MX-3.com

Any idea what could be causing the high NO emissions? On my smog check, both HC and CO emission passed fine, but NO was double what the Max allowable.

All visual/Functional checks were all good too..

Thank in advanced.

Phil.

Ha,ha you mean Oxides of Nitrogen or NOX.

Any way, NOX is controlled mostly by the EGR function of the emissions. Another controller of NOX is the cat. converter bolted downstream of the exhaust. How long has it been since the converter was replaced? Usually they have an average service life of about 80,000 miles. Make sure the EGR is functioning properly as well.

In most cases, a good tune up is all that is needed....You may have allready done that though.

ah yeah, that's it. =p It read NO (PPM) on the smog test report... I know what PPM means.. but assumed NO was called nitrus oxide lol. I figure those of you who knows more about cars would know what i was referring to anyway. =)

So you are thinking it's either the EGR or Catalytic Converter... I bought the car 2nd hand at 118k miles and this is the first initial smog I need to do.. No clue if the Cat Converter was ever replaced.. but if you say the lifespam is around 80k, it might have died...

The EGR... not sure what that is... sounds like the EGR is something a tune-up will take care of? or is it something that needs to be replaced?

I did have a 100k service done just the other day which included oil change, tune-up etc. Not sure how good a job they did for the $80... but yeah, the smog still failed after that.

I'll do some search on catalytic converter. hope it's not too expensive to replace. =)

Thanks for the response Jaydog. =)


Phil.

A tune up would consist of new spark plugs, wires, disty. cap, rotor button, sometimes a fuel filter, idle speed check, and most importantly an ignition timing check. (9-11 deg. BTDC)

If the factory converter is still on it, now would be a good time to replace it. A quality muffler shop should be able to do it for under $300.

Assuming you have a 94+ model, then you could do an EGR check from the shop manual listed on the main page of Mx-3.com. A hand held vaccum pump is all you would need to make sure it's working like it's supposed to.

If you have a 92-93 RS, then don't worry, the car didn't have EGR from the factory.

Yeah, mine is a 92 GS so I guess it's probably the catalytic converter then... yikes $300... I did a search online, the part itself is only around $110 for the 92 4cyl Mx3.

Wonder if it's something I can do on my own once I order the part... or maybe the labor won't be more then an hour or so..

Appreciate the help Jaydog. You rock! =)


Phil.

Yo!

From what I hear there are 2 cats on the MX-3's One custom one right after then engine and another universal one before the muffler. The universal one on mine was cracked open and rattling at 110K and I bought a cheap one for 52$ ship included from parts america and I had a muffler shop put it in for $40.

I had a smog before and I just had one and it took my NO down from 447PPM to 37PPM at 15mph. I did it to help my HC but it did not =(.

Still trying to pass HC.

Hope you find the info useful

Borhan

so there are 2 Cats... is there an easy way to find out which one might be the one that failed...? other then take it into a shop. I don't really have any mechanics that I know/trust...

or maybe just change out the cheaper one and hope that's the one..? =p


Phil.

borhan11 wrote:Yo!

From what I hear there are 2 cats on the MX-3's One custom one right after then engine and another universal one before the muffler.

Huh??..there is only one cat. on the v-6. There are two on the 94+ 4cyl's.

Ok so I have a link to the manual here

http://www.mx-3.com/95manual/F1/F1-127.gif

the first one is called the "Warm Up 3-way Cat" and the next one is called just a "3-way cat"

Phil, they both pretty much go bad after about 120k, and a new cat is always better than an old one. If you're just worried about smog, go ahead and change the universal cat it should reduce your NO significantly.... but make sure you go after at least 15-20 miles of driving so the cats are hot and can oxidize properly.

Borhan

Thanks Borhan,

I'll go ahead and change out the 2nd and see what happens... or should I bother having a shop run a diagnostic to see what the problem is first?

Both you and Jay pretty much convinced me that the Cat is dead... that first 3 way warm-up thingy might also be dead.. but hopefully getting a new 2nd cat. will take care of smog.

Still love the mx-3, but it's getting old and problems are starting to come up. Maybe time to sell it and get me a truck... or get a new paint job for the mx-3, keep it AND get a truck heh

Thanks for the help guys.


Phil.