[GoDores]

I have a number of issues that I think are probably related to air or fuel control at low/idle RPM. Occasionally (maybe once a day or less) the engine will stall when I put the clutch in to come to a stop. The idle also sometimes "hunts" from about 500-900 RPM while in neutral at a stop. I also noticed that if I apply full throttle at low RPM the revs will bounce up in steps until I get to about 2000RPM, rather than smoothly increasing. None of these things happens all the time and I haven't been able to predict when they will or won't occur.

No check engine light. The attached pictures are the only codes that come up in a scan that seem like they might be related. Any ideas what might be causing these issues?

[gbalthrop]

Since 5 of the 6 Codes you list are related to the ESS (Eccentric Shaft Sensor), I would just take a SWAG and say maybe some further testing or examination of that component is warranted.

The ESS failure mode most commonly reported is where the Sensor develops an internal fault/ crack where oil gets into the sensor and affects electrical performance of the sensor (signal to the DME). It is usually manifested by oil seeping from the pins at the ESS Connector on the front-right of the Valve Cover. I have NOT personally had that issue, but I would think your performance issues are consistent with intermittent "slow" or "erratic" change of position signal to the DME from the ESS when Shaft Position changes.

Here is a TIS Procedure related to ESS "Gasket". A leaking external Gasket does NOT affect ESS function, so this page is linked ONLY to make sure you understand what to check. The oil seepage would be visible INSIDE the perimeter of the sensor (at Pins/Sockets), and any Gasket or perimeter leakage should NOT affect function unless it is getting into the Connector. If you find oil in the pins/ sockets at the connector, try cleaning thoroughly, with electronic contact cleaner, and seeing if that gives temporary improvement of symptoms:
https://www.newtis.info/tisv2/a/en/e...lid/1VnYDt5VKK

The Gasket can be changed WITHOUT removing the Valve Cover, but replacing the ESS requires VC removal.

I understand you have NOT associated the performance issues with a particular variable, but the performance faults do NOT occur for several minutes after cold start (oil viscosity high), and usually occur after running for 10 to 15 minutes, except for "hot-startup" (hot oil thinner), then the ESS failure mode described is MORE likely.

Eccentric Shaft Position, per ESS signal to DME, can be read using Activation in INPA or ISTA, but with an intermittent fault, particularly one that occurs more often when engine fully-warmed, it may NOT be easy to observe or confirm. I would suggest recording any Freeze Frame Data your Scan Tool can provide, along with the faults you have displayed here, and checking to see at what engine conditions (Temp, Load, etc.) any faults occur. INPA or ISTA might provide more specific definitions of the VVT faults.

The 2A1A fault is probably related to the purge valve flap NOT opening or closing when it should, and probably has NO relationship to the performance issues described. I would suggest same approach for that fault -- check FF Data & CLEAR. Scan again in day or two.

Please let us know what you find,
George

[nsjames]

mirrors the symptoms I had when my ESS was failing, but mine didn't even set a code.

don't buy aftermarket.
do all the valvecover gasket stuff while you're there.

[GoDores]

Thanks for the detailed response! I pulled the connector off and there was some oil inside the connector, although not a lot. I cleaned and dried both sides of the connector and cleared the codes. May not have a chance to drive it again until Monday but I’ll see what happens the next time I do. I’ll also see if I can monitor the code reader while driving to get some data. I have an old laptop with INPA on it but no way to power it while driving.

I assume this is the sensor: https://www.ecstuning.com/BMW-E91-32...rical/Sensors/
If I do replace it, is there really an advantage to the $450 OEM version over the $200 VDO version or the $300 version that says it’s upgraded to prevent oil damage?

[GoDores]

I drove the car again today with my scanner plugged in and two of the codes for the eccentric shaft sensor came back right away. I also looked at the data stream and the commanded position didn’t match the detected position. No stalling today but it doesn’t always do that. Don’t know why this didn’t trigger a CEL but oh well. I ordered the sensor and will update when I get a chance to install it.

[nsjames]

oil in the connector is a dead giveaway it's failed.

once the oil gets inside it, it's done. it contaminates the little wipers.
your symptoms and the oil are exactly what happened to mine.

I replaced mine with the VDO one from FCP. It was like $250.
It's been good for 10k+ miles so far. the original made it like 130, so I'm not too worried about ever doing it again.

[kissdaring]

I just posted about this. my car actually stalled once on a really hot day same symptoms and similar codes. looked at the eccentric shaft sensor and my seal was leaking the connector had a bit of oil not to much. used some contact cleaner on both ends cleared the codes nothing yet. I'm not sure if you have tired this.

also from my understanding the eccentric shaft sensor for some strange reason does not throw a engine light.

[NCSUPack24]

Originally Posted by nsjames

oil in the connector is a dead giveaway it's failed.

once the oil gets inside it, it's done. it contaminates the little wipers.
your symptoms and the oil are exactly what happened to mine.

I replaced mine with the VDO one from FCP. It was like $250.
It's been good for 10k+ miles so far. the original made it like 130, so I'm not too worried about ever doing it again.

x2 for the VDO. I replaced it pre-emptively while I was doing the valve cover (and gasket for the second time). Just really didn’t want to do that job again.

That install was 40k ago and I’ve had no issues.

[gbalthrop]

Originally Posted by GoDores

I drove the car again today with my scanner plugged in and two of the codes for the eccentric shaft sensor came back right away. I also looked at the data stream and the commanded position didn’t match the detected position.

224 degrees Eccentric Shaft "Actual" (Aktuell in German means "Current") position is JUUUST a little bit IMPLAUSIBLE since the shaft only rotates 180 degrees (from 0 to 180).

I seem to recall seeing something in TIS, Bentley or BMW TM stating that there are TWO Eccentric Shaft Angle sensor signals from the ESS to the DME, so that the DME can compare the two for plausibility purposes. IIRC, the two were mirror images so total was ALWAYS supposed to be 180 degrees?

ANYONE know of a reference source for that? -- I can't find it anywhere at the moment. It would seem to be supported by the TIS circuit diagram below, which shows two different Data Signals (T_DAT1S & T_DAT2S), Yellow & White wires, respectively. This circuit is for my 3/2007 328xi E91, which is ALSO Ti Ag, so since you don't give your model year -- hey if they're BOTH Ti Ag, it's GOTTA be the right circuit
https://www.newtis.info/tisv2/a/en/e...sensor/x3FAxcV

Seems to be little doubt that the ESS has garbled output signal issues, but if you want to just test the capability of your C110+ Scan Tool, you can always just turn Ignition ON, Engine OFF, and see what kind of Live Data (Parameters) it gives you at different Accelerator Pedal positions.

Unless you had already cleaned the ESS pins BEFORE you took the photos, I must say all I noticed was DIRT and NO Oil in the photos. If you did NOT clean the pins & Connector Sockets thoroughly, I would take the time to do that BEFORE going to all the trouble to replace the ESS. Pay particular attention to the Sockets for Pins #1 & #9, which are the signal wires, to make sure they are NOT damaged or pushed into the connector.

George

[GoDores]

Thanks for the update. I did order the VDO version. I have to think that's OEM and better than the Chinese ones on eBay.

My car is a 10/07 build 2008 model. I may check the data at different throttle positions, although with drive-by-wire I wouldn't think the computer would care about the pedal position with the car off.

There definitely was oil in the connector before I cleaned it. You can see a drop at the bottom of the housing in the second picture and a nice coat around the connector. I haven't had a stalling issue since then but the idle still bounces around sometimes. In any case, I'm going to replace the sensor so we'll see what happens.

[nsjames]

Originally Posted by GoDores

Thanks for the update. I did order the VDO version. I have to think that's OEM and better than the Chinese ones on eBay.

My car is a 10/07 build 2008 model. I may check the data at different throttle positions, although with drive-by-wire I wouldn't think the computer would care about the pedal position with the car off.

There definitely was oil in the connector before I cleaned it. You can see a drop at the bottom of the housing in the second picture and a nice coat around the connector. I haven't had a stalling issue since then but the idle still bounces around sometimes. In any case, I'm going to replace the sensor so we'll see what happens.

your car was built within weeks of mine.

if you unplug the ESS the DME will open the valves all the way and default to the throttle body.
in case it simply quits running.

[GoDores]

I finally finished replacing the sensor, and did the VANOS solenoids and spark plugs while I was in there. Cleared the codes and they didn't come back, but now I have an intermittent stumbling idle that feels like a cylinder is missing. No codes, but I'm guessing one of my ignition coils decided to retire after the removal/replacement. Ordered a new set of Bosch coils for Sunday delivery and hopefully everything will be in good shape after that.

[GoDores]

New coils seem to have done the trick. Idle is around 800rpm on startup and there's a little vibration, but after a minute it drops to 600rpm and is totally smooth. No codes from the DME and the live data over INPA shows all the various sensor measurements in the green.