Newbee has P1192 bank 1 post cat fuel trim

Im a newbee to this forum and want to thank all you experts. I'm a good Ford mechanic, but these BMW's are a different breed.

I have an 01 e39 525 with 110k mileage. I've recently received a P1192 cel. Car runs great, no stalling or stumbling idle is fine. Would not know there is an issue, other than the cel.

Question; I've read thousands of posts on P1192 and no clear fix. Does P1192 indicate a failing O2 ? Because I've already changed. Or is it a fuel trim issue (air leak) somewhere ?

I have a scanner that shows 02 voltage, and short term/ long term fuel %

I have no reference to know if the data I'm seeing is good or not

Ease help

You've already changed the post-cat sensor?

Bank 1 post cat O2 was changed, 15 miles later cel came back same code P1192

Did you scan the voltages and fuel trim values?

No I didn't. Is there a DIY for that ?
But my code scan reads O2 voltages.

Live data before cel
Load 22%
Shrtft1 % 6.3
Shrtft2 % 4.7
Rpm 1937
Mph 55
Maf 2.37
Tp 22%
O2 1-1 v 0.130
O2 1-2 v 0.810
O2 2-1 v 0.175
O2 2-2 v 0.745

CEL triggered
Load 5.9%
Shrtft1 % 0
Shrtft2 % 0
Rpm 1969
Mph 57
Maf 0.657
Tp 0%
O2 1-1 v 0.0
O2 1-2 v 0.0
O2 2-1 v 0.0
O2 2-2 v 0.10

I don't know what a healthy engine is supposed to look like.
Have real time data but can't download.

Looks to me like the values after the CEL triggered indicate you're in open loop, so the O2 sensors aren't used for setting the fuel trim. That probably doesn't tell us much.

The front O2 sensors are indicating that the mixture is lean. The short term fuel trim values both indicate that the system is increasing the injection pulse to correct a lean condition. If I understand the situation correctly, when the STFT hits 8%, it adjusts the long term fuel trim. When the LTFT hits 12% the DTC is set and the CEL turns on.

Do you have the LTFT values?

I'm not sure how to interpret the post catalyst O2 sensor voltages. I thought they are supposed to be about 0.450 V.

I guess this tells you that the engine is running lean. Yous should probably look for air leaks. The lower intake boot branch that goes to the idle control valve is often a problem, but check both boots and everywhere else downstream of the MAF.

Have you change the fuel filter and pre catalyst oxygen sensors lately?

Sorry this doesn't address you post catalyst sensor code. Hopefully someone else who know more about this will check in.

Thank you for the reply. Fords are a lot easer.

Long term fuel trim(s) always "0"

Since the cel P1192 started
I swapped the pre cats (2 to 1 and 1 to 2) no change same code
Changed outer intake boot.
I removed and inspected the DESA valve. Held vacuum and looked good
Replaced fuel filter and regulator.

This week plan to replace oil valve and all hoses.
Inner intake "Y" boot
Replace DESA gasket (Fel pro 35489)
I don't think i need to replace valve cover gasket (I did purchase one). When engine is running a small vacuum is in the valve cover, difficult to remove oil fill cap.

What an I looking for Vacuum leak ?

The ultimate driving machine is acting up

Thanks

I went out and started my 2001 530i and hooded up the scanner. I monitored the O2 voltages and found that the post cat sensors started at 0.45V and went to 0.8V when the car was warm. My car has no codes stored or pending, so I guess the values you posted are normal.

If your LTFT is 0 ms when the system is in closed loop control, then the car shouldn't throw a code for that. So I don't know what to tell you.

Anyway, I'd suggest you check the lower intake boot carefully. If that "oil valve" you're getting ready to change is the CCV, then you'll defintiely be taking off the boot for that.

On my 97 the icv can tilt and make a gap in the fit to the manifold, maybe check for that. I agree STFT adding fuel, like vac leak or dirty maf. Watch the STFT in real time, see if it's switching like once per sec or faster for normal. At idle there's more vac, Leak is more issue then.

I want to thank you folks for helping me with this issue. If its a vac leak, sooner than later I'll find it ( I hope).
Yes the oil valve is the CVV or CCV.

What are the normal components or hoses that fail, what should i look at first.
I have (and will) change the hoses from the MAF to the TB. What else

Thanks

Replacing the CCV and inspecting the intake boots will probably catch most of it. You might want to read this thread for other vacuum leaks.

I don't know if fixing all the vacuum leaks will fix the P1192, but you should fix them anyway.

Steve530, that's what I'm using as a guide for vacuum hoses. The intent is to start with Y hose and CCV and go from that point. Seems to be pretty easy, get about 10' of 3.5mm hose ~1/8" Hose and start replacing.

If you have any other directions, I could use em

As I understand it
The higher voltage on the O2's, the more oxygen (lean condition) I have.

The lower the voltage the more fuel (rich)

Yes ?

Yes

The manifold is bolted to the head, maybe check if nuts snug else vac leak. Again if vac leak, would be worse at idle since butterfly choking off air. I would first crc the maf. Also swish icv in zip bag of 70% alcohol.

I think it's the other way around.

As I understand it, the oxygen sensor generates a voltage proportional to the difference between the oxygen content of the exhaust and the atmosphere. If there is a large difference in the oxygen content, the sensor produces a higher voltage. If the difference in oxygen content is small, the voltage produced is small.

When the mixture is rich, most of the oxygen is used in combustion. So the oxygen content in the exhaust is low and the difference between the oxygen content in the exhaust and atmospheric oxygen content is high. The oxygen sensor produces a high voltage, like 0.6-1,0V.

When the mixture is lean, there is more residual oxygen in the exhaust. The differential concentration is smaller and the oxygen sensor produces a lower voltage, like 0.1-0.4V.

This document has a good explanation of the operation.

Originally Posted by ztom

The manifold is bolted to the head, maybe check if nuts snug else vac leak. Again if vac leak, would be worse at idle since butterfly choking off air. I would first crc the maf. Also swish icv in zip bag of 70% alcohol.

While you're replacing the CCV, it would be a good time to clean the idle control valve. IIRC, some people have damaged the ICV by getting the cleaning solution in the electronics. I think I just used MAF cleaner or Carb cleaner and a rag. It might be good to look for a DIY for the ICV.

I use alcohol fine. Watch the o2 real time when you let up the pedal, V goes high lean.

From Wikipedia:

The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. An output voltage of 0.2 V (200 mV) DC represents a "lean mixture" of fuel and oxygen, where the amount of oxygen entering the cylinder is sufficient to fully oxidize the carbon monoxide (CO), produced in burning the air and fuel, into carbon dioxide (CO2). An output voltage of 0.8 V (800 mV) DC represents a "rich mixture", one which is high in unburned fuel and low in remaining oxygen. The ideal setpoint is approximately 0.45 V (450 mV) DC. This is where the quantities of air and fuel are in the optimum ratio, which is ~0.5% lean of the stoichiometric point, such that the exhaust output contains minimal carbon monoxide.

You're right, high rich.

Thanks I have a better understanding. In my post I identified before and after cel by frame. I'm looking at the throttle position (before and after) it went from 22% before cel to 0% at cel. Could this trigger the cel, or did the computer assume 0% when it goes closed loop.

Lean means too much air and/or not enough fuel. MAF ? Fuel pump ?
At idle the fuel pressure is 52# is this correct pressure ?

Strange purchasing all the parts to replace a majority of the plastic parts including gaskets and oil separator.

Decided to throw some injector cleaner in the tank while waiting for the other parts figuring at this point couldn't hurt. That was about 60 miles ago, light has not come on since then. In the past every 12 miles id get a P1192 w/cel Go figure