Engine runs rough after valve cover/TCC replacement

[Multibeemer]

I know, this could be any one of a million things, but after finally finishing the valve cover/upper timing chain cover replacement on my 03 4.4i, it has a very rough, unsteady idle which doesn't smooth out as I rev the engine. The job was complicated by the fact that I dropped the timing chain tensioner plunger into the lower timing chain cover, which required me to take a ton of stuff off (alternator, water pump, PS pump, belts, front pulley, etc.). The symptom sounds very much like a vacuum leak, but so far all the hoses I've checked are tight. The other symptom is that the service engine soon light is on, and it systematically cycles between being continuously illuminated, and flashing. Could this imply a loose sensor connector? The SES light wasn't on before I started the project. I haven't taken it to an auto parts store yet to get the codes read, because I hesitate driving the vehicle with it running so rough, but depending on the opinions I get, that could be my next step. Thanks in advance.

[upallnight]

did you unplug any wires? Could be a loose connection or something incorrectly plugged in.

[Multibeemer]

Originally Posted by upallnight

did you unplug any wires? Could be a loose connection or something incorrectly plugged in.

lol - only about 20. But so far, everything seems to be plugged back in correctly. I really need to have to codes read to narrow down the area the problem might be coming from, but the auto parts stores aren't open today.

[David.X5]

I feel for you.

Its probably worth checking your spark plugs look ok and are properly tightened with the coils well seated. The spark plugs were the source of my last mystery roughness....

The previous "mystery" was finding the check valve in the vacuum line (white/black plastic connector, about as big around as a quarter) was reversed...

[Multibeemer]

Hmmm... Interesting theory. I didn't touch the spark plugs, so I doubt there's a problem with them, but I did notice the coils didn't sanp into place smartly like I had expected. The engine really feels like it's running on about five cylinders. Are the coils supposed to snap into place on the spark plugs? Is there a trick to getting them seated properly? Thanks.

[David.X5]

The rubber boots (which can be bought separately) should "pop" on. If you aren't feeling that then I would suspect they aren't seated well. Dielectric grease can help, but it is likely there is some there already.

[Multibeemer]

Thanks; I'll definitely take a look at this, although I won't have the opportunity for a few days.

[Multibeemer]

Just to clarify, when I insert the coils into their respective spark plug holes and press down, they "bounce" back up maybe 1/8". They never actually seat onto the spark plugs. I had to rely on the tightening of the nuts to get the coils to fully seat against the heads. All eight of the coils behaved this way. I don't remember this type of behavior on any of my other BMWs. Does this sound like it could be behind my engine's rough running?

[David.X5]

The boot is separate from the coil. I attach the boot to the coil first. You should feel that click into place. I then attach the boot+coil onto the plug. You should feel that click into place. If the boots are new or newish, they seem to stand up a little and will get pushed down a little as you tighten the mounting nuts. Pay attention not to forget the electrical grounds that should go under the mounting nuts.

Hope that helps.

David

[Multibeemer]

Hmmm... I wasn't even aware the boot was separate from the coil - the boot and coil have always come out as one unit. I think I'll try removing the coil/boot assemblies, then removing the boots from the coils, reattaching them, and then pushing the boot/coil assembly back into the spark plug hole. Definitely not feeling anything click into place at this point. I wonder if the boots separated a bit from the coils as I was pulling them out. Thanks for the info.