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-   -   "Pending" P030X codes, occasional engine misfire (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/101938-pending-p030x-codes-occasional-engine-misfire.html)

Rookie48 10-07-2015 12:39 PM

"Pending" P030X codes, occasional engine misfire
Hello all... appreciate any thoughts on this issue. I scanned Google with no specific results.

2003 E53 3.0i MT 100k miles

At highway speeds (runs fine at idle and below highway speeds) my X5 started with an "occasional" misfire situation. While cruising along at 75-80 MPH, typically at partial throttle as in coasting down a hill for 15-20 seconds, the SES lights goes on, stays lit (not blinking), and the engine runs as if it is down one cylinder. It will continue running rough as on 5 cylinders for up to 5 minutes, then start running fine again, and the SES light will go out! I stop and pull codes - NO CODES! After a few more daily drives without issue, I get to work today and checked codes again (just keep seeing if something gets thrown) and find codes P0301 through P0306 are all in a PENDING state. The X5 did not stumble or drop to 5 cylinders as in the past, but I was in traffic and it could have happened while I was decelerating. No SES light at all.

This issue started last weekend when driving through some serious rain and roadway ponding, possibly getting some engine electrical component wet. The truck as has been driven at full operating temp, and in a garage with a dehumidifier, and the weather has been nice and dry since.

Since the issue resurfaces occasionally, I'm at a loss as to what it might be. At first I thought coils, but now I'm thinking fuel pump (although I would assume that would be an issue more under engine load than partial throttle).

Anyone else every had this issue and diagnosed it correctly? :dunno:

Ricky Bobby 10-07-2015 01:05 PM

Reset the throttle body adaptations, if you haven't changed your spark plugs I would do so preventatively since your mileage around 100k is fine to do so.

I had a random stumble one morning in the spring, it ran like crap until I shut it off and restarted, has run fine ever since. Have you run a bunch of fuel system cleaner lately?

Rookie48 10-07-2015 01:21 PM

Thanks trader4, Ricky Bobby:

The scanner is a PWOW ELM327 wifi unit with the OBD Fusion app on an iPad.

Spark plugs were changed 20K miles ago. I had run SeaFoam through about 5k miles ago, and my indie shop ran BG K44 through about 3k miles ago. The X5 seemed to run slightly better when the additive was in the tank...

Instructions to reset the throttle body adaptations?

UPDATE: Found this --> With the car off, turn the ignition to the on position(posit. 2) for 10 seconds(do not start) then turn the ignition off for 10 seconds. Then start the car.

Also - can the ELM327 wifi be hooked up to a laptop via wifi and use INPA compatible s/w?

Rookie48 10-08-2015 12:45 PM

Update on this issue:

I reset the throttle body adaptations yesterday, drove to home (~35 miles, 99% highway). No codes thrown, truck ran fine (no noticeable difference after throttle body adaptation reset).

Drove to work this AM, no codes, no issues.

I did have another train of thought on this --> the truck uses about 1 quart of oil per 1100-1500 miles. I had just topped off the crankcase (to full level on dipstick) before this all started to happen. In the first 200 miles since topping the oil off, it lost 1/2 quart (no drips, no leaks, out the exhaust I assume). Could the engine somehow, under high vacuum conditions, be sucking oil into the intake when the crankcase is at full level, and thus the issues of misfire could be caused by a short-term fouling of the plugs? That would not suggest why the codes are showing misfire on all cylinders however... and the truck did not smoke when running rough...

Confused... :dunno:

Rookie48 12-07-2015 06:06 PM

Update on this:

Misfires returned after the adaptations reset...

Replaced fuel pump, fuel filter, and regulator. No change.
Replaced CCV valve. No change.
New plugs, coils. No change.
New O2 sensors. No change.
Removed OEtune flash (simply to rule it out). No change. (Actually misfires more now!).
New DISA. No change.
Replaced throttle body. No change.
Smoke tested three times. No leaks. No change.

WTF!! About ready to drive this truck into a pond/lake!!

Still only P0300 - P0306 codes begin thrown...

(Oil consumption has dissipated since CCV replacement. Was only 20K miles on the replaced CCV)


upallnight 12-07-2015 06:19 PM

Get a program that monitor live data while you are driving (I use Torque and Torque Pro)

Looks like you changed everything except what most people would do and that is to check the MAF.

Now don't go pulling the connector to test it like some people would have you do. Look at the MAF g/s at idle, at wide open throttle and when you are coasting. Sounds like you have a MAF that under or over reporting the airflow.

And if you do decide to replace the MAF sensor don't go to eBay or Amazon to buy the cheapest MAF from Wing Wang or Wing Wong. Get a Siemens or VDO MAF sensor.

Rookie48 12-07-2015 07:38 PM

Thanks upallnight!

I have been logging (via OBD Fusion) my trips... I cant say that the MAF is responding correctly since the logging is triggering on the PIDs. Here is a link to this mornings logs if you think it might help...



upallnight 12-07-2015 07:53 PM

Is your MAF setting set to g/s?

@11:19.7 there is no value for the MAF, it is reporting 0. Only way a MAF would report zero if there is no air moving through it. There are other times where the MAF goes to 0.

Just base on your log I think you have a bad MAF.

Can you expand the MAF column (make it wider as in an Excel spreadsheet) so that I can see what value they are listing in the log?

Rookie48 12-07-2015 08:11 PM

The MAF readings are in lbs/min. I've changed the settings to record g/s in the future. The reading you are seeing at 11:19.7 are 0 because I had to shut off and restart the engine to get out of limp mode.

Expanded the MAF column. Dropbox should let you download the file...


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