[NiBe]

Hi,

when my car is after 30 minutes drive on highway (thus hot) and then in idle (and in closed loop) I'm having rough (shaky) idle and when I blip throttle I'm getting misfires (mostly on cylinder 2). When the car is in closed loop I'm not getting misfires nor shaky idle under the same conditions as described.

I'm also getting errors:
307D Cylinder equalization via lambda, cylinder 2
2C7E Oxygen sensor emission control
2C31 Oxygen sensor emission control

what I have done in last few thousands of km:
new aftermarket catalyst and both Bosch lambdas
new gasket on intake manifold
new high and low pressure fuel sensors
smoke test (OK)
cylinder compression test (OK)
swapped coils
new index 11 injectors
new spark plugs
cleaned MAF sensor

Any idea please?

[0l0dom0l0]

You say both oxygen sensors, but there is 4, 2 for each bank. Did you replace the sensors in both banks?

You may need a new valve cover and gasket due to CCV failure.

[SvenHz]

Is this an N43/N53 engine? Do you have INPA? Any other error codes? Please have a look at bimmerprofs if not done already. Driving warm and then idle would mean stratified fuel mode in idle which is the most critical mode for the engine. Would be interesting to, with INPA, live monitor the measurements of the lambda probes, also don't forget that the NOx sensor also reports back live lambda values.

I am not sure what you mean with closed loop vs. closed loop (typo?). I am not an expert but I believe the engine is always in closed loop except for the first 2 minutes or so after starting (when the lambda probes are being heated).

A working CCV cover is essential to the health of these engines but I seem to remember from bimmerprofs that it should only result in increased oil consumption.

Did you use the correct NGK spark plugs? (Bosch is no no for these engines!). Besides swapping the coils, have you considered replacing them? (look at bimmerprofs for recommendations).

After replacing all these parts, have you reset your injector adaptations? What is the status of your Lernbits?

If you are lost and have working INPA, consider getting an online consult from Bimmerprofs. I am not affiliated with them but have dealt with them in the past and they are very professional, knowledgeable and affordable (as opposed to a specialist that's trying to sell you time and parts).

[NiBe]

Yes, it is N43, thus 2 lambdas and 1 bank only. I have read whole bimmerprofs and I do have NOXEM installed. Closed vs closed was a typo. The engine is quite a lot in open loop, it is in closed loop only when under acceleration or when after a fast drive, then it idles in closed loop, normally in open loop. Valve cover (CCV integrated) has been changed. Yes, I have NGK, the right ones. The car runs OK when I reset adaptations but after some time it learns some weird fuel trims and the car drives badly, shakes in idle a lot.

[NiBe]

New data.

Idle in closed loop and in open loop. In closed loop my MAF readings are so low I totally don't understand why. MAF sensor is 2 days old.

As you can see from the closed loop screenshot it runs rich as hell (it is both idle).

The LTFT looks good because it has adaptations reset 50 km ago. After few another km they will be -10 in idle.

What is wrong?

[SvenHz]

Hmm well this info does not ring a bell with me but the cat temp is high, hence there is fuel being burned there. Your fuel rail pressure seems off; I am under the impression it should always be around 150.000 hPa (15000 kPa). If I were you I would do some diagnosis using INPA because it allows you to relate to the info that is on bimmerprofs. For instance, what are the actual lambda values (in 3 places: pre-cat, post-cat, NOx sensor)?

[NiBe]

Hello,

cat is hot because it is (both) in the middle of city drive, taken on traffic lights.

I replaced high pressure and low pressure sensors last week.

Pressure switches to 100 000 only in closed loop. Once in open loop it gets back to 150 000.

additional data:
On the left screenshot (open loop):
Sensor 1: 1.10mA
Sensor 2: 0.01V

On the right screenshot (closed loop):
Sesnor 1: 0mA (jumping between -0.1 up to 0.1 but mostly zero)
Sensor 2: 0.87V

Not sure if it is related but my time on dashboard reset this night, maybe some electrical issue causing this strange behavior?

[NiBe]

Hi, I used INPA. The image with zero volts after cat corresponds to the open loop idle and the other image corresponds to closed loop.

[SvenHz]

I don’t think “open loop” is the correct term for the idle in which the post cat lambda reads <0.1V; it corresponds to a lean mixture which could be correct (hot idle after driving, N43 should switch to stratified fuel mode, lambda value, not voltage, >2.0).
Perhaps try this https://bimmerprofs.com/use-test-module-lambda-probes/
There is some other info somewhere else on the site on proper resistance values of cold/hot probes. That should allow you to eliminate electrical/wiring issues of the probes.
Were the new injectors properly coded?

[NiBe]

I agree. Car Scanner app shows incorrect info. Open Loop = Stratified mode, Closed Loop = Homogeneous mode. Now it makes sense why the car is mostly in Open Loop (Stratified) and when WOT then it is in Closed Loop (Homogeneous).

Thanks for the link but the test is based on the fact that the engine has two banks (eg. N53) and mine (N43) has just one so this test is not available for my engine.

I have paid online diagnostics from Bimmerprofs so looking forward for their diagnostics results.

So: my engine idles OK in Stratified mode but notOK in Homogeneous mode.

[SvenHz]

Any updates?

[NiBe]

Investigation so far shows that in Stratified mode everything looks normally but in Homogeneous mode DME adds 15% of fuel to Cylinder 1 and removes 15% of fuel from Cylinder 2. Currently we are trying to find out why DME does that.

[NiBe]

So far no progress forward :/

[NiBe]

Bimmerprofs has gave up. So if someone has some idea I would love to hear it.

[F31B48]

Originally Posted by NiBe

Bimmerprofs has gave up. So if someone has some idea I would love to hear it.

What i-level is the DME running? Do you have access to ISTA?

[NiBe]

Originally Posted by EvaBmw

What i-level is the DME running? Do you have access to ISTA?

Hello I have ISTA/D

[F31B48]

Originally Posted by NiBe

Hello I have ISTA/D

Try running through the ISTA guided troubleshooting for each of the faults. It will tell you what to test and what readings you should expect.

[NiBe]

Found this when doin leak down test (results ok). Could this be the reason why dme is putting 15% more fuel to cylinder 1? It is coil on cylinder 1. Referring to the wire not to the disconnected coil.

[SvenHz]

Bimmerprofs gave up?!
Do you have access to an oscilloscope to view the ignition voltage coming from the DME? Measure it right before the coils. It would include that potentially broken cable (any signs of current leaks?).
At this point you could try putting (a) new coil(s) in… but honestly that is just guesswork from my end.

[rjahl]

Originally Posted by NiBe

Investigation so far shows that in Stratified mode everything looks normally but in Homogeneous mode DME adds 15% of fuel to Cylinder 1 and removes 15% of fuel from Cylinder 2. Currently we are trying to find out why DME does that.

Are you sure that is cylinder one and two and not Bank 1 and Bank 2? As far as I know the DME can only adjust fuel trims by the cylinder bank.

Also, who installed your new fuel injectors? Did the DME get the correct adaption values programmed for each? Index 11? Not new? Where they recon by someone from mysterious places?

[NiBe]

Originally Posted by rjahl

Are you sure that is cylinder one and two and not Bank 1 and Bank 2? As far as I know the DME can only adjust fuel trims by the cylinder bank.

Also, who installed your new fuel injectors? Did the DME get the correct adaption values programmed for each? Index 11? Not new? Where they recon by someone from mysterious places?

Yes, my car has only 1 bank, it is 4 cylinder with one pre cat and one post cat lambda.

The car does "cylinder efficiency test"
https://bimmerprofs.com/tests-chemical-efficiency/

And this test is causing that DME puts 15% more fuel to cylinder one and 15% less fuel to cylinder 2. From unknown reason.

Four new index 11 injectors installed and coded.

Here is idle after fast drive (150km/h in Homogeneous mode)

Around 1:34 you can see that adaptation on individual injectors goes from -16% up to +13%. It is too much.


Here is idle also when I reset adaptations and cruised slowly (100km/h) and thus in Stratified mode. This video looks OK, injector adaptations less than 1%.

Problem is that in Homogeneous mode the adaptations of injectors is far from being OK and it generates problems such as rough idle and misfires.

[NiBe]

I replaced all coils with Bosch. This is after first drive, around 10km. Long story short no change.