[daniel06]

Hi all,

My e90 318i has started acting up recently and I can't seem to figure it out.

The problem initially started when one of the spark plug wells got filled up with oil due to a bad VVG. That's when the car first started having misfires in Cyl. 1.
I changed the VVG, Spark plugs & ignition coils as they were pretty old anyways, and after assembling everything back, the misfire was still there.

Couldn't really understand what was going on, so started doing the usual misfire checks:

Ignition coil & spark plug swap
Even though the ignition coils and plugs were new, I went ahead and swapped them around just to be sure.
This resulted in no change whatsoever and the misfire persisted in cyl. 1.

Ignition coil wires
I thought that maybe it was an electrical issue, so went ahead and used a lightbulb that was plugged in to the electrical connector of the ignition coils.
The lightbulb lit up, so I assumed that the cables were working fine.

Compression Test
The compression test showed equal pressure in all cylinders, so I assumed that there were no issues with the compression.

Injector swap
Next thing were the injectors, I swapped them around and same thing, misfire persisted in cyl. 1.

Fuel rail pressure check
Did a fuel rail pressure test and the meter showed around 52 PSI during both idle and acceleration.

This was starting to get frustrating, so I brought up INPA and started looking around for sensor values. The MAF sensor was fine, the O2 sensors were fine, everything seemed normal except for the VANOS values.
The adaptation for the exhaust camshaft was slightly in the red, but after googling I found out that it's a common issue that doesn't necessarily cause constant misfires.



Out of curiosity I moved to the "camshaft positions" tab to check what the output cam is actually doing with the "bad" adaptation value. In that tab, the output camshaft was constantly jumping between 119 and 120 degrees. Which was odd, so I disabled VANOS by disconnecting the solenoids.



Bingo, misfiring stopped. So I started looking in to VANOS issues:

Solenoids swap & Check
I swapped the solenoids around to hopefully see the adaptation issue go to the intake cam, but sadly that didn't happen, and the issue persisted in the exhaust cam. I even manually checked the solenoids with a 9V battery and they seem to work just fine.

VVT Motor Check
Using ISTA+, I performed the VVT motor limit calibration, and the motor learned the limits successfully, so the motor wasn't at fault.

VANOS units lock check
I removed the valve cover to look at the VANOS units as I've read some topic about them being left in the "unlock" positions, so I tried turning them with a 16mm wrench, and they were locked correctly. So that wasn't the issue either.

Timing check
Checked the timing, and the it was spot on.

At this point I'm out of ideas and don't really know what to try. The ECU doesn't help either as it has not given me any useful fault codes during this whole process.

The only codes the ECU has thrown so far:
- Misfire in Cyl. 1.
- Multiple cylinder misfires.

Once in a while the misfire randomly jumps from Cyl. 1 to Cyl. 2 but never to cyl. 3 or cyl. 4.

[NZE90]

What engine do you have? N46 or N43?

[mpower81]

Hi Daniel . you found a solution to your problem I am in the same situation as you