P1093 2006 X5 suggestions?

[mendes9]

Hello, looking for suggestions on a P1093. I'm a DIY mechanic, with some knowledge. Yes, I've searched for this code on many forums. A little history and then my diagnosis. P1093 is a rich condition for Bank 2.

1) Car has 196K miles, the only recent change of any kind before this code popped and goes away sometimes was change in oil type to Valvoline 5W30 restore and protect (3,000 miles using this oil).
2) Code does go and come, but seems to be staying on more recently.
3) I have autel mk808 and ISTA, used these scanners, and I can see why it's throwing the code.
4) All oxygen sensors appear to be responding fine. I have replaced Bank 2 downstream oxygen sensor just in case, which didn't make a difference.
5) About the pic below, graphs are for S1B1, S2B1, S2B2 (I do show the value for S1B2 .77 volts). Autel scanners unlike launch can't show a bunch of multiple individual graphs, and on my mk808 I can only show 3.
6) The graph shows that S2B2 oscillating, and S1B2 (highlight with .77 volts) is always steady. S2B2, when not isolating will also be very low like .1 or .2 volts indicating lean. So as you can see since S2B2 is reporting lean the DME is pouring more fuel, look at the top graph S1B1, vs the 2nd graph S2B2, S2B2 graph has much level saw tooth graphs, hence the code.
7) So why does the code sometimes go away? In graphing this for example, sometimes I will raise the RPM to 3,000 and then all the sudden the S2B2 voltage matches S1B2 and acts completely normal. This is what's baffling.
8) From the data it suggests a failing catalytic convertor on Bank 2 since it's oscillating, but what has me going is that why wouldn't it be constant. Again, in testing yesterday if I raise RPM to 3, 4K rpm then it's normal.


What I've tried:
1) Replaced downstream Bank 2 O2 sensor, no change.
2) I've seen other posts claiming to solve this and other never solving it (one person gone so far as to re-program the DME not to run this test). I've smoked tested from intake and from rear tail pipe. There are no leaks on intake and no leaks on the exhaust before downstream O2 sensor.
3) Rest adaptations, I've seen posts on where the resolved it didn't work here.
4) I may do an injector drop test to see if maybe I have some leaking injectors but the data doesn't suggest that to be the issue, the data shows a lean condition on the downstream O2 hence the computer is pouring more fuel.
5) I've seen other posts where swapping down stream, or upstream sensors, not sure about that or how that could help unless they were wrong and mine are not, again 196K and these are the 2nd set of O2 sensors replaced originals at 100K (Bosch OE BMW)

Any suggestions would be appreciated as a catalytic converter on this car may be a death sentence and I really enjoy the car.

[80stech]

Most likely a vacuum leak.

[X5chemist]

Is the fuel pump original? What is your fuel pressure at idle and ~2000 RPMs?

[mendes9]

Originally Posted by 80stech

Most likely a vacuum leak.

No vacuum leaks, I smoke tested. There was a very slight leak at throttle body, but tightened clamps no vacuum leak. And if I did, why would it effect Bank 2 only?

[mendes9]

Originally Posted by X5chemist

Is the fuel pump original? What is your fuel pressure at idle and ~2000 RPMs?

Fuel pump is not original, it's the 2nd. I will do a pressure test, and verify but why that would effect bank 2 only, would be interesting, but never the less I will test it.

[80stech]

A smoke test can help to find a vacuum leak but doesn't mean that there is no vacuum leak if you don't see smoke. Kinda a "negative option" thing. Since the crankcase ventilation is closed any part of the crankcase (including pan gasket and rear main seal) can leak air in. The intake gasket itself is rarely the source of the leak and there are lots of dynamics involved as to why only one cylinder triggers a code. Vacuum cap at the back of the intake and the brake booster would for example be good places to look for bank 2 but that doesn't rule anything else out either.

[mendes9]

Update:

1st thanks for all the suggestions. 2nd, I swapped downstream O2 sensors. What I expected to see what lean condition on Bank 1 downstream O2. That's exactly what the scanner data showed. I also cleared the codes, note that besides the P1093, a new code appeared forget but it was a pending code for a misfire (due to low fuel or something like that I forget). Ok, after a short trip, P1093 came back, and this was surprising as it still complained about bank 2. I was expecting a 1092 or whatever the code is for the same issue on bank 1, but it was still bank 2!! Again this was surprising. Ok, at this point I'm suspecting maybe the upstream O2 sensor on bank 2 is bad even though at times the downstream O2 sensor for bank 2 is reporting lean? I ordered an OEM Bosch sensor, and installed it on Bank 2. I haven't had time to look at scanner data to see if it's made a difference, but I've gone on 2 shorts drivers and the code hasn't set it, fingers crossed. I will report back, as maybe this could help someone else.

[Factory6speed]

Is this the m54 or one of the v8s? It's not uncommon on the six cylinder cars to see injector 5 in particular develop a leak. Did you ever hear any pops or backfires of sorts in your exhaust. If it were me I would probably swap injector 2 and 5 see what happens. Or just do the whole bank.

I replaced my o2s at first when dealing with lean codes but I don't think they really go bad. It was due to vacuum leaks from the disa and the caps for that pump on the back of the intake manifold. But that was lean codes. For too rich I like what you're thinking with injectors. It could also be the maf.