N62 - Misfire at Idle P0300, P0301 ect.
 

Hello Guys,

It's been a while since my last post here. My 2006 4.4l sport has been running like a champ until today.

I went for a drive and I pulled up to a light and I get a flashing CEL
and the idle starts to lope. I pull away with a loss in power so I pull to a parking lot, shut the engine off and plug in my Bluetooth scanner and get the torque app up on my phone.

I restart my X and the severe misfire I was experiencing before shut down is almost completely gone and seems to be idling fine. My CEL is still illuminated.

I scan the car and it was showing a P0300 like I knew it would for random cylinder misfire.
I then checked historic faults and see

P0301
2
4
5
6
8
So it logged misfires on all cylinders except 3 and 7

Then I clear codes with it running and instantly the idle goes back to normal and its running like I expect. I get on my way and its running fine. A mile or 2 later I pull up to a stop light and after 30 seconds at idle it starts to flash my CEL and misfire.

Hopefully that's not to much of a novel I like to be as specific as I can in how a symptom is manifesting itself.

Is this obvious for you fellow N62 members on where I should start with this one? I've fixed these symptoms with ignition coils and swapped out hoses and intake plastics on other BMWs in the past when vacuum leaks manifested themselves in a similar fashion.

Where would you start?

Thanks in advance guys!

sounds like air intake , and MAF sensor might need to be checked and reset ............

Since you have the App Torque see what the short term fuel trim and long term fuel trim for each bank is doing. Check the voltage for the 02 sensors 1 and 2 (pre cat and post cat) for both banks. You can also look at the air flow rate at the MAF, it will be g/s.

Idle related misfires are rarely coil/spark plug related.

Need to see Freeze Frame data and warm idle Fuel Trim values.

Might as well set up the Logging because this can be shared with someone like myself that can analyze and graph the data.

This is some older data I put together, not sure if the menus/layout has changed.

Start Torque Pro program on Droid device.

Touch the Droid Menu button.

Choose Settings in Torque Pro.

Choose Data Logging & Upload.

Select what to Log, choose only things you need to Log for faster logging.

Select File Logging Interval, start with 1 second unless you have only a few items to Log.

Select Log When Torque Is Started.

Select Only When OBD Connected.

Unselect Automatically Log GPS, this is a time and resource waster for OBD Logging.

Decide what you want to select for Rotate Log Files.

Select Format Log Files.

Enter User Email Address.

Test Settings

From Realtime Information page, select the Droid Menu, select Email Logs, select what "TrackLog" to email and it should be in the CSV format.

I usually recommend setting up a DropBox Free account and upload the .CSV files to DropBox and then paste the share URL link back in the thread so people can download and review the data.

Thanks for the replies guys!

I did some more scanning with torque this evening and looked for the stuff you mentioned. I'm using the free version, not pro but I was able to pop around in some menus and find a few things.

The most notable of which is Fuel/Air Status widget

It has 2 categories

Fuel system status And Secondary air status

With no CEL light illuminated and it running fine.

The Fuel system status category reads:
Closed loop system running or system reading form o2 sensors

and the Secondary air status just reads:
System not supported

Once it starts to idle funny throw a CEL light solid or flashing the

Fuel System Status category reads:
Open Loop due to system failure

So that got me thinking if when its running fine it says its receiving data from the o2 sensors. in that category and when it's misfiring that category says open loop system failure.

Then I toggled display on for O2 sensor voltage for bank 1 and 2, not sure if they were pre or post or what it was letting me read but I this is what I saw.

Running fine with a cleared ECU after fresh start it drives fine like I mentioned in my earlier post. The values on both banks raise and fail equally as I speed up and slow down. When I stop and it starts to idle I notice that bank 2 shoots all over the place and then the CEL illuminates and I get 0.0V from both banks.

Does this point to a possible o2 sensor issue?

Here are some screen shots

http://www.xoutpost.com/members/lexi...re2583-1-1.jpg
http://www.xoutpost.com/members/lexi...re2585-1-2.jpg
http://www.xoutpost.com/members/lexi...re2584-1-4.jpg

This is not likely an O2 sensor issue, trust me.

If you are only using Torque Free, move on from Torque Free and spend the $3.99 and buy OBDFusion, it is far better than Torque Pro as far as I am concerned.

I need to see Freeze Frame data Logged data will tell me WAY more than you can convey.

This problem is likely a Lean problem which will be clearly shown with the data.

Lean conditions are more often than not due to vacuum and/or crankcase air leaks. Occasionally a soft failing fuel pump could be an issue as well.

For vacuum or crankcase air leaks, smoke testing is the easiest way to figure out if and where a leak is.

Here some examples of ways to smoke test:

https://www.youtube.com/watch?v=AsgB9eBl58I

https://www.youtube.com/watch?v=PnU-SY6egr4

https://www.youtube.com/watch?v=zMok2y05jNE

The system was in closed loop, but it went to open loop

http://www.xoutpost.com/members/lexi...re2583-1-1.jpg

How can you say that it is not a 02 sensor issue? Since he has the app torque I would suggest the OP monitor the 02 sensor voltages for ALL of the Sensors.

The sensor that the OP posted is for the post cat 02 (B1S2) sensor, you need to post the 02 B1S1 and 02 B2S1 voltage readings as that is what is used by the DME to control the engine.

http://www.xoutpost.com/members/lexi...re2584-1-4.jpg

Short term fuel trim will tell you if the engine is running lean. If the fuel trims are in the plus range that mean the DME is commanding the system to add fuel. Fuel trim numbers will have to be over 10% for a lean condition.

I deal with this ALL the time, snap shot data from people that do not know what is required leads to miscues and unnecessary parts replacement.

The ONLY time I ever see O2 sensor faults that actually trigger codes is when the heater(s) fail in the sensors. I find that lazy O2 sensor rarely show up and are flagged by the DME/ECU.

Also I do not trust Torque, had too many problems with it and the App developer is non responsive.

Fuel System Status changes for many reason, to include deceleration with fuel cut off and I do not believe Torque actually reports accurately the 5 states for the Fuel System Status.

You also cannot analyze any data other than maybe engine temperature with a snap shot from the gauges.

Logs are REQUIRED to get the full picture and Logs cut down on easily 20+ posts in a thread back and forth trying to get the full picture and data from someone that barely understands how to use the App or has limited understanding of OBDII.

Even if the OP posts the Pre-cat O2 sensor Voltages from a single snap shot, this means NOTHING. Logging is the only way to see everything that is going on. Additionally Freeze Frame data is very helpful to understand under what conditions any codes were stored.

I fully understand Fuel Trim values and often find that there are problems when in fact there is no SES/CEL/MIL. Again, Logs when set up properly will show the entire picture. Just because the SES/CEL/MIL is not on does not mean there are no problems.

Data is key analyzing any driveability problem and will either rule in or out specific problems or subsystems.

BTW, 3.5 g/s MAF reading at idle seems a bit low for a 4.4l V8.

SMOKE Tester DIY. Let me know if you guys can't see pics.

How to: Build an emission smoke leak detector - The Garage Journal Board

Quicker and cheaper - https://www.youtube.com/watch?v=AsgB9eBl58I

Pump is a cheap fluid transfer pump that most auto parts store have, a rubber glove and a cheap cigar!