"Pending" P030X codes, occasional engine misfire

[jfoj]

Is the misfire on the hill at your house consistent? Or random?

I am also starting to think maybe a flaky cam or crank sensor?

Does the tach do anything unusual just before the misfires start?

DSC should actually take away throttle, retard ignition timing, possibly apply or modulate brakes, but should not cause misfiring.

Any chance water has gotten in and around coils or injectors? I recall the E53/E70 has some issues with the cowl leaking onto the engine.

Do you have a lot of keys on your key ring? Maybe a flaky ignition switch, I know these are know to do funny things, but would expect to see other signs.

Just tossing some ideas out.

I am scratching my head on this one as well.

[Rookie48]

JFOJ:

Same codes on hill as at highway speeds - P0300 through P0306 - they all get thrown at the same time. Sometimes it throws the codes as pending, sometimes stored, and sometimes it causes the truck to enter limp mode.

Crank and cam sensors were just replaced... tach does not react unusually when condition occurs.

I did not see any water or traces of water at the coils and/or injectors. I guess it is possible.. however the truck has the same issue in dry or wet conditions.

I have one key on the keyring - the truck key - that's it.

[jfoj]

Keep gathering data.

I may have you eliminate some PID's for faster polling at some point.

This is not looking like this is going to be an easy fix.

[Rookie48]

Another log, this time at much slower than highway speeds.

Was out for dinner tonight, short trip from the house. Left the restaurant, and threw codes and limp mode while cruising at about 45 MPH.

Diagnostic report (with freeze frame) and log attached. Log starts after the misfire codes and limp mode, but the truck ran like crap all the way home. Didn't misfire again, but stumbled and surged most of the way home (mainly from 6:01PM to 6:05PM in the logs). Tomorrow it will run fine (guessing, but that seems to be the MO on this truck).

https://dl.dropboxusercontent.com/u/...2015-12-31.pdf

https://dl.dropboxusercontent.com/u/...5%20PM%29.xlsx

Happy New Year!

[jfoj]

I have not looked at the latest logs yet, but what is the crank sensor history?

[Rookie48]

JFOJ, Others:

Crank sensor was replaced 3 weeks ago.

New logs attached again... in the first file I have captured the misfire (limp mode) condition where fuel status = 8. It is at row 647 in the log file. PIDS go to zero during a rolling restart to clear the limp mode condition. Second file has no limp mode, just here for reference.


I have been noticing the engine timing is always around 31.5 degrees when this condition occurs. That may not be an issue, I don't know for sure. I really feel like the engine has a vacuum leak causing the lean condition just off of throttle closed position at higher RPMs. Although it still can happen at lower RPM's, that is where I am normally driving the truck.

Smoke testing revealed nothing, but could there be a vacuum one-way valve that is closed under pressure (smoke test) but failing under vacuum?

https://dl.dropboxusercontent.com/u/...0file%201.xlsx

https://dl.dropboxusercontent.com/u/...0file%202.xlsx

[SarTech]

Watching this thread intently.
Hoping you find the fix, I think your fix will also be my fix.

[upallnight]

Do you look underneath the car when you perform the smoke test? There is a vacuum line that goes to the fuel filter/pressure regulator. It is the F connector that attaches to the rubber intake boot before the throttle body.

[Rookie48]

Going off what JFOJ suggested earlier in the post - and the only thing we didn't yet replace/inspect/clean are the fuel injectors. Could a single dirty/partially restricted injector create a situation where the cylinder is very lean, and the extra air pumping into the exhaust causes multiple cylinder misfires?

Since the truck idles fine, and typically runs normal (but not always, not always smooth running somedays, but not throwing codes or limp mode either), the injectors have been the last thing we are focusing on.


Rookie48

[Rookie48]

Uppallnight:

What and when should that vacuum line be pulling vacuum? I had the vacuum gauge on it today (via a tee connector) but at idle and revving to 3000 rpm produced no vacuum on my gauge. Engine was at operating temp....


2003 X5 3.0i Sport MT
2004 M3 Coupe
1997 M3 Coupe