Squealing brakes and Rough Idle - FIXED

Car: E39 530i 2002 Sports
Miles: 102K

Here is what happened: I heard squealing scratchy brake noise when wife drove into our driveway while I was outside. I figured something was wrong, so decided to take the car out for a spin. First thing I noticed right away was that the Check Engine Light was ON to begin with. Anyway drove around, the brakes squealed and whined while driving without even engaging the brakes, and they were loud!

After driving around, came home, sat in the car thinking what could possibly be causing this? Then noticed that the car was having rough idle. Was vibrating hard. Plugged in my diagnostics tool. It showed Error Code P1349 "Misfire Cylinder 4 with Fuel Cut-Off"

Well I thought I was planning on changing Ignition Coils and spark plugs anyway and that they may have caused that particualr rough idle issue, so went ahead and put in all the new Ignition Coils and spark plugs.

That actually didn't fix the rough idle issue and now throws a different code P1347 "Misfire Cylinder 3 with Fuel Cut-Off". Apparently the problem has moved to cylinder 3 now.

While wondering about that, I shifted my focus on the brakes, pulled the driverside microfilter housing to access the brake master cylinder and booster unit. Noticed that the well was full of leaves debris and gunk. Drain was plugged and may have been for a while. We live in the rainy city of Seattle so you can just imagine.

Anyway now I am beginning to think that the rough idle and the brakes are a related problem. Maybe the water has gotten into the brake control unit and the vacuum has sucked the water inside the manifold or something as the whole car vaccum system is shared.

I am sure someone must have had the same problem and the fix. I do not want to get into the VANOS and DISA projects yet before I rule out a few things.

Here is my sequence to trouble shoot:

1. Replace Ignition Coils and Spark Plugs [DONE]
2. Replace Brake Booster and Master Cylinder. Anyone got a video/text tutorial on that?
3. Replace the brakes. [Kinda wanna do it with new rotors and brake pads anyway]
4. If all fails (excluding #3) I will dig into CCV and DISA stuff as next steps.

So thoughts? Experiences? I searched around here but have not found a concrete answer to this possibly related problem and a sure fix.

Please share link to the thread that actualy solves this problem. I may have missed it

Any help and suggestions are greatly appreciated. Cheers!

this is a common problem. the drain tube in the cabin filter clogs leading to a brake booster sucking water. Many people have experienced catastrophic engine failure due to hydrolock.

Do not even start the car until you get the water out. You risk hydrolock blowing your motor up. You may find more info on this at bimmerforums.com as this seems to pop up about once a month there.

Thanks Topaz540i for a quick reply!

How and from where do I get the water out off? I will definitely check out the site that you mentioned.

First is to get all the gunk out of the well. Use a shop vac? Then, free up the drain.

Try to find evidence of a water line in the well. Is there water in there now?

If you plan to tackle the replacement of the master cylinder and brake booser, you need to get the Bentley manual.

edjack: Well and the drain are clean now. It's been dry lately so I didn't see any water, though the gunk and debris was all wet still. I can't see a water line in the well, don't you have to be in a stationary situation to develop those? Car moves and splashes water all the time.

Ordered the Bentley Manual now

some how the brake booster must open up. Its the huge round thing on the fire wall that the master is attached to.

UPDATE: So yesterday I put in all the new ignition coils and spark plugs and the car was still vibrating and the usual misfire code. Ran it for a while and then left it alone and started focusing on the brake problem.

So for that I accessed the master cylinder well, cleaned the debris and gunk, opened the brake reservoir cap to see for any visible water ingress etc. Then unhooked the vacuum hose that is running from the master brake cylinder to the manifold side. Started the car while plugging the vacuum hole there. Revved it for a little bit and then called it a day. This evening I started looking again and plugged the vacuum hose back. Started the car and let it warm up fully. No Misfire codes and car was running smoothly and no rough idle, even in cold start. Cleared the code and no check engine light.

Took it out for a spin around the block, drove normally and nothing, no vibrations and engine light hasn't come on yet. Brakes however are still squealing like crazy. Hooked the diagnostic tool and still no codes and car is still running fine.

I do hear a "hisss" sound in the engine as if its sucking air, not sure if that is normal? Anyway I'll keep updating as I observe things and as I change the rear brakes. Oh yes its only the rear brakes that are squealing, not the front! Can someone please confirm the "hissss" engine sound for it being normal?

I don't think the problems are over but interesting behavior.

Anyway, just an update. Comments welcomed

UPDATE: The long and short of it is that all systems are a go!

This is what I did, and thanks edjack for mentioning Bentley Repair Manual. Here is the sequence:

1. Cleaned all brake pads and rotors.
2. Removed, cleaned and re-installed the same Brake Booster. There were minor signs of moisture in there, cleaned and dried it with care before re-installing it.
3. Replaced the Vacuum Hose from Brake Booster to intake manifold with new screw type clips.
4. Cleaned the brake booster well and made sure drain is open. Well looks new now
5. Flushed brake fluid, added new fluid as per manual and bled all the brakes. Seems like the fluid had water in line. Flushed fluid when placed over night had a water and "oil" separation clearly visible. Accidental discovery BTW!
6. New ignition coils and spark plugs were already replaced in first trouble shooting step.

At this point the car is running like new. No brake squeals and locked rear brakes anymore. No more Misfires and no check engine light anymore. Diagnostics tool shows no more errors.

Drove the car about 100 miles on freeway and in city and she is happy as she could be! Thanks everyone for your help.

Now I am left with a used set of six ignition coils that are apparently still good. But glad that I replaced them anyway. If anyone wants 'em, let me know. They are yours.

Cheers!

Glad to hear your cars doing well now that you found the problem over in the BB well--in the below link are a number of other spots you might want to check into for possible vac leaks--these are spots that will cause problems and it's best to head them off before hand. Concerning the hose going into the brake booster--does the check valve just pull out of the booster--or did you cut the hose from the check valve and then replace it? That is one of the last lines I haven't replaced as of yet...

http://www.bimmerfest.com/forums/sho...eaks+revisited

Thanks poolman, I'll Check out the link.

I just pulled the hose from the booster check valve and not the valve itself. Didn't have to cut it. Little side turns and a strong pull will snap it off.