[BrandonIsMyName]

2006 BMW 325i N52 Engine
147XXX miles

Diagram of Engine: https://www.e90post.com/forums/showthread.php?t=1503597

Parts used:
1. NGK (1208) ILZFR6D11 Laser Iridium Spark Plugs
2. MAHLE VS50533 valve cover gasket
3. Victor Reinz Valve Cover Screw Set
Repairs done:
Replaced spark plugs
Replaced valve cover gasket


Backstory:
The car started to idle roughly and hesitate while driving. Soon after I got a misfire in two cylinders.
When I went to replace the spark plugs I noticed cyl 1/3 had oil in the cylinder well. So, I changed the
valve cover gasket. However, I forgot to tighten the 3 middle 10mm bolts (22 bolts total) that held on the valve cover.
All bolts are 10Nm + 90deg
I tried to start the car before I realized the the bolts were loose. It would not crank. NOOOO!
After tightening the 3 bolts I left loose, I tried to crank again. No luck
I checked the spark plug cylinder wells and the valve cover to oil leaks - there was none.
I pulled out the spark plugs, and every one of them had what looked like oil/black residue on the electrodes, not the threads.
I cleaned all of them off, and tried to crank again - no luck
I pulled out the spark plugs again, and all of them had the same oil/black residue on them?

I'm assuming the problem cranking the car has to do with the spark plug electrodes having oil/residue on them - at least
that's my first guess.


Any help would be awesome!

[PichaDis11]

If the Engine will not crank then you have other issues at hand. Ie where crank means there's visible and audible signs the starter is in fact turning the motor. Did you replace the red cable that goes across the engine to the jump start post?

[BrandonIsMyName]

I did replace the positive red cable back. I checked all connections, and everything appeared to be OK.
The engine tries to turn over great.

I ordered some different spark plugs, because I talked to some people who said they had problems with the same ones.
I also ordered new ignition coils (because they have never been replaced, not because I think that is part of the problem)

Any other ideas?

[PichaDis11]

Originally Posted by BrandonIsMyName

I did replace the positive red cable back. I checked all connections, and everything appeared to be OK.
The engine tries to turn over great.

I ordered some different spark plugs, because I talked to some people who said they had problems with the same ones.
I also ordered new ignition coils (because they have never been replaced, not because I think that is part of the problem)

Any other ideas?

Make no assumptions; coils do go bad as too. Check that your plugs are also torqued properly when switching out the coils. I've had that problem with my last spark plug change. Also check that you are getting spark.

The oily residue on the new plugs is concerning. Could it be oil fell into the cylinder from taking out the last set or did you clean before taking them out?

[vaceuf]

You're saying the engine is turning over, and not starting, or that it won't turn over at all?

Silly question, but is your battery fully charged?

[BrandonIsMyName]

Update:

I ordered some other spark plugs I was recommended to as the possible problem.
NGK (6619) LFR6AIX-11 Iridium IX Spark Plug gap .040"
I also ordered new ignition coils:
DECRECH Ignition Coil 0221504463

Got everything back together and it cranks strong, but still no start.

I changed the gap to .044" as someone else recommended. Still no start
I tried to disconnect the IBS (intelligent battery sensor), Still no start.
Checked the valvetronic and starter fuses.

...I'll keep trying other things. I wonder if I need to reset anything on the computer. I don't have a tool to do that though.

[BrandonIsMyName]

It Starts!

I disconnected the Mass Air Flow Sensor and was able to get it started...
However, I let it run for about a minute and it started smoking AHHHHHH!

It ran really inconsistent, and sounded like it was out of oil (low knocking sound)
The smoke definitely was coming from inside the valve cover.
There is no way to check the oil manually, so I just added a quart of oil (0W 40), and tried to start again. the car must be running to check the oil with the on board computer. I'm a little nervous to keep it running for that amount of time.

It started up and ran really rough again, still a low knocking sound, but less smoke than before.

Any ideas?

[Efthreeoh]

It is obvious that you've reassembled the components incorrectly. If all you did was replace parts with new factory-spec parts then the engine should fire correctly upon restart. I'm not sure it is physically possible due to the coil connector pigtail lengths, but any chance you do not have the correct wiring connections to the coils, meaning you've plugged the wrong connector(s) into the incorrect (adjacent) cylinder coils?

Also, what procedure did you follow for replacing the VCG? Did you properly reinstall the Valvetronic motor?

[bluewater328]

When you reinstalled, did you check that the valvetronic was mated properly all the way to the right? Did you try a relearn for the valvetronic? Did you check the ESS while you were there for oil? (you can still check above).

Did You also try an idle relearn?

Want to also make sure you plugged the fuel rail plugs in properly all the way to a click.

Those three center cables have ground rings to them and that makes a difference as much as the other ground cables.

Checked the hoses again? You may have a vacuum leak that's contributing to your problem. PCV comes to mind.

[BrandonIsMyName]

Update:
I have everything running now.

The main problem with the rough engine idle
was the Mass Airflow(MAF) Sensor; which I replaced.

After that, the car ran pretty good, but I continued having issues with
the engine idle. It was not like the MAF idle issue, it was
a problem with the engine reving up and down while in idle.
I took the VANOS solenoids out (2), cleaned and tested them witj
a 12V power supply to make sure they were operational.
So far the idle is back to normal.

Hope that helps anyone having similar complications.

[Three_thirty_I]

Have you scanned for error codes? I'm sure with all of this there will be a collection of error codes that could point to what is happening here. At that mileage, if I was replacing the VCG I would replace the Eccentric Shaft sensor as well, but let's first see what error codes are there, clear and run the car again till it stores new codes. Then you can try and figure out what is going on. This is a grey top N52 like mine, so doesn't have the PCV built into the valve cover, so if it is a PCV issue, then that is located under the intake manifold.