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?

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.:D

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.

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:



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

and FYI image:

http://www.m5board.com/vbulletin/att...895resized.jpg



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"...

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.

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!

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.

Totally agree on the above.

When moving coils it is best to understand the firing order and only move a single coil at a time and move it 3-4 cylinders away in the firing order depending on 6 or 8 cylinder engine. Adjacent misfires in the firing order are often suspicious as ARD pointed out.

Doing this will help you identify a single coil problem as may get the engine smoothed out while you wait for a part.

During the process, you can check the coils and compare readings with an Ohmmeter, just be careful many of the modern coils have an internal resistor or diode for DME monitoring, this is why it is often best to compare resistance to other coils in the vehicle as well as check the coils with the Diode check mode on the meter with the leads in both directions.

But also keep in mind arc problems may be the problem that will not typically show up during a resistance test. Arc problems can be due to cracks and/or bad coil boots. Check carefully for cracks and carbon tracking.

None of my misfires were adjacent (4 & 6, then 1 & 3), neither physically nor in the firing order. I took the SM's advice and ordered a full set of Bosch coils, supposed to be here later this week. I ordered online and not through stealership, though, so I hope they are not counterfeit. The seller has a long history and a very positive reputation, so we'll see. These coils are supposed to be "updated"(?). I may try just replacing the coils at the misfiring cylinders first just to see what happens. Will let you all know how my luck runs on all of this. After all this misfire business is settled, I want to chase down the little electrical and evap code gremlins, on different threads.

Evap code may be a problem with the fuel pump.

Suggest you read this thread below. You may want to just pop the fuel pump, connector off while the vehicle is down. Notice the discolored pin on the fuel pump power connector.

http://www.xoutpost.com/bmw-sav-foru...mall-leak.html