P0300, P0302, P0304, P0306, Engine running rough with little power

[jfoj]

Most of the bad fuel these days has too much Ethanol in it. But like anything, "The solution to pollution is dilution". 1 decent fill up should sort any fuel related problem for the most part.

Did the vehicle go through a car wash before any of this happened?

The issue with the water leaking may not specifically be with the 6 cylinder gasoline engines, but I know it can and does cause problems with the 6 cylinder Diesels as I recall.

The water does not leak right at the base of the windshield, it actually leaks right at the back edge of the hood, right around cylinder 4 or 5 as I recall.

Good luck, this should not be so difficult, but it will be interesting to see what in the end was the primary problem.

[pshovest]

I'd forget the smoke test. If you had a vacuum leak or other intake issue causing intake air to bypass the MAF, the car would run better with MAF disconnected.

[ard]

When something 'breaks' on a car, it is fine one day, then - in a moment- something happens and you get a miss, a CEL, whatever.

There is almost certainly SOMETHING that occurred at that time... "I turned right". "I passed an AM/PM market"..."The cell phone JUST rang"...or "I filled up the tank one hour before (or 30 minutes or the day before)".

These are usually not causal events.

In a million plus miles of driving I have never had 'bad gas' that caused a CEL.

[X5Cat]

Originally Posted by ard

In a million plus miles of driving I have never had 'bad gas' that caused a CEL.

Yeh, I have probably driven at least 2 million miles, and I have only seen it once. It only seemed to affect one type of engine design, namely late model (late 90's or early 2000's at the time) GM's with pushrod actuated valves. Tons of them within a couple of days and a 75 mile radius or so, with pushrods turned into spaghetti, so the dealership garages told me. Which reminds me now, that is how I found out about the fuel problem then, from the dealership. They brought it up to me while I was buying new pushrods. It may be a long shot, but I may check with them to see if any others have had the same problem lately. Seems like I have read some on these forums about bent or worn levers (was that the correct part name?). Do such parts have an analogous function to the pushrods in other engines?

[ard]

when I hear hoofbeats, I don't think 'zebras'

[X5Cat]

Originally Posted by ard

when I hear hoofbeats, I don't think 'zebras'

If you're laying on your back catching a snooze on an African plain when you hear them, you should maybe at least consider the possibility.

Just spoke with the local BMW service manager. Hasn't heard of any recent fuel problem as I described. He did volunteer that 9 out of 10 times when they start missing like this, it will be the coils. When I expressed doubt that two would go out at the same time, he laughed and said don't bet on it. So, tonight, I will be juggling coils in search of a pair of gremlins.

[ard]

True Dat.

So misfires can be a pita.

The DME uses the velocity of the crank- or more accurately the acceleartion of the crank after each ignition to DECIDE if there was a misfire...if the acceleration after any given cylinder firing is over a set threshold, it trips an error. I seem to recall if it is very bad- like a solid miss- you get a specific code. So there is 'misfire' and 'misfire with lean' or something like that. What that MEANS in BMW land is they they shut off the fuel to that cyl. Further confusing things some places the BMW code is presented as "misfire on warm up"...notably in the Peake venacular.

I had a misfire that was quite hard to track down. This in an S62. Oddly changing the coils change the PATTERN but not the precise cylinder. Apparently the DME on the older S62 is not very good at determining crank velocity and acceleration abnormalities, sometimes it was thinking the issue was the cylinder before or after the bad one in the firing order...so it would get the cyl numbers wrong. Tracked it down using INPA and the "Cylinder unrest" function, this looks at the variation in eacy cylinders firing pattern, basically a per cylinder crank accel map. $30, one new coil..nailed it.

Here were the codes:

B2 Catalyst system efficiency, Cyl #1-4"
C4 Misfire, Cyl #1"
CD Misfire during warm-up, Cyl #1
CF Misfire during warm-up, Cyl #3
D0 Misfire during warm-up, Cyl #4
D2 Misfire during warm-up, Cyl #6
D4 Misfire during warm-up, Cyl #8
D5 Misfire during warm-up, multiple cylinders

That last code look familiar? I think that maps to a P0300

and FYI image:





FYI it WAS cylinder one, with a single bad coil. Fixed 35k ago....

Zebras.




Edit...let me add that in hindsight it is easy to look like a genius. BUT. Do you want to know what I replaced PRIOR to getting INPA running? Plugs, fuel filer, FUEL PUMP (at $360).... all stuff that I said "well, just think of this as maintenance"...

[X5Cat]

Eureka! Tip of the hat to pshovest, this really fooled me with 2 coils going out at once. I swapped Coil 1 with Coil 4, and Coil 3 with Coil 6. Now I have misfire codes at cylinders 1 & 3, so apparently bad coils were at 4 & 6. The service manager I spoke with earlier today recommended to replace them all. So, I'm shopping! Thanks to all, you all helped to nudge me to this point. jfoj, I'm glad I have the OBD Fusion now, regardless, and my MAF would probably still be dangling loose if you hadn't noticed on the log.

ard, really insightful stuff on the acceleration/misfire stuff. Note that early on in this thread I was wondering exactly what misfire meant in terms of codes read. I didn't know if the code was triggered by the simple fact that no electrical spark was occurring, or if there could be spark but yet no combustion in the cylinder. Now I understand how the misfire code can mean no combustion, spark or no.

[jfoj]

I guess it does happen, but not often that 2 can go at one time. I just do not see this often at all.

Even when you get the coils replaced, it is worth Logging again to get a new baseline.

Still a bit curious why the first 3 plugs were so carbon fouled as well.

I find the closer you look at any vehicle, the more you find!

[ard]

Originally Posted by X5Cat

Eureka! Tip of the hat to pshovest, this really fooled me with 2 coils going out at once. I swapped Coil 1 with Coil 4, and Coil 3 with Coil 6. Now I have misfire codes at cylinders 1 & 3, so apparently bad coils were at 4 & 6.

You can have ONE bad coil, and when you move it you move misfires to MULTIPLE other coils. Your test does not NECESSARILY tell me you have two bad coils.

AFAIK your fire order is: 1-5-3-6-2-4 .... so 1&4 are neighbors as are 3&6

If it was one, or two, coils replacing all will certainly fix it. But I would put money on only one being bad.