Multiple misfires after plug change!
 

Ok, 2002 X5 3.01 M54 engine.
I replaced the valve cover yesterday. Since I was already there, replaced the plugs as well, I used the Bosch +4, funny thing, those were the old ones as well.
After replacing the plugs, she started funny, I got a check engine light, I ran the codes and it says multiple misfires.
I was wondering if those Bosch +4 need to be gapped? I dont know how that can be done.
Any thoughts?

^I don't like +4's on BMW applications. Prefer to run NGK iridiums.

All +4's should come pre-gapped afaik. Maybe you got a bad set? Or the parts guy grabbed a set off the shelf that isn't the correct part number for your car?

No you do not gap those plugs.

Check all the ground conections coming off the coils.

More than likely you forgot to attach the ground strap correctly. If it was running fine before then something you touched in the process is more than likely the problem.

Misfires
 

I will check that. Are you talking about that little ground wire that is bolted to one of the studs from the valve cover?
I will double check that.
I also do not like those +4 plugs :rolleyes:, When I bought it from Amazon, it said a set of Bosch platinum for BMW X5 , I never paid attention on +4 , I know my fault I hate myself for this :popcorn:

Misfire could be Coil boots thought
 

Your vehicle may have one of two coil types. One has coil boots on the bottom of the coils. Think short plug wires. Their life is 80K max or 5 years. They are cheap. Purchase and replace them. Note: Different ones for BOSCH vs Bremi coils. Aftermarket only makes one version to fit either. Buy the Bosch or Bremi ones, you will be happier.

Pulling the coils out and pushing them back in, is usually the end of the road for the the boots. Now the resistance in the boot is greater than coil output, hence no spark at the plug gap inside the cylinder.

Yes, there is a gap setting on these multi-prong plugs, but it takes a fine wire gaping tool to determine the setting. 99% of the time you are good out of the box but most people view each plug to make sure they were not dropped in transit.

I think we discussed the pros and cons of these plugs in another posting.

Coil Images below: Old style w/ Boot on left, New style on right

Coil Boots Views

The first question we have not asked is, Does the misfire get greater (MORE PRONOUNCED) on acceleration or all the time, idle through 3,000 RPM?

If you put your hand at the tail pipe can you feel the dropped cylinders on each side? (MisFire pulse). Is it random or constant?

Review and thoughts
 

Great video on 3.0 valve cover replacement that makes a point about the EGR vacuum line that runs along the back side of the valve cover. It also show the coil grounds and a few other tips and tricks.
https://www.youtube.com/watch?v=B-TLgNCmTlY