Misfiring in all cylinders

Hello everybody, i'm new to this forum, hope i'll find an answer to my problem.

I have bought a used BMW E46 engine 325i 2004 with 110K since 8 months, it was just fine until i noticed an unexpected behavior of the engine when travelling at 100 Km/h. I feel like the engine is chopping and the RPM is alternating or rising intermittently although my step on the throttle is constant. When this happen, i step more on the throttle to accelerate, i feel a strong knock on the back of the car.

I also noticed that the fuel consumption is high. There is no strange noises from engine and it starts normally. The incident only happens when travelling. I took it to the garage and the DTC showed misfire in all cylinders.

i presented the car to different garages and they have different expectations: Manifold, Fuel Pump, Spark Plugs, ....etc.

P.S I have changed the spark plugs, air filter, oil filter, fuel filter 6 months back.

PLEASE HELP ...!!!!

I would say fuel pump.

I replaced the pump but didn't resolve the problem

There was an ignition coil recall. Do you know if yours were changed?

There was a leakage in one of the spark plugs, so i have changed the coil 2 weeks back and still the misfiring occurs at the replaced coil as well. Could it be the battery or battery cable head?

Originally Posted by y.alkhateeb

There was a leakage in one of the spark plugs, so i have changed the coil 2 weeks back and still the misfiring occurs at the replaced coil as well. Could it be the battery or battery cable head?

Coil?

You have six of them, one on each plug.

Get the codes read and post them.

Yes, i have replaced the coil and spark plug for cylinder 2, and still reads the same error
ignition, activation coil cyl 2
ignition, activation coil cyl 4
ignition, activation coil cyl 6
ignition, activation coil cyl 1
ignition, activation coil cyl 3
ignition, activation coil cyl 5

You clearly have an ignition issue. It is doubful all of your coils are bad. Double check your coil connectors and the pigtails that push onto the plugs.

Double-check to make sure all your ground straps are tied down. IIRC, there is one at the front and one at the rear.

Originally Posted by J. Kidd

Double-check to make sure all your ground straps are tied down. IIRC, there is one at the front and one at the rear.

There are nice pictures of the M54 ground straps here ...
- Pictorial DIY for an M54 spark plug replacement

Normally when ALL are misfiring it's a bad ground wire. That's from my experience at least.

Thanks all for your reply, i'll try to check the grounding straps but any idea where to find those straps for the E46? Furthermore, i have read over another thread is that its possible to be an air leak from the air intake tube or hose connected to the CCV? any idea to simply check those things?

This misfire is driving me crazy ...

Guys .. could it be the DISA or its not possible that it cause a misfire in all cylinders?

You have an ignition issue, not a fuel mixture issue.

Could it be that the valve cover Gasket is damaged and that the oil is leaking to the plugs and coil causing a misfire in all coils? Just thinking loudly ...

Originally Posted by malibumafiav

normally when all are misfiring it's a bad ground wire. That's from my experience at least.

1+

Is the red wire a grounding strip? or its somewhere else? if yes how to replace it? its going into the plastic duct.

Moreover, why i only feel the misfire and engine cut offs only between 80 - 120 Km/hr and rarely at 60 Km/hr

Agreed. Check ground wire

Originally Posted by MalibuMafiaV

Normally when ALL are misfiring it's a bad ground wire. That's from my experience at least.