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      01-09-2019, 05:36 AM   #1
Mircea
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[FIXED] N53 weird misfires (rough idle & rare power loss)

FIXED: After replacing the valve cover gasket, all 6 coil packs and all 6 spark plugs to no avail, what finally fixed it was replacing all 6 injectors... I don't know if it was only the injectors that fixed this but doing all that and the injectors last sure did.

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Hi,

This is my first post in here and what a way to begin

As you could read from the title, I am facing a pretty common issue with my completely stock 2008 E92 325i (N53), but which acts a bit more weirdly than other people's cars here from what I could see, so if the post seems a bit long it's because I feel like I need to detail what exactly is happening and how.

I got it 6 months ago, it has 78k miles and from what I can tell everything is OEM on it.

The symptoms are as follows:

Rough Idle

I am constantly getting rough idles (slight misfires I guess only on one cylinder) every time I start the car from cold. Once it warms up after about 10-20min driving, everything seems to be fine and RPM stay as smooth as butter at ~550.
I have an OBD reader but it reads no error codes for when this happens.

Power loss

First about three months ago, it happened while driving (accelerating). Additionally, a check engine light came up so I stopped on the side of the road and plugged in the reader. It read a Misfire on cylinder 2 and it was idling pretty rough (~300RPM bounce).
Weird thing is, immediately after this, I stopped and started the engine and the misfire was gone, drove for ~1h with absolutely no problems whatsoever.

Swapped the coil packs between themselves (cyl2 was swapped with cyl1)

It then happened again after about two weeks, this time a misfire on cylinder 4, again after a restart the car was perfectly fine for the rest of my drive.

Because the misfire didn't follow the coil pack and didn't happen on the same cylinder that misfired the first time, it makes me think that it may be random?

Possible cause?

When swapping the coil packs around, I noticed there is oil inside the coil pack chambers of cylinders 2, 3 and 4. (you can notice a spot of oil outside of it too.
View post on imgur.com



Compared to cylinder 1's which is apparently clean.
View post on imgur.com


The car does not smoke, but does indeed consume a lot of oil in my opinion (1L every ~1000km). There is no oil under the car either, and I put my flashlight as far down the engine bay as I can and couldn't notice oil down there either.

This suggests that the valve cover gasket might need replacing?



There is also a strong smell of gas every time I start up the car and even more so when it's done from cold.

This suggests leaking injectors?


Here is a video of the idle when it's cold (filmed in September):



Again, the thing that baffles me is that the car is very much driveable, put about 3k miles on it since I got it and the rough idling, gas smell and everything else goes away after the car warms up if there's no serious issues during the drive such as the power losses mentioned above which happened only twice in 6 months...


Any help with this?

Thanks and sorry for the long post.

Last edited by Mircea; 03-07-2019 at 10:01 AM..
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      01-09-2019, 07:06 AM   #2
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Quote:
Originally Posted by Mircea View Post
Hi.
I think you are on the right track.

It does seem like you have a leaky gasket, which allows oil into spark plug tube and causes misfire.

I would recommend doing some basic matenance first and see what happens. Inspect your gaskets as they tend to leak (valve cover, oil filter housing, and inspect oil pan gasket) and replace as needed. Change your oil. Clean your vanos solenoids, change your spark plugs, replace any bad coils, inspect your injectors (clean or replace as needed), change your accessories belt, air filter. Also, since you have n53 engine (direct injected), from what I read, they are also prone to carbon build up. So you might want to inspect your intake manifold and see if it needs cleaning. Not related to your issues, but change out your coolant as well (itís supposed to changed every 2 years).
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      01-09-2019, 08:37 AM   #3
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As stated looks like one issue is the valvetronic motor gasket is leaking. This would definitely account for a rough idle as it results in a vacuum leak not just an oil leak.

I had a leaking valvetronic motor gasket and had the rough idle and misfires too. I didn’t think the misfire was related to that’s gasket but I can tell you this, once I stopped that leak with a carefully installed new valvetronic gasket I had no more misfires, rough idle, or any issues whatsoever. Replacing that gasket is a good place to start and is an easy 1-2 hour DIY depending on how handy you are.

The oil loss is that gasket leaking and dropping oil down onto the headers where it is largely burned off. And it only leaks when the motor is running that’s why you don’t see drops on the ground.

A fuel smell is another issue altogether and leaking injectors are definitely a recurring issue on the direct injected BMW motors.
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      01-09-2019, 09:52 AM   #4
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Quote:
Originally Posted by Biginboca View Post
The oil loss is that gasket leaking and dropping oil down onto the headers where it is largely burned off. And it only leaks when the motor is running thatís why you donít see drops on the ground.
This wouldn't fix the oil I took a photo of, in the coil pack chamber, would it? I thought that was caused by a bad vcg.
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      01-09-2019, 10:56 AM   #5
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[QUOTE=Mircea;24214147]This wouldn't fix the oil I took a photo of, in the coil pack chamber, would it? I thought that was caused by a bad vcg.[/QUOTE

Iím sorry I just realized the n53 doesnít have valvetronic motor. So yes you are looking at replacing the valve cover gasket in your case, which would address that oil in the spark plug areas.
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      01-10-2019, 02:15 AM   #6
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Check the spark plugs after leaving car overnight. If you see any fuel on them then you know you have a leaky injector which would explain misfires.

I had the same issue like you and it turned out to be a injectors.
It started off with rough idle on cold start ups (but not error codes!) and over the next few months it got significantly worse. Every single cold start up resulted in EML, error codes and vibrations over the first 10-20 min of driving.

I ended up replacing 3 injectors in bank 1 (cylinders 1-3) with the latest index 11.

However the oil consumption, that's another problem that needs to be addressed.
I would have the garage to check for leaks because 1L every 1000km that's way to much.
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      01-10-2019, 03:13 AM   #7
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+1 on Mahoone's suggestion. I'd put money on this being injectors. Known issue with the N53. So much so that BMW have upgraded the injectors for this engine eleven times!

And read this thread:

https://www.e90post.com/forums/showt...5#post23587995
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      01-10-2019, 05:40 AM   #8
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Oh no, the thing I dreaded the most, injectors...

Thanks, that thread is really helpful but seeing as I am not a mechanic or handy at all with any kind of hardware unless it's electronic, I will most probably just go to a local garage.

So, so far I should:
  • change injectors
  • change coil packs
  • change spark plugs
  • replace valve cover gasket

And I guess I'll have to get all work done at once for labor cost to be most effective, since changing the vcg means taking the whole top off the engine.
I've been quoted labor for the vcg change alone around £600 in the past...

Still, I'd like to buy the parts myself as they'll be the biggest hunk of money on the total, and I do not know which garage would let me bring my own parts to them for fitting...

Do you have any suggestions of good indys/garages in South England, preferably west, Berkshire area?
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      01-10-2019, 08:16 AM   #9
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With the list like that you'll be looking at around £2000

If it was me, I would try to locate the oil leak first and go from there. Unless you don't mind paying to have it all done in one go.
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      01-10-2019, 09:42 AM   #10
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Quote:
Originally Posted by mahoone View Post
With the list like that you'll be looking at around £2000

If it was me, I would try to locate the oil leak first and go from there. Unless you don't mind paying to have it all done in one go.
I know, it's a ton of cash to dump at once, especially since I'd preferably want to get all 6 index 11 injectors brand new and unused...

I am pretty positive the oil leak is caused by a bad valve cover gasket, and for changing that alone I was quoted £600, so around £700 with the part and other expenses.
From what I saw from YouTube, the top of the engine needs taking off to replace the vcg, so I thought it would be a good idea to just force myself a bit into getting it all done at once with the vcg.

But going one by one would be easier on the cash and yeah I'd ultimately prefer this.
At the moment I guess the vcg needs doing anyway so while I'm there I guess I could technically have the coil packs and spark plugs replaced as well even though I confirmed with BMW and these have been recalled and replaced by them in the past. Then again, there's no telling what damage that oil in their chamber has done to them over time, here's how one of the coils that had oil in their chamber looks like

What do you guys think? I think all these would be a good idea for the first step of fixing it and I'd round out at about £1000 if not less, depending on the garage.
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      01-10-2019, 05:40 PM   #11
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Any recommendations for the best place(s) to buy injectors?

Many thanks.
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      01-11-2019, 03:30 AM   #12
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Try Merlin Diesel Systems or Cotswold BMW who do a discount for forum members.
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      01-11-2019, 06:16 AM   #13
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Seeing as we started with recommendations

Quote:
Originally Posted by Mircea View Post
Do you have any suggestions of good indys/garages in South England, preferably west, Berkshire area?
I am really looking for good indy mechanics/garages, got tired of being scammed or ripped off by big brands for mediocre quality servicing.
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      01-12-2019, 03:34 AM   #14
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I can 100% recommend Bromspec:

http://www.bromspec.co.uk/

I have no connection with the firm other than being a customer for about 6 years. Great guys, all ex-BMW, really know their stuff, use genuine parts and prices are fair.

Also had a bit of work done by Iridium:

https://iridiumengineering.co.uk/

Don't know them well, but they seem to know their stuff.
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      01-14-2019, 05:36 AM   #15
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Thank you

I've however gone for something a bit more local, at some of my mates' recommendation.

http://bmwspecialistreading.co.uk/

Got this booked for 4th of February, will feed back to this thread with how all this goes.
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      02-05-2019, 03:14 AM   #16
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Just got the car back from them yesterday. They were pretty professional and their garage looks pretty cool. Good value for money also, for 6 spark plugs, 6 coil packs and a valve cover gasket change only a bit under £600.

Unfortunately it didn't fix the rough idle... They too said that the next step would be injectors, and they recommended I change all of them at once as at least one of them is bad and leaking overnight...

Question now is, should I really worry about this misfire damaging the new spark plugs if I run it like this for, say 3 more months? Again, symptoms are the same, rough idle that (completely) clears after a maximum of 5 min of running.
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      02-05-2019, 03:39 AM   #17
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Quote:
Originally Posted by Mircea View Post
Just got the car back from them yesterday. They were pretty professional and their garage looks pretty cool. Good value for money also, for 6 spark plugs, 6 coil packs and a valve cover gasket change only a bit under £600.

Unfortunately it didn't fix the rough idle... They too said that the next step would be injectors, and they recommended I change all of them at once as at least one of them is bad and leaking overnight...

Question now is, should I really worry about this misfire damaging the new spark plugs if I run it like this for, say 3 more months? Again, symptoms are the same, rough idle that (completely) clears after a maximum of 5 min of running.
I would not be worried about spark plugs, I would be worried more about rod bearings. On the direct injected n54 when the rod bearings have gone out the cause has frequently been traced back to bad injectors leaking fuel, and that fuel contamination of the oil resulted in spun bearings.

So if the N53 is like the n54 then not fixing the leaky injectors could cost you a lot more than a spark plug, it could cost you a motor replacement.
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      02-05-2019, 04:11 AM   #18
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Quote:
Originally Posted by Biginboca View Post
I would not be worried about spark plugs, I would be worried more about rod bearings. On the direct injected n54 when the rod bearings have gone out the cause has frequently been traced back to bad injectors leaking fuel, and that fuel contamination of the oil resulted in spun bearings.

So if the N53 is like the n54 then not fixing the leaky injectors could cost you a lot more than a spark plug, it could cost you a motor replacement.
Sweet Jesus, this made me shit myself a little.

I should do this in a hurry then I guess...
What's your opinion on changing the injectors only on one bank first?
Would that not ruin the new injectors as they'd have to work with older ones on the other bank? I've read and heard so many different opinions by mechanics and users on the forums on this issue I have no idea what to believe anymore.
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      02-05-2019, 05:36 AM   #19
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Quote:
Originally Posted by Mircea View Post
Sweet Jesus, this made me shit myself a little.

I should do this in a hurry then I guess...
What's your opinion on changing the injectors only on one bank first?
Would that not ruin the new injectors as they'd have to work with older ones on the other bank? I've read and heard so many different opinions by mechanics and users on the forums on this issue I have no idea what to believe anymore.
Iím not qualified to comment on that. Hopefully someone knowledgeable will chime in...
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      02-05-2019, 08:24 AM   #20
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If you went to any BMW garage they would replace all 6 injectors. No matter if 1 is faulty or 3. That's because it is a official recommended solution to a leaky injectors problems on those engines. You can confirm that by running injectors test in ISTA D.

You can replace them in banks like I did but eventually the old injectors will fail. So if I were you I would replace all 6 in one go.
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      02-05-2019, 09:05 AM   #21
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Quote:
Originally Posted by mahoone View Post
You can replace them in banks like I did but eventually the old injectors will fail. So if I were you I would replace all 6 in one go.
I am not too worried about the old injectors as I plan on changing them anyway. I am just concerned about massively wearing the new ones off because I'd run them for 2-3 months with the old ones on the other bank until I eventually change them too...
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      02-06-2019, 06:56 AM   #22
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Quote:
Originally Posted by Mircea View Post
I am not too worried about the old injectors as I plan on changing them anyway. I am just concerned about massively wearing the new ones off because I'd run them for 2-3 months with the old ones on the other bank until I eventually change them too...
Having the old injectors in the bank 1 (or 2) won't affect the new ones in another bank. So you can have x3 index 11 injectors in bank 1 and old injectors (index 8?) in bank 2.

New injector would be only affected if you replaced 1 faulty injector in one bank and leave the old ones still in i.e.: 5 old injectors and 1 new. Exception to that would be if you had 6 index 11 injectors (latest ones) and one of them failed - then you only replace 1 faulty injector.
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