Going through upstream o2 sensors

[ayang89]

like every month.

Luckly I have a year warranty on the part.

Why would this happen?

My car backfires every time at hi rpm like 4k and slow shifting into the next gear.

Or if I boost real quick n shift slow, the backfire sounds like a tire popping.

Pulled the o2 sensor and it was all black. None of the holes were able to breathe as they were covered in something that hardened overtime ( hardened black residue? )

Help?

 

[Schwamm]

I was having the same problem when my valve stem seals were bad. Oil was getting into the cylinders and then getting burned off down the exhaust. I also had a P0141 code (lean) that I'm pretty sure was caused by a loose exhaust manifold and not an actual faulty O2 sensor. If you're getting black crud on the sensor, you have something getting into your cylinders that shouldn't be there.

The backfire could also explain it if it's frequent. If backfiring messes up catalytic converters, I'm sure it can mess up an O2 sensor. Check your ignition components and make sure the plugs are gapped correctly (.028-.032)

 

[hornsfan10609]

Sounds like your car is running overly rich

 

[ayang89]

I was having the same problem when my valve stem seals were bad. Oil was getting into the cylinders and then getting burned off down the exhaust. I also had a P0141 code (lean) that I'm pretty sure was caused by a loose exhaust manifold and not an actual faulty O2 sensor. If you're getting black crud on the sensor, you have something getting into your cylinders that shouldn't be there.

The backfire could also explain it if it's frequent. If backfiring messes up catalytic converters, I'm sure it can mess up an O2 sensor. Check your ignition components and make sure the plugs are gapped correctly (.028-.032)

I'll retighten down the exhaust manifold down. My turbo seals are going out. But isn't that after the manifold? Could it shoot back up somehow? And my plugs are gapped .028-.032

 

[ayang89]

Sounds like your car is running overly rich

Unichip would fix this?

 

[hornsfan10609]

You have a problem that needs to be corrected before you mod your car. If it is backfiring that indicates the car is running rich or misfiring.

 

[ayang89]

If it was my coilpacks wouldn't it throw a code?

 

[hornsfan10609]

Not always but typically. How do you know the sensors are failing? Does it throw a check engine light? Its normal for carbon to be on the sensor but the holes should not be clogging.

 

[ayang89]

Not always but typically. How do you know the sensors are failing? Does it throw a check engine light? Its normal for carbon to be on the sensor but the holes should not be clogging.

Took it to AutoZone to have my codes pulled. It comes out bank 1 o2 sensor. So I figured since its under warranty,swap it out. Works. But then comes back.

 

[hornsfan10609]

Maybe the sensor isn't the problem.

 

[ayang89]

Maybe the sensor isn't the problem.

Just looked on my manifold. I'm missing 3 bolts. What bolt size is it? Could this be it?

 

[hornsfan10609]

That's probably not the problem but they do need to be replaced. I don't know what size off the top of my head, maybe M8x1.25 about 40mm?

 

[Schwamm]

If you're missing 3 bolts, you will be loosing enough exhaust between the head and the manifold for the O2 sensor to be getting a wildly different reading, which can cause you to run rich. I went through 3 O2 sensors in a year personally because they kept getting "fouled" and it didn't stop until i fixed my exhaust leak. Mine was not missing any bolts, so I am sure yours is worse. I ran seafoam through it and it poured out around the manifold like you wouldn't believe. Fix that, drive it, and see what happens. It might not fix all your problems, but it's definitely a problem.

The bolts are M8 1.25 I believe (double check though). I went to Ace Hardware and found some that were nearly a perfect match, flange and all, except the head was a 13mm socket. You can order them from Mazda, but they will run a few dollars each. Be careful not to over-tighten them or you will strip out the head.

 

[ayang89]

Thanks guys. Ill go to the hardware store n buy those bolts. Hopefully it fixes the problem.

 

[ayang89]

Welp update: It was my MBC that kept the light on. As soon as i took it out the light went off. But on the other hand,
I have 2 broken studs in the exhaust manifold holes, both on the outter right side of the manifold. Any ideas on how to get em out? Thats where i can smell exhaust fumes. I replaced the 3rd hole that was missing a bolt. But the other side is completely f'd.

 

[hornsfan10609]

If you cant remove them yourself you will have to have a machine shop do it.

 

[ayang89]

If you cant remove them yourself you will have to have a machine shop do it.

Gah, crap