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Old 07-14-2017, 10:54 AM   #1
tomandhisjones
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P0171 & p0175

Hey guys, looking for some insight, as I am completely stumped. I recently purchased my second E46 M3, after having a 335i for a while, and have had more trouble with it than I had hoped.

When I purchased, it had a rough idle, so I pulled the codes, which were P0171 and P0174 (running lean on bank 1 and 2). Everything pointed to either a bad MAF sensor, or a vacuum leak. Changed the MAF sensor, and the codes changed to P0171 and P0175 (lean bank 1, rich bank 2). Went and had a smoke test done, and there wasn't any vacuum leaks found.

I went ahead and changed the pre-cat 02 sensors, and that still didn't solve the issue.

I started to think that maybe it was a fuel delivery issue, so I first replaced the fuel filter, and then the fuel pump. I gained a lot of power back after the fuel pump change, which is great, and the idle isn't as rough, but still noticeable. It's still throwing the same codes P0171 and P0175.

Took it to a stealership, and had them diagnose for the low low price of $200, and they suggested that my cats were clogged, and wanted to replace them for $5k (ok...). I had a local shop go ahead and "clean out" my cats, and that didn't resolve anything, except for freeing up some horsepower.

I've hooked it up to a peake reader, and received the codes hex 90 and hex 91 or dec 144 and 145.

I'm at a complete loss, and would appreciate any insight anyone has.

Last edited by tomandhisjones; 07-14-2017 at 10:54 AM.
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Old 07-14-2017, 11:00 AM   #2
All2kool
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That is a head scratcher.

Last edited by All2kool; 07-14-2017 at 11:02 AM.
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Old 07-14-2017, 11:04 AM   #3
jfoj
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Get rid of the Peake Reader, it is boat anchor.

You need Freeze Frame and Fuel Trim data to understand more about what is going on. If you have the original MAF you removed, hang on to it.

Spend under $30 for the OBDFusion App and the proper interface for your phone/tablet platform.

Android - https://www.amazon.com/Veepeak-Scann...eywords=veepea

Iproducts - https://www.amazon.com/Veepeak-Scann...eywords=veepea

See my comments in this thread - http://forum.e46fanatics.com/showthread.php?t=1050205

Where did you purchase the replacement MAF and how much did you pay for it?

Also understand that Pxxxx codes are FAR more accurate than BMW specific codes when it comes to driveability problems.

For example, at least based on the Bentley Manual here is what the BMW Fault Codes 144 and 145 translate to, not there are MULTIPLE translations and they do not agree for each code:

144 Translation
P0170 - Fuel Trim (Bank 1)
P0171 - System Too Lean (Bank 1)
P0172 - System Too Rich (Bank 1)

145 Translation
P0173 - Fuel Trim (Ban 2)
P0174 - System Too Lean (Bank 2)
P0175 - System too Rich (Bank 2)

It is really hard for a modern vehicle to actually run Rich without false or bad sensor data being sent to the DME. Almost ALL problems tend to be Lean conditions.
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Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 07-14-2017 at 11:12 AM.
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Old 07-14-2017, 11:46 AM   #4
tomandhisjones
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Thanks jfoj.

I have both a bmw specific reader, INPA, and a regular OBDII reader. The specific reader and INPA both showed codes 90 and 91. OBDII specific showed p0171 and P0175.

I purchased the MAF sensor from NAPA for $115 or so. I actually returned the first one, and got a second one, just to make sure the new MAF sensor wasn't part of the problem. I still have the old MAF, and when I plug it back in, the code changes from P0175 to P0174 (both lean).

I was doing some more research, and remembered that one of the o2 sensor wires had gotten shorted out on the cat, and had to be fixed by my mechanic. I was reading that it may have blown a fuse, so I am going to pop open my e-box when I get home, and make sure all of the fuses are intact.
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Old 07-14-2017, 12:03 PM   #5
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A few things:

1. What OBDII tool do you have? Does it support Freeze Frame and Live data?
2. You DO NOT buy a MAF at your local auto parts store and you do not buy a MAF that is usually under $200. You are just throwing your money away.
3. I doubt there is a fuse problem due to the O2 sensor wiring, but you can check it.
4. If the O2 sensor wiring was spliced, it is possible to connect the O2 sensor wires backwards. The O2 sensor wires are polarity specific and if they are connected backwards it will drive the DME crazy.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-14-2017, 12:15 PM   #6
tomandhisjones
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1. It's one bought of Amazon. Here is an album of live data I pulled before replacing the fuel pump http://imgur.com/a/zuRB0
2. It's a Bosch MAF sensor I purchased, which I thought was OEM. Where should I pick one up at?
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Old 07-14-2017, 12:39 PM   #7
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The link you provided is not a generic or standard OBDII tool, it is a stand along BMW specific tool and it is not what need here. You NEED to buy the OBDFusion App and interface, it will run circles around EVERYTHING you currently have. Trust me.

As for the MAF, Siemens/VDO or possibly Bosch should have been the OE sensor.
One of the big problems is there are MANY counterfeit parts, especially MAF's on the market, they have great labels, good boxes and logos and part numbers cast into the plastic housing.

It appears that the M3 MAF can be removed from the housing, been a long time since I have been hands on with a M3.

I find that OEMBimmerParts is a reliable supplier and seems to have know quality parts. You might wait to jump on a different MAF, but I NEVER buy MAF's from the local parts store. Some of them are often rebuilt or re-manufactured, not sure how this works when I want a NEW unit.

https://www.oembimmerparts.com/BMW-M...27839014m3.htm
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-14-2017, 12:45 PM   #8
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Quote:
Originally Posted by tomandhisjones View Post
Hey guys, looking for some insight, as I am completely stumped. I recently purchased my second E46 M3, after having a 335i for a while, and have had more trouble with it than I had hoped.

When I purchased, it had a rough idle, so I pulled the codes, which were P0171 and P0174 (running lean on bank 1 and 2). Everything pointed to either a bad MAF sensor, or a vacuum leak. Changed the MAF sensor, and the codes changed to P0171 and P0175 (lean bank 1, rich bank 2). Went and had a smoke test done, and there wasn't any vacuum leaks found.

I went ahead and changed the pre-cat 02 sensors, and that still didn't solve the issue.

I started to think that maybe it was a fuel delivery issue, so I first replaced the fuel filter, and then the fuel pump. I gained a lot of power back after the fuel pump change, which is great, and the idle isn't as rough, but still noticeable. It's still throwing the same codes P0171 and P0175.

Took it to a stealership, and had them diagnose for the low low price of $200, and they suggested that my cats were clogged, and wanted to replace them for $5k (ok...). I had a local shop go ahead and "clean out" my cats, and that didn't resolve anything, except for freeing up some horsepower.

I've hooked it up to a peake reader, and received the codes hex 90 and hex 91 or dec 144 and 145.

I'm at a complete loss, and would appreciate any insight anyone has.


The dealership is reading lean and rich, and blaming it on the CATs?! That should be a death penalty offense.
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Old 07-14-2017, 09:07 PM   #9
tomandhisjones
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Went ahead and bought OBD Fusion, as I already had a wifi OBDII adapter, and pulled a live feed for about 20 minutes. Honestly, not sure what I am looking for, but here is a live data log if anyone is interested.

https://www.dropbox.com/s/nxbw0g07pd...84233.csv?dl=0

Last edited by tomandhisjones; 07-14-2017 at 09:07 PM.
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Old 07-14-2017, 09:20 PM   #10
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Read the PDF in this thread, it is geared toward Android, but you only need about 20 PID's to monitor.

http://forum.e46fanatics.com/showthread.php?t=1097893

I would prefer a 4 min warm idle Log when you get a chance and a Diagnostic Report while the engine is idling, ignore the Pop Up warning.

I will try to see if there are any clues in what you captured so far.

My initial feeling is the O2 sensors may be connected wrong, something to rule out before you through too many parts at the car.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 07-14-2017 at 09:27 PM.
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Old 07-15-2017, 01:11 PM   #11
tomandhisjones
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Ok, got the diag and warm idle data. Thanks again for all your help.

Idle data
https://www.dropbox.com/s/k8vfmz1dq6...24755.csv?dl=0

Diag
https://www.dropbox.com/s/2kyek15fnd...7-15.html?dl=0
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Old 07-15-2017, 08:35 PM   #12
jfoj
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I think this car may be really screwed up, but should be pretty simple to resolve.

Looking at the Diagnostic Report, it shows that the Distance traveled while MIL is activated as 40721 miles!! If this is anywhere near to correct, this car has had problems for a LONG time.

So a few initial comments.

1. The MAF is OVER REPORTING! This is hard to do, not sure what MAF is installed, likely it may be a counterfeit MAF. These engines should read about 4.2 g/s at idle, yours is over 7 g/s!! Even if you reinstall the original MAF and it triggers Lean codes, do not worry about this as long as the MAF values is around 4 g/s at idle.

2. I have a feeling the O2 Sensors are connected wrong and/or may have possibly had wiring repairs or replaced with Universal sensor(s)?

You need to trace and label easy O2 sensor at the connector end. Label them for the Sensor and Bank number. Pre-cat O2 sensors, the ones right under the hood should be Sensors #1. The lower O2 sensors behind the catalytic converters are Sensors #2. Bank # is cylinder 1-3 and Bank #2 is cylinder 4-6.

So you should label the sensors as Bank #, Sensor #. Example 1-1 would be Bank #1, Sensor #1 (Pre-cat).

Then you need set up a dashboard on OBDFusion and make a Digital Gauge for each O2 Sensor. You will then need to unplug one sensor at a time and find out what sensor quits responding. Then you need to see sensor label matches the gauge label.

I also would like to see a 2 minute Log with the engine not running, just turn the ignition on and connect OBDFusion and allow the Log to run, I need to see the baseline Voltage for the O2 sensors.

Again, probably a simple problem of sensors connected wrong and a really bad MAF that over reports. Most MAF's under report when they degrade and age, most over reporting MAF's are either the wrong part or a counterfeit.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-16-2017, 10:07 AM   #13
tomandhisjones
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Here is the link for the two minute log with the engine off.

https://www.dropbox.com/s/x4jej55tjr...95918.csv?dl=0

I plugged the old MAF back in, and it was hanging around 9.5 g/s, so I'm not sure that changed anything for the better
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Old 07-16-2017, 11:21 AM   #14
tomandhisjones
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When labeling and checking the o2 sensors, do I need to do this with the car running, or just with the ignition on?
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Old 07-16-2017, 12:29 PM   #15
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Quote:
Originally Posted by tomandhisjones View Post
Here is the link for the two minute log with the engine off.

https://www.dropbox.com/s/x4jej55tjr...95918.csv?dl=0

I plugged the old MAF back in, and it was hanging around 9.5 g/s, so I'm not sure that changed anything for the better
So the Log is helpful, it shows that the baseline Voltage is 0.45 Volt for each O2 sensor, so this being said I do not expect a DME problem or shorted/grounded wiring.

Make sure the MAF terminals are tight, you may need to pinch then closed a bit. You might want to watch the MAF value while the engine is idling and then wiggle/move the wiring and see if the MAF value changes by a large amount.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 07-16-2017 at 12:31 PM.
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Old 07-16-2017, 12:32 PM   #16
jfoj
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Originally Posted by tomandhisjones View Post
When labeling and checking the o2 sensors, do I need to do this with the car running, or just with the ignition on?
After the labeling has been done, it is best to disconnect 1 sensor at a time either with the engine running or disconnect a sensor then start the engine and run a Log for at least 1 minute if you are not sure what we are looking for.

Make sure if you run a Log you can note what sensor was disconnected.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-16-2017, 01:44 PM   #17
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Originally Posted by jfoj View Post
It appears that the M3 MAF can be removed from the housing, been a long time since I have been hands on with a M3.

I find that OEMBimmerParts is a reliable supplier and seems to have know quality parts. You might wait to jump on a different MAF, but I NEVER buy MAF's from the local parts store. Some of them are often rebuilt or re-manufactured, not sure how this works when I want a NEW unit.

https://www.oembimmerparts.com/BMW-M...27839014m3.htm
The MAF is one of the few cheaper parts on an M3 vs. non-M E46. It sounds like you got the correct one from Napa. I would have bought this OE Bosch one from fcpeuro.com with their lifetime warranty and only $80.
https://www.fcpeuro.com/products/bmw...-m6-0280218062
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Old 07-16-2017, 09:29 PM   #18
tomandhisjones
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Ok, so finally got around to pulling the plugs and running logs (long day with the kiddos). My pres and my posts both sit together, so I used the following diagram to pull in a certain sequence. Sorry upfront that it's kind of a wonky order.



My sequence went:

Post Cat #2
https://www.dropbox.com/s/deu8ljl6jn...04707.csv?dl=0

Post Cat #1
https://www.dropbox.com/s/j3nyabinxm...04905.csv?dl=0

Pre Cat #1
https://www.dropbox.com/s/d47y5ys3sy...05132.csv?dl=0

Pre Cat #2
https://www.dropbox.com/s/capsbjiutm...05531.csv?dl=0

One thing I did notice, was that pre cat #2 had a long length of wire without thermal wrapping (6+ inches). Makes me wonder...
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Old 07-16-2017, 10:39 PM   #19
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So if your drawings are accurate and correct and your comments on the Logs are accurate and correct.

BOTH the Pre-cat and Post-cat sensor connections are swapped Bank to Bank.

Just swap the Pre-cat connections and run another Warm Idle Log when you get a chance.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-16-2017, 10:57 PM   #20
tomandhisjones
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Thanks again jfoj. Only problem is, the each bank sensor has a specific plug design. I tried to swap the pres, and they wouldn't fit. If I try to swap them on the manifold, will they switch out ok?

Either that, or I could chop the wires, and resolder them.

Last edited by tomandhisjones; 07-16-2017 at 10:57 PM.
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