2005 E53 3.0 Misfires

bxturbo · #1 03-24-2015, 11:25 AM

Hi all,

Yet another misfire thread, but this one has me stumped as the car idles fine and starts fine even on the coldest of mornings. My e53 3.0 with 100k miles misfires under load at wot. Particularly on a hill, but sometimes on even ground also.

I have changed the plugs and swapped around the coil packs and initially it was only cylinder 6 misfire. At that point I could not even get it up to highway speed without misfiring.

I cleaned the MAF sensor and threw some techron fuel injector cleaner in the tank and that made it better for a while, as in I could now reach highway speeds. I did not realize being on an incline makes such a difference triggering it, so I just drove around town and on level freeways around the house and everything seemed to be fine. Fast forward another couple of weeks and as soon as I hit an incline on the highway it would misfire.

New MAF sensor, new DISA valve, new oil separator and return hoses. New intake boot. Cleaned ICV, Throttle Body, air distribution piece with new o-rings. Took it for a test drive and took it up to redline and it did not misfire. I was so happy!

But as soon as I came up on an incline on the highway and opened the throttle, it misfired again. As soon as I exited the freeway and hit a stop light the misfire stopped and the "Service Engine Soon" light went off (usually I'd have to shut it off and restart it for the light to go away and the cycle to restart). This time my basic code reader detected a misfire on cylinder 4.

What should my next step be? The only thing that seemed to make it better was the bottle of Techron and cleaning the MAF initially because that improved it enough to bring it up to highway speeds again, but not enough improvement to stop it from misfiring under load on an incline. Now that I replaced the MAF with a new one, my guess is it was the Techron that was responsible for that initial improvement. Not sure if I'm overestimating the difference the Techron might have made. The car runs and drives great otherwise.

Am I missing something here? Thanks in advance for any suggestions.

Brads2002 · #2 03-24-2015, 12:19 PM

Not sure how long ago you did the plugs but you may want to check to see if they have backed out. If they are not torqued to the right spec they will back out and cause a mis fire under load. I think the spec is 21lb.

Last car I was working on showed multi misfires across many cylinders along with o2 codes. It had a cracked valve cover.

Possible you moved coil 6 to coil 4?

bxturbo · #3 03-24-2015, 02:46 PM

Quote:

Originally Posted by Brads2002

Not sure how long ago you did the plugs but you may want to check to see if they have backed out. If they are not torqued to the right spec they will back out and cause a mis fire under load. I think the spec is 21lb.

Last car I was working on showed multi misfires across many cylinders along with o2 codes. It had a cracked valve cover.

Possible you moved coil 6 to coil 4?

I did the spark plugs at some point in January. I will double check they are all torqued to spec. The car was misfiring prior to me touching anything. I only changed the spark plugs in an attempt to fix the misfire issue.

I had a spare new coil and swapped that on 6. Still misfired on 6. I took out the new coil from 6 on the off-chance it was faulty although it was brand new and swapped it with 1, and the misfire stayed on 6. The first time I've seen the misfire move to 4 was last night. Prior to that, it was always on #6.

No other codes such as o2 present. Only one code was pending when I hooked up the scanner yesterday and it was for Cylinder 4. I do not see any oil around the valve cover gasket and the spark plugs were all dry when I pulled them.

Brads2002 · #4 03-24-2015, 07:37 PM

I would def check the plugs. I have had that happen to me before. Sounds like the problem has improved from where you started.

I doubt its fuel related but the techron seems to help. Have you changed your fuel filter? At 100k its a good idea. Be careful not to break the plastic little clamps. There is a method to remove them, i think its squeeze to the side but can't remember exactly.

bxturbo · #5 03-25-2015, 12:52 PM

Thanks for the input. I will check the plugs again and change the fuel filter. I just got the car a few months ago, so I have no idea if it's ever been replaced. Will report back once I put in a new fuel filter.

bxturbo · #6 03-31-2015, 04:39 PM

Update - So I finally I took it to a BMW specialist. They smoke tested it and found one of the caps at the back of the intake manifold had cracked. Here is a thread with more info on the caps I believe they replaced: M54 vacuum tubing ... what diameter ... what brand ... what material ... what length? - Page 2 - Bimmerfest - BMW Forums
No problems since getting it back. Hopefully that's the end of it.

Brads2002 · #7 03-31-2015, 06:03 PM

Thats great! Glad it was an easy fix.

bxturbo · #8 04-01-2015, 12:11 PM

Quote:

Originally Posted by Brads2002

Thats great! Glad it was an easy fix.

Easy fix, but expensive diagnostic. They checked fuel trims, cleared and reset values in the computer, checked fuel pressure, and finally smoke tested it. It was not a cheap answer to my misfiring question by any means.