aren't buring what the motor is supposed to.