Oxygen Sensor BMW 002963

[dworthy]

So one of the few times I tend to post here, as I have found little to no info on this BMW Code:

002963 - Lambda probe before catalytic converter bank 2: Dynamics

So what the car is doing (2005 325it), under heavy load, ie getting onto the Autobahn I will get what feels like a miss-fire. The motor is skipping a beat and down on power. At close to 160k miles, this would be expected time for a VANOS rebuild, however in live data what the DME commands, the VANOS is doing. So I started to dig deeper and watched the STFT on both banks. Normally they should be pretty close to each other, but in this case on acceleration, I would see bank 1 at +7% or so, and bank 2 would drop to -27% then jump to +10% or more. This would bounce back and forth for a couple of second as the rev counter hits 3k or more.

At times when I run it out to 4.5k or more I run the risk of the motor going into limp mode with a Beep and EML, Traction Control and Brake all in yellow. Those lights lead me down a rabbit hole that I don't want to go down again, so I pulled the above code.

I think replacing the sensor should do the trick, as it only has been in there for about 80k miles and about 7 years, but am thinking about doing both. The post cats have been in there for about the same amount of time, but with the age of the vehicle I will just wait on those.

So just to update this thread with the symptoms:
1) Drop in fuel mileage
2) Drop in power by 10%-20% according to the butt dyno
3) Missing/hesitation on Part throttle to 80% throttle after 2.5k RPM, goes away at WOT
4) No SES or EML light is on.

[randy72877]

Your symptoms sound exactly like you have a clogged catalytic converter. Huge bank to bank difference in fuel trim, loss of power, and limp mode at high rpm. Test backpressure or try running it with the pre cat o2 sensors removed.

Sent from my S61 using Tapatalk

[MarcoZandrini]

Hmmm, isn’t it a bit odd that only 1 converter could be blocked? I would think that both would be bad.

Darin, how quickly does the bank 2 STFT change? Does it behave normally when putzing around town?

[dworthy]

Anything below 50% throttle, or under 3k it's pretty much normal. As far as the changes, they can pretty wild when I hit 80% throttle or engine load, but only on Bank 2. This is why I am leaning more towards the bad oxygen sensor and not a clogged cat.

[randy72877]

Anything below 50% throttle, or under 3k it's pretty much normal. As far as the changes, they can pretty wild when I hit 80% throttle or engine load, but only on Bank 2. This is why I am leaning more towards the bad oxygen sensor and not a clogged cat.

Swap the pre cat o2 sensors bank to bank and see if the code/symptom follows. I hope for your sake I'm wrong. It's a lot easier to replace an o2 than cats. But since you only have problems at higher load and rpm, it's likely that you have a restricted cat. Probably bank 2. At higher load and rpm, there is more exhaust volume that has nowhere to go when a cat is clogged. That causes back pressure to spike. When half the engine can't breathe, the DME gets very confused. A bad o2 sensor would not likely work fine at lower load/rpm and not at higher load/rpm. Back pressure is easy to test on this engine if you take out the pre cat o2 sensors to swap them like I suggested.

Sent from my S61 using Tapatalk

[dworthy]

Will give that a try, but just as an FYI I am pretty much over maintaining my cars as they have never broken down on me before. Most of the wear items get replace before they go bad as I don't like sitting on the side of the road waiting for a tow truck.

[dworthy]

So on the way home from work yesterday, I was observing the STFT again on Bank-2 it would go to Zero at coasting in gear, and as soon as I get on the gas pedal it would go to -28%. The next part is interesting, as after a bit, the bank 2 STFT went to Zero and the car no longer jerked/missed at load. While it seems to be down on power some, it wasn't the same as before.

I am going to throw a oxygen sensor at it, for that should fix it.

[dworthy]

So just wanted to close the loop on this thread. Installed the new pre cat oxygen sensors on both banks, and after 125 miles of driving the jerking/missing is gone. It still feels like it down just a touch on the power band, but after several rips to 125 MPH, no beep and EML, TC, Brake light coming on. I will take another look at the VANOS again, for it used to really come alive at 5k RPM's, but it seems a bit flat now.

[MarcoZandrini]

125mph-nice! Here in the states that’s land you in the pokey fir a month! A few years ago we had the star of the local MLB team get cause doing 135mph in his Porsche on the beltway. He spent 15 weekends in the county jail.

[dworthy]

That's the beauty of the Autobahn, most if it has no limit

Will be doing some more testing to see about getting the rest of my ponies back.

[dworthy]

Now that I have driven over 500 miles, the car doesn't like to accelerate under WOT much anymore so I decided to look at the fuel pressure. What lead me to that was a misfire on #3, then #1, and a fuel mixture fault for lean BMW Code 002883. The fuel pressure holds steady at 50 PSI even when the car is reved over 5k under load, but what I did hear is a VANOS rattle after 3k. So that tells me I have to rebuild it in my near future, but I think I will pull one from a junk car so I will have less time off the road with the car.

The VANOS may have been rattling for some time, but I didn't hear it until I removed the cabin filter and housing, then the noise was able to make it into the cabin. I had to do that to access the schrader valve on the fuel rail, so it's good that I tested the fuel pressure, otherwise I wouldn't have heard the rattle.

[dworthy]

So going to update this thread, rebuilt the VANOS this past weekend, while that fixed the lower end, I am still having issues with getting to the upper end of the rev range. On my way to work today, going up a rather steep hill in 5th gear at 70kph with about 2k rpm's it started to struggle and the beep with the 3 lights came up. So I am going to throw in the towel, and put some cats in. I think what has happened for the last 100k it has been burning a liter of oil every 2k-3k miles and I feel that has clogged the cats. I have a used set that I can install for something told me this is where I will have to end up anyway so lets see if that will fix it.

I think in the end I was having multiple problems and issues, I have fixed the easiest first which would have been normal maintenance anyway, now onto the hard stuff as I am not looking forward to working in that tight space for the cats.

[dworthy]

So I am going to close out this thread with this:

The cat's were replaced and after inspecting them, they were about 40-50 percent clogged. I don't know how I never got a cat efficiency code to populate, but after replacing them the car runs great.

The cat's I used were Borsal, and the fit/finish were okay. The bank 1 pipe is touching the bank 2 cat, and it moved the mid pipe connectors over to the point I could no longer use the factory support from the transmission. They were also not even at the connectors either, but it still sealed anyway.

I was getting a lot of different codes from miss-fire to air path for the MAF to mixture codes. In the end, it took out the secondary air valve as the exhaust gasses clogged it up.

I also noticed that after the first fill-up my MPG has gained by 20% and I will see with this next tank if I can get better than the 24 MPG average I have been getting as of late.

[dworthy]

So last post, I promise!

I switched the 3.46 diff out for a 3.07, that makes a big difference on the autobahn! Something else I have noticed too is that it takes longer for the car to get to operating temperature, and the engine doesn't have to work as hard as before. Went for a long drive of about 275 miles and filled up. My average speed was 65 mph and my average MPG was 34.9 calculated at the pump. The best I had ever gotten before that was 31.9 MPG with an average speed of 54 MPH, and that was back in 2006. I think these cat's are a higher flow than the U.S. ones but they are still certified as EU-4 cats, not sure how that would compare.

As for the top speed, it's up to 130 MPH instead of the 125 before and I am only at 5.5k RPM instead, thinking of removing the governor just to see how fast this car can really go now.