Cross-Hair

Hey guys, I've got a problem. I just took my emissions test and failed. Recently (before the test) I had a crack in my exhaust manifold (/cat) and had it replaced with an aftermarket replacement part. I still however get a check engine light pop up once in a while (I made sure to reset the ECU before emissions, hoping it would still pass). The code is always p1047

Anyways, I failed and could use some help. I've had it tested twice now (the second was free within a period of time so I figured I'd give it another run).

My results are attached.

I'm hoping someone can figure something out and give me an idea where to look to get this fixed. I'm thinking it might be one or both of my O2 sensors. My car is at 165k miles and I believe they were both replaced at about 90k miles (not at all sure about this). The O2 sensors are supposed to read ~.45V if the mixture is a perfect A/F ratio and is supposed to read higher if it's richer and lower if it's leaner. The thing that confuses me is how low the readings are for sensor #1 (pre-cat) , yet so high for sensor #2 (post-cat).

Any ideas?

In both cases, I failed because my hydrocarbons were too high (twice the limit), and my carbon monoxide was too high (eight times the limit).

My other concern is that I might have reset my ecu too close to the inspection. I literally reset my ECU and then drove the **** out of my car for about 10-15 minutes to get the catalytic converter warmed up. Was this a bad idea? I've heard that it takes a few days for the ECU to re-adjust... the problem is that my check engine light also turns on after a few days.

I took the test again (the second set of graphs). And the data looks a little more reasonable, but I failed a lot worse. For this time, the ECU was not reset before the test (the CEL was still off though). I did however had premium fuel... I know I'm not supposed to, but it was suggested to me to try using a higher octane fuel.

Anyways, my car is a 1996 Civic LX auto 4 door. It has nothing aftermarket done to it except using a K&N filter. Also, the tranny has been swapped to an EX auto since it had problems a long time ago.

Any help would be appreciated, but try to be as detailed as possible.

Thanks.

Cross-Hair

Anyone have any suggestions? Any help is appreciated.

Cross-Hair

Well, no one ended up helping me, but since then I got my problem solved so I figured I'd post my findings in case someone had a similar problem.

I figured my problem had something to do with my O2 sensors. I chatted with a buddy of mine, and he thought it might have been the second O2 sensor. I replaced the sensor and tired the test again. I failed... and decided to get the car looked at by an emissions specialist.

Before he did any work he looked at my tests and said that it was my first O2 sensor (and didn't know why I changed out my first one). He said that in all of my charts, the first O2 sensor was always very low, and never got above the .45V mark (perfect A/F ratio) meaning it was the one that was messed up.

He said that the second O2 sensor also gave messed up readings, but since it was able to go above and below the .45V mark, and generally read high (makes sense since I was running super rich - high emissions) that the sensor was probably working.

He asked if I wanted him to look at the rest of the car and see if he could find anything else in case that wasn't the issue. I let him since I was sick of dealing with the problems and wanted it to be fully done.

He charged me about $105 labor + $90 parts (O2 sensor) + $25 emissions (which he would have comp'ed if it had failed). Overall, the work cost me a little over $200, but I passed with flying colors.

I just wish I had replaced the proper sensor in the first place and saved myself some cash. On the bright side, both of my sensors are now new and I shouldn't have any more problems for around 90k miles (if my car makes it that far).

Anyways, I hope this helps someone.