PunkRudeBoy

So my Civic is still having smog issues. At first my readinesses monitors didn't clear, but my emissions were good. Now my monitors are passing but my emissions is failing. I've changed out my cat for a new one, so what can be holding me back now 02 sensor?

d16y8
Aem Cold Air
DC Headers

PunkRudeBoy

Just shelled out for new plugs, wires, and cap. Guess we"ll start there.

TwoFaced

That's a good start...those are things that should've been changed anyways so good start...post results and we'll go from there.

Former User

The O2 levels are high, suggesting that the engine is running rich due to an exhaust leak near or upstream of the primary O2 sensor.

PunkRudeBoy

I was thinking of taking it back to the muffler place after you mentioned this. Maybe one of the welds when they installed my cat didn't hold up?

PunkRudeBoy

bump

Former User

Did you check for an exhaust leak from the header or exhaust pipe A?

flush_EJ1

That much O2 should not be left with HC and CO levels so high. Those are like 18:1 levels.

I'm going to say there is an exhaust leak too. The O2 level is saying lean misfire the HC and CO say rich mixture. The fact that NOx is so low also indicates a lot of fuel in the combustion chamber, keeping the temps down.

PunkRudeBoy

Went and took it to the family mechanic the other day. Turns out the timing belt was off 2 teeth. Had them to do the repair and they found some fan/ac belts getting cracked so they replaced those as well.

After 5 months or so of hell it looks like it was my lucky day cuz I passed! Vehicle is now registered.

Former User

Sorry buddy, but your explanation just isn't adding up. How could your car possibly pass the ignition timing test if the mechanical timing was off by two or even one tooth? And the engine most likely would not run or would run so poorly that you would be unable to drive to the inspection station if it were off by two teeth. Your mechanic is not telling the truth.

PunkRudeBoy

I can post the service ticket. The cars running better and doesn't idle as rough. What would cause the drop in my HC numbers this time around? I'm also curious why my NOx shot up. Not being defensive just asking questions.

Former User

Under normal conditions, there's a reverse relationship between HC and NOx. When one goes down, the other goes up.

What I am saying is that it is impossible for the ignition timing to be fine if the mechanical timing is off. What's printed on your emissions form in the first post and what your mechanic's diagnosis was are completely inconsistent.

PunkRudeBoy

I get what your saying. I'll look further into it. I'll check for an exhause leak at the place that put my cat in next week. My wallets taken a beating and needs a break. I'm gonna be pissed if I paid 250 bucks and simply got lucky.

Former User

The emission test results say your problem is gone, so I don't think you currently have a cat or exhaust problem -- just saying that something does not add up.

PunkRudeBoy

I do appreciate yours as well as everyones advice on here. Thanks again.