Whats up with my car.

[95MPOWER]

I have a 1995 M3 intake, track pipe, exhaust and chip. When I went to get it smogged I took everything off except the intake. I failed. I checked the spark plugs and they were brownish/red/black so i thought the car was running too rich so I changed the 02 sensor. Took it back and it still failed, but the numbers did improve. There are no fault codes comming up so what should I do guys? Could it be an air flow meter in the process of going bad?

 

[bahnstormer]

u put the stock chip back in?

 

[epj3]

Well, the plugs shouldnt be black, but being brown or tan in color means it's running with a good fuel/air mixture. The chip would be the only thing setting it off, if not then the catalytic converter is probably bad. Also check to make sure you're using the correct grade of gas. If it says to use 91 octane, dont use 92 or 93.

 

[95MPOWER]

stock chip was used. I use only Chevron 91 octane. My car only has 87k on it so I dont think the cat can be bad...or could it?

 

[epj3]

Oh it could easily be bad. Did you run the car with the chip and the cat at the same time? The engine will run a little hotter with the chip than without. I saw you said you use a track pipe, so i assume you didnt have the cat on for too long.

 

[95MPOWER]

About a month after the chip was put in, the borla race exhaust, which has a track pipe was put on. You guys think it could be the air flow meter going bad? When I listen to the exhaust, I can hear a stumble in the exhaust note as my brothers prelude (aftermarket cams) sounded. Why is there a stumble in the exhaust note?

 

[95MPOWER]

One more thing, I bought my car with the intake and heat shield already installed. There is some kind of sensor that is bolted to the heat shield that probably looks like it was connected to the stock intake somehow...could that be the problem?