[Thomachaan]

I recently brought my car back from death after botching the valve cover job A few hundred miles later I'm left with this issue, hope y'all can share your experience. My first guess: PCV diaphragm.

Generic Codes:
P0175 System too rich bank 2
P0172 System too rich bank 1
P1105 Manifold differential pressure

BMW Codes per ISTA+:
2D29 DME: Differential-pressure sensor, intake manifold: plausibility
29E1 DME: Mixture control 2
29E0 DME: Mixture control

Symptoms:
->When fully warmed up, idle hunts slightly, I hear and feel it. Very slightly rough.
->There is good suction when opening oil cap while running (no whistling, nothing crazy).
->Gear shifts at low speed are either sluggish or jerky. When throttle is 1-25%, it takes about 2-3 seconds for power to build to what I'm used to, then it zooms onwards. Highway is fine, harder throttle seems fine too.

The car is a 2009 328i xDrive (N51). I've reset adaptations for valvetronics and transmission. Oil is @ ~8k miles, oil pan gasket is seeping/leaking, CCV heater was unclogged recently, PCV diaphragm was replaced with an eBay special, passages in valve cover were cleared out with brake cleaner, breather hoses are good, and no vacuum leaks along intake (used a smoke machine).

Anyone have advice on where to start diagnosing? I'll update with the progress, and will absolutely have this problem fixed one way or another.

[Hoody007]

Originally Posted by Thomachaan

I recently brought my car back from death after botching the valve cover job A few hundred miles later I'm left with this issue, hope y'all can share your experience. My first guess: PCV diaphragm.

Generic Codes:
P0175 System too rich bank 2
P0172 System too rich bank 1
P1105 Manifold differential pressure

BMW Codes per ISTA+:
2D29 DME: Differential-pressure sensor, intake manifold: plausibility
29E1 DME: Mixture control 2
29E0 DME: Mixture control

Symptoms:
->When fully warmed up, idle hunts slightly, I hear and feel it. Very slightly rough.
->There is good suction when opening oil cap while running (no whistling, nothing crazy).
->Gear shifts at low speed are either sluggish or jerky. When throttle is 1-25%, it takes about 2-3 seconds for power to build to what I'm used to, then it zooms onwards. Highway is fine, harder throttle seems fine too.

The car is a 2009 328i xDrive (N51). I've reset adaptations for valvetronics and transmission. Oil is @ ~8k miles, oil pan gasket is seeping/leaking, CCV heater was unclogged recently, PCV diaphragm was replaced with an eBay special, passages in valve cover were cleared out with brake cleaner, breather hoses are good, and no vacuum leaks along intake (used a smoke machine).

Anyone have advice on where to start diagnosing? I'll update with the progress, and will absolutely have this problem fixed one way or another.

You have a 15 year/150K warranty as it’s an N51. Why not let the dealer fix it for free?

[dpaul]

Since your troubles started after valve cover and PCV valve replacement, it stands to reason that those are where your problems lie. PCV problems can lead to either rich or lean conditions but you report "normal" crankcase vacuum so maybe PCV is OK. Might be worth actually measuring pressure/vacuum. Shouldn't be much at idle, ~30 mbar (-0.015 psi)

A simple and relevant diagnostic is to assess MAF output values in real time. If out of normal range, I'd check the connector, then assess continuity of the wiring between MAF and DME. If they are okay, replace the MAF. I'd use INPA to read MAF but assume ISTA has this function buried in it somewhere.

EDIT: Hoody007 has a good point!

[Thomachaan]

Hoody007 ha I wish, but I'm at 179k miles so no hope for SULEV warranty.

Originally Posted by dpaul

Since your troubles started after valve cover and PCV valve replacement, it stands to reason that those are where your problems lie. PCV problems can lead to either rich or lean conditions but you report "normal" crankcase vacuum so maybe PCV is OK. Might be worth actually measuring pressure/vacuum. Shouldn't be much at idle, ~30 mbar (-0.015 psi)

A simple and relevant diagnostic is to assess MAF output values in real time. If out of normal range, I'd check the connector, then assess continuity of the wiring between MAF and DME. If they are okay, replace the MAF. I'd use INPA to read MAF but assume ISTA has this function buried in it somewhere.

EDIT: Hoody007 has a good point!

Idk if the crankcase vacuum is normal, cuz it does have some force, but not ridiculous force.

So I checked to see if my PCV could hold vacuum while the engine was off. The vacuum pump from my HF bleeder kit broke, so, I tested by taking the thin tube off the intake that goes to the PCV, sucking on that end, and sticking my tongue in to block and hold suction. Seemed to hold vacuum for like a minute, cuz it had the same force and sound as when I immediately let my tongue off. Patent pending, traditional test coming later.

I'm gonna clear the codes and take it for a nice drive, see what happens. I just got rid of a clicking sound today that happened whenever I braked, louder with more pressure and speed. It mighta been the hanging front left brake sensor wire I rerouted, or coulda been the rust I removed between that wheel and its rotor. Progress

[Thomachaan]

Quick question to the forum: Where/how can I monitor running values for the manifold's differential pressure sensor and the MAF? INPA? ISTA?

Update: Past few days I've been driving the car as much as I can, a few hours each time. Not much change in performance, but here are some more descriptions.

~New code: P00BD : Mass or Volume Air Flow 'A'. Circuit Range/Performance - Air Flow Too High.
~Engine lightly stumbles when coming to a stop or idling.
~Stumbles on wide open throttle. It'll rev high but with random glitches here and there.

Now I'm unsure if either the MAF is faulty, the differential pressure sensor is faulty, or there's something clogging the intake like a rag \_'- '_/

[dpaul]

Originally Posted by Thomachaan

Quick question to the forum: Where/how can I monitor running values for the manifold's differential pressure sensor and the MAF? INPA? ISTA?

Update: Past few days I've been driving the car as much as I can, a few hours each time. Not much change in performance, but here are some more descriptions.

~New code: P00BD : Mass or Volume Air Flow 'A'. Circuit Range/Performance - Air Flow Too High.
~Engine lightly stumbles when coming to a stop or idling.
~Stumbles on wide open throttle. It'll rev high but with random glitches here and there.

Now I'm unsure if either the MAF is faulty, the differential pressure sensor is faulty, or there's something clogging the intake like a rag \_'- '_/

In INPA:
Model series -> Engine -> Engine Type (select N52k MSV80) -> Live Data -> Analog measurevalueblocks -> Raw data -> HFM Sensor airmasse (MAF)

Not sure where differential pressure values are, just look around in MWB 1,3,6. I know there is an ambient pressure readout (umgebundsdruck) - not sure how that relates to differential pressure.

IN ISTA:
Operations->Read Out Vehicle Data -> Control unit Tree -> Select DME -> Select Call Up ECU functions -> Diagnosis Scan. Then look around

[Thomachaan]

What I really need to know is, how do I diagnose if this is my MAF, DPS, O2 sensors, or a combination failing?

Hey @dpaul, thanks! Found everything in ISTA, but not sure what I'm looking for. My INPA's MSV80 menus are in German but found them.

Tried driving with MAF unplugged and the car seemed to idle better w/o hunting, better initial throttle response & shifting too. At high throttle, the engine flailed and throttle response was nearly gone and stayed gone till restart, like limp mode + stumbling but no dash indication.

[dpaul]

Originally Posted by Thomachaan

What I really need to know is, how do I diagnose if this is my MAF, DPS, O2 sensors, or a combination failing?

Hey @dpaul, thanks! Found everything in ISTA, but not sure what I'm looking for. My INPA's MSV80 menus are in German but found them.

Tried driving with MAF unplugged and the car seemed to idle better w/o hunting, better initial throttle response & shifting too. At high throttle, the engine flailed and throttle response was nearly gone and stayed gone till restart, like limp mode + stumbling but no dash indication.

In INPA if you found HFM airmasse sensor or Luftmasse, there should be a a range of values next to the bar representation of the actual values. There should also be an exclamation point next to the indicator. if the value is outside the normal range. If the air flow sensor values are abnormal, it is likely that either the sensor, its connector or the wires to the DME are at fault. Etc.

If you post pictures of status (F5) ->analog (F2) ->raw data (F5) and MWB1 (F1) and MWB3 ((F3) I can try to interpret them for you. Also post status (F5) -> exhaust gas (F6) and rough running (F7)

[Scuzone]

I just kicked 0175 & 0172 after replacing CCV & Starter, turned out the Indy left off the air scoops before the intake on my e46. I’d check there 1st as I see on my e91 they are starting to crack and shred. So look before the air box on the intake. As for the diff pressure I can’t help but maybe wrong fluid or two much good luck

[dpaul]

Originally Posted by Scuzone

I just kicked 0175 & 0172 after replacing CCV & Starter, turned out the Indy left off the air scoops before the intake on my e46. I’d check there 1st as I see on my e91 they are starting to crack and shred. So look before the air box on the intake. As for the diff pressure I can’t help but maybe wrong fluid or two much good luck

Hard to understand how air scoops would make a difference to AFR

[gbalthrop]

Originally Posted by Thomachaan

I recently brought my car back from death after botching the valve cover job A few hundred miles later I'm left with this issue... Generic Codes:
P0175 System too rich bank 2
P0172 System too rich bank 1
P1105 Manifold differential pressure

TWO rules for Diagnostics (there are MORE, but these two MAY apply here ;-):
1) If Fault occurs after repair done, look for something affected by repair. Here the Intake Manifold Pressure Sensor Connector/ Wiring.
2) If you have two Fault Codes reporting a "Condition" (here BOTH Banks 1 & 2 TOO Rich), and ONE Fault Code reporting a Sensor Signal Fault (here P1105 = "Intake Manifold Pressure Sensor, Plausibility"), Test that component, its connector & wiring.

So I don't know about you, but I'd take a look at INPA > F5 Status > F2 Analog > F2 OBD II Measured Values: "Saugrohrdruck" = Manifold Pressure. That value should be "0 kPa" (Zero kilopascals) with ignition ON, Engine OFF. The value should be ~ 4 kPa (~ .5 PSI, 1 inch Mercury, or .04 Bar with Engine ON, at idle (either cold or warm idle). The value should change slightly, by one or two kPa, when you quickly "blip" or press/release the Accelerator Pedal. I assume that is actually a slight "Vacuum" or "differential pressure" LOWER than Ambient Atmosphere pressure. ANY pressure reading is "differential" or as compared to something else.

If you have NO change in "Saugrohrdruck"/ Manifold Pressure Sensor Signal as received by DME, between Engine OFF, and Engine Idling, check your connector & wiring.

ISTA wiring diagram, with Location, and INPA screens showing "Saugrohrdruck"/ Manifold Pressure Sensor Signal at cold idle vs. engine OFF are attached to next post.

Please let us know what you find,
George

[gbalthrop]

As described in prior post, attached are following related to 328xi (3/2007):

1) ISTA SSP wiring diagram showing Location & Wiring of B6239 Intake Manifold Pressure Sensor;

2) INPA ScreenPrints showing INPA > DME (MSV80) > F5 Status > F2 Analog > F2 OBD II Measured Values

a) Saugrohrdruck = Manifold Pressure (4 kPa) with Engine at cold idle, immediately after engine start

b) Saugrohrdruck (0 kPa): Engine OFF, Ignition ON.

George