Occasional 525i M50 Engine Misfire Problem – Solved

[stilljester]

Well I can't say I've ever seen this happen before….

In the past few months I had several issues with the car running a bit rough off and on. It seems there was no pattern to it at the time but looking back no it normally followed rain. A majority of the time it would run rough then after 30 min smooth out no problem. Last week it started again and unlike before the "rough running" wouldn't stop. I thought it was most likely the coil packs since they had 200k on them. I was more or less correct.

I first tested to make sure the coil packs were receiving power - Sure enough 12v.

Next I checked the resistance on each pack - All tested in range between 0.4 - 0.8 ohms. I then noticed a bit of rust underneath the coil pack closest to the firewall.

As I went to remove the coil pack it acted stuck. I gave it a good tug & the bottom of the boot immediately broke and pulled off revealing.... ICE!?!?!

http://images20.fotki.com/v380/photos/9/925706/4521563/CIMG0115-vi.jpg

Once I removed all of the ice/water and replaced the boot the car is back to its old self. (Running Great) I’m reasoning water was seeping in after rain storms & shorting out the dry rotted plug boot. The car would then start running rough - after some time the water would evaporate off and a normal idle would return making diagnosis difficult. Luckily this past week the weather had been cold creating ice otherwise I may have never noticed it.

Just thought I put this out there incase someone else was having a similar issue.

[Jon K]

is that #5?

If so, I can tell you where it's coming from.

I have my #5 plug hole fill with water even with the engine cover on. The engine cover has two mount points covered with decorative caps - the windshield washer nozzles are conveniently over the #5 area. If you dn't have an under hood mat or have one that leaks, the water will puddle RIGHT on top of that cap and drip down into the #5 plug hole. I filled my engine covers rear hole up with silicone and only use the front mount.

[ryan roopnarine]

florida car owner here, my number 5 and or 6 fill up with water, like clockwork, once every six months or so. i chocked it up to missing a trim piece before this thread. i parked the car for a month in august (it was raining every day). by the time i got back, every single plug hole had a FULL quantity of water. it was a good thing that i had a hunch about checking them before starting it. i'll usually be driving along, pass over a long sweeper of a curve, and the car will start bucking and studdering. i sigh, turn around, go home, and break out the q-tips, crc contact cleaner, and the 10mm tube wrench and the spark plug tool from the trunk tool kit--and within 30 minutes, i'm good to go for a couple more months.

[Jon K]

florida car owner here, my number 5 and or 6 fill up with water, like clockwork, once every six months or so. i chocked it up to missing a trim piece before this thread. i parked the car for a month in august (it was raining every day). by the time i got back, every single plug hole had a FULL quantity of water. it was a good thing that i had a hunch about checking them before starting it. i'll usually be driving along, pass over a long sweeper of a curve, and the car will start bucking and studdering. i sigh, turn around, go home, and break out the q-tips, crc contact cleaner, and the 10mm tube wrench and the spark plug tool from the trunk tool kit--and within 30 minutes, i'm good to go for a couple more months.


Ryan - try pulling down your hood insulation and using clear RTV to seal around the windshield washer sprayers. Careful not to get silicone popping out and onto the hood surface, but you get the idea. I found this is where my water was dripping through. I used to not use the engine cover and would fill the #6 up. Then I put the cover on thinking water got up there while driving (which is untrue) and surprise the #5 hole filled up. I placed cotton balls around the engine bay and came out the next day. The one under #5 was wet. Lifted the decorative nut cover and there was a droplet of water in there. Bitch drips down through the windshield washer thinger, onto the cover, into the cavity, down the bolt hole, and into the spark plug hole.