Can we reset "adaptation, mixture"?

[kevinkay]

Trying to figure out my Service Engine soon P1191 (Oxygen sensor too rich before cat. bank 2). Car runs fine. replaced tank breather valve (was getting an additional error on that originally) Cleaned up MAF, idle control valve, DISA seal is good, gas cap is tight. DMTL motor is working, cant find any air or vacuum leaks. Ruled out injector leaks as I switched them from bank 1 to bank 2 and still rich error ONLY in bank 2. Inspected and cleaned spark plugs.

Checked the adaptation mixture values and see they are different between bank 1 and bank 2. Do they constantly adjust or can we reset them?
Is it ever the case that we clear the "service eng. soon" too quickly and it returns because the car has not adjusted to the new or cleaned parts?

Thanks

[80stech]

Idle mixture values represent what the DME needs to do to try and get the mixture right as reported by the oxygen sensor. While on most cars they are somewhat adaptive to where they last left off but they should correct fairly quickly if the problem is repaired. If you are pretty sure that you have ruled out a vacuum leak I would maybe check fuel pressure. Just because the code only comes up on one bank doesn't necessarily mean the problem isn't common to both. Maybe someone else can verify if the idle mixture numbers are ever very close to being the same on both banks even when everything is operating properly? Or is there always some differences in the CCCV flow and other factors that make them different?

[80stech]

Also if Oxygen sensor is reporting "Oxygen rich" it means that you are "fuel lean"

[upallnight]

Originally Posted by 80stech

Also if Oxygen sensor is reporting "Oxygen rich" it means that you are "fuel lean"

If the fuel trim shows a positive value that means the 02 sensor is reporting a lean condition.

If the fuel trim shows a negative value that means the 02 sensor is reporting a rich condition.

[DSSA]

Originally Posted by 80stech

Also if Oxygen sensor is reporting "Oxygen rich" it means that you are "fuel lean"

Actually the opposite of this. When you receive an O2 code for "too rich", it means that the FUEL content (un-burned) is higher than parameters set in the ECU to signal the condition.

I don't work much on the BMWs that I own. I'm older, not as "in need of performance" as I used to be, have enough modified (and occasionally) headaches already, and they're decent enough performing for my needs as "everyday cars". I have customers that I do minor work for one their BMWs (suspension, exhaust, intake, light electronics, etc.), but I'm not building engines/transmissions, nor doing hard coding on the DMEs.

I note that as a basis for my knowledge level on these cars, as is not as extensive as with other marques, yet a majority of the knowledge transfers over (some particulars as in BMWs DME code are where I'm not professing expertise).

I would research these two facts, but I'm pretty confident in them being correct.

1) The DME will reset both short-term, and long-term fuel trims (learned values in fuel adjustment from the base fuel mapping) if the power is removed (disconnect a battery, wait a little bit for the capacitors in the car to leak down voltage, then re-connect).

2) The E53s still use a 1 volt, narrow band sensor (as opposed to the newer cars with 5V wide band sensors).

That said, if you have a sacan tool that will allow you to read sensor values, I would warm the car up to operating temperature, shut it off, and reset the DME via the battery disconnect. Wait a few minutes for the capacitors to leak down, reconnect, start it, and read both front O2 sensor readings with your scan tool (Bank 1, Sensor 1 & Bank 2, Sensor 1---may be listed just as "B1S1 & B2S1" on your particular scan tool). Watch the values for a minute or two, and see if they're way off from one another in voltage (0.00 volts to 1.00 volts).

Then allow it to idle for 10-15 minutes to see what the Long Term Fuel Trim (or learned fuel trim percentage--the phrasing can differ per scan tool used) is, and then check the Short Term Fuel Trim (STFT) to see if it has settled down into the +/- 8% range.

This will give you a baseline to start with.

As others have mentioned, vacuum leaks, etc., can cause issues, however, that will typically cause a condition shown on BOTH banks at that point. If you can find the TSB on a working page that the gentleman above pointed out, I would also research that.

The above said, the "typical" things to cause one bank to be rich, and the other fine (using your baseline values above for comparison) are:

1) A bad/fouling spark plug.

2) Weak Coil on one/multiple cylinders (I've already dealt with this on my 60K mile 4.4)

3) Dirty/faulty injector. The spray pattern can go from "Mist" to "Stream" with very little dirt, and/or have the the injector never completely "seal" between pulses.

4) Valve seal leaking, and introducing oil into the cylinder

5) Weak compression in a cylinder/cylinders on that bank (valve seats, rings, etc.).

You'd probably notice a decent "oil burning" smell on those last two.

It's good that you swapped the O2s to start with, ruling out a bad sensor.

It's all just a matter of diagnostics/ruling out what *isn't* wrong to narrow the possibilities.

Do the easy stuff first.

Josh

[kevinkay]

Thank you.
I am not sure I have ruled out a vacuum leak - only that all hoses that I can see and think are vacuum lines look OK to me. Recent CCV replacement, cold climate.
within the the afternoon, I reset the error. Swapped the spark plugs and coils from 1-2-3 to 4-5-6 and error returned once again P1191 bank 2.
My mind I was thinking its too much fuel, always associated "rich" with fuel but DUHH...its the "oxygen" sensor reporting.....

Is there any tests for vacuum leaks?

My error sometimes stays off for several days/trips and they sometimes returns quickly (2 short trips) usually just as car is at warmed up temp (between cold/hot on the gauge). It may be returning quicker when the gas tank is full.

I am very much an amateur and stumble through and sometimes rely on my own misguided logic rather than knowledge. I am scared thats its a major valve/cylinder issue because it keeps coming up only in bank 2.

Any possible chance it could be as simple as an air filter? Just looked up when I replaced it about 30,000 miles its an off brand (looks fine).

THANKS!

[80stech]

If you don't feel you have ruled out vacuum leak then I would go back to that. Check as much as you can again, intake boot, hoses on back of manifold, brake booster lines, DISA o-ring(I'm assuming you replace it?) purge hose(front of manifold) etc. You could try a smoke test, I've never done one but looks like it works pretty good.

[kevinkay]

thanks for staying with me....
intake boot, completely went over - all good
hoses on back of manifold, intake or exhaust? (any rubber hose that I could see I ran my hand across)
brake booster lines,Did not check this - will tomorrow
DISA o-ring(I'm assuming you replace it?) Replaced some time ago, had to give it a good pull to get it off, not flattened and felt confident it was tight
purge hose(front of manifold) humm...replacing the purge valve I did give a good tug to the hose that goes under and towards the exhaust manifiold - cant see where it ends, could I have pulled this off????

[X53Jay4.8is]

Originally Posted by kevinkay

thanks for staying with me....
intake boot, completely went over - all good
hoses on back of manifold, intake or exhaust? (any rubber hose that I could see I ran my hand across)
brake booster lines,Did not check this - will tomorrow
DISA o-ring(I'm assuming you replace it?) Replaced some time ago, had to give it a good pull to get it off, not flattened and felt confident it was tight
purge hose(front of manifold) humm...replacing the purge valve I did give a good tug to the hose that goes under and towards the exhaust manifiold - cant see where it ends, could I have pulled this off????

Smoke the vehicle to assure that you do not have a vapor leak first

[80stech]

OK, no problem I wish someone else would chime in about my question concerning the idle adaptation numbers... anybody ???