Misfire Cyl 4-6

[awns729]

Hey guys,
2008 N54, 70k miles. Carbon cleaning done recently and spark plugs changed. Recently discovered that my CPO car had a JB4 installed when I bought it and so I turned that to map 5. After a few weeks of that, I've been getting Cyl 4,5,6 misfire codes only on cold starts. Before I discovered the JB, I'd been running cobb stage 1 aggressive with no issues.

I'm still waiting on my JB4 cable so I can update to the latest software, but I don't know if that would cause misfires? (It has to be 2+ years old since it came with my car)

What should I do next - coil packs? all 3?

Thanks!

[mike@x-ph.com]

Originally Posted by awns729

Hey guys,
2008 N54, 70k miles. Carbon cleaning done recently and spark plugs changed. Recently discovered that my CPO car had a JB4 installed when I bought it and so I turned that to map 5. After a few weeks of that, I've been getting Cyl 4,5,6 misfire codes only on cold starts. Before I discovered the JB, I'd been running cobb stage 1 aggressive with no issues.

I'm still waiting on my JB4 cable so I can update to the latest software, but I don't know if that would cause misfires? (It has to be 2+ years old since it came with my car)

What should I do next - coil packs? all 3?

Thanks!

Start by changing spark plugs.
I recommend changing all 6.
If misfire continues, switch ignition coil number 6 to cylinder 1 and see if 1 starts misfiring.

[BadOneThreeFive]

Originally Posted by mike@x-ph.com

Start by changing spark plugs.
I recommend changing all 6.
If misfire continues, switch ignition coil number 6 to cylinder 1 and see if 1 starts misfiring.

He already stated that he changed the plugs..

+1 on changing the ignition coils around to see if the codes move.

[Silenus]

Injectors, bank 2.

[awns729]

So I have a strange update.

Swapped around the coils in such a way that I'd be able to isolate if it was a coil causing the cylinder to misfire (and possibly affecting the cylinders around it (if this is even likely or possible?). From memory (I forgot where I wrote it down lol):
swapped coils 6 and 3
swapped coils 5 and 1
and swapped coils 4 and 2.

Anyway, as I was swapping them, I noticed a lot of caked on "dust" that must have been from the dielectric grease I used. I just smacked it off and reinstalled them. No codes at the moment. Possible lesson: don't use grease on the coil -> plug connection?

ECS tuning pictures the same grease in their picture, and so I thought it was fine to use: http://www.ecstuning.com/News/BMW_N5...013/ES2581944/

But I'm wondering if its actually the grease causing a poor connection and misfire since it had all dried up and turned into powder. I noticed no stuttering on cold starts and no codes for the few days after, but I'll recheck the codes tomorrow (since its running better I forgot to check the codes recently).

Figured I'd update and see what people think.

[JimUlrich135]

Start with six coils. Don't even think about injectors until coils are replaced.

[Dackelone]

Most people say the coils are only good for 70K to 80K anyways.

Did you use BMW dealer bought spark plugs? Just bc a part is new doesn't mean it is a "good" part. You could try switching spark plugs from a known "good" cylinder.

On past bmw's I would use a water mister to spray down the (tops of the)coil packs... to see which one would arc/miss. I am not sure IF that would work on the newer engines since the coil packs sit so tightly in the holes(bores).

Lastly... any oil leaks from the valve cover? Or oil down inside the coil/plug holes?


Dackel

[awns729]

Codes still haven't come back as of yesterday, even with JB4 map 5 and also with map 0 (pass through). I've probably put 1000 miles on the car after swapping the coils and smacking out the dust from the dried up grease. Maybe it's safe to assume it was the dielectric grease causing the codes?

Yes, dealer bought plugs Dackelone. Since the misfire code is still gone, I think for now I'll assume that dielectric grease was the culprit and maybe using it is a bad idea. If the misfire comes back, I'll probably order 6 coils like you and Jim said and maybe also swap around plugs if necessary and double check the gap.

When I did the plugs 3-4k ago I don't recall seeing oil in the holes and I haven't really looked around the valve cover area but I can check next time I'm in there.

Thanks!

[ShocknAwe]

Dont use dielectric grease in any conductive environment. If that got down by the terminals I'd see why you would have been having an issue.

[awns729]

Originally Posted by ShocknAwe

Dont use dielectric grease in any conductive environment. If that got down by the terminals I'd see why you would have been having an issue.

Well according to this (scroll down to see the second comment), it should have been fine to use it: http://www.amazon.com/review/R26URGV...wasThisHelpful

I think the problem in this case was that it gets too hot and the grease didn't stay greasy. But I think in other cars running at lower temperatures, this wouldn't have been a problem.

Usually (on my wrx) I just put a bit of grease in the boot and put it back not worrying whether any gets on the metal (even expecting it to get on the metal), since as the comments say, the grease insulates all but the strongest electrical point. Similar to putting grease all over a battery terminal.

[MightyMouseTech]

There is a big difference between 12V and 20,000V.

Did they have grease from the factory? No? Then put them in dry.

[JimUlrich135]

Coils are not greased from factory but a little sylicone spray around the outside of the coil to help lube old, dry rubber and aid in installing a coil into the bore isn't a problem. Most of the time greasing a coil(where plug goes into)results in it "jumping off" the plug, thus causing yet again, another misfire...not always but frequent enough!

If you do end up replacing all coils(since plugs were done already and coils are the next cheapest/necessay route in a car with higher miles), I would just used compressed air to clean coil bores out and slide the pretty new coils in dry, no need for lube when they're new. As for swapping around plugs, wait until after coil replacement just to save time. Swapping around plugs may be unecessary if replaced recently. I'm telling you, start with coils!