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misfires 1thru 6

3K views 17 replies 5 participants last post by  Medicus 
#1 ·
i have a 2005 bmw 645, wt 99000 miles, i do have an oil leak coming from right and left valve cover but all of a sudden engine light came on and i have a code of mis fires in cylinders 1 thru 6, and runs real rough and lose of power. I hate to replace 6 coils or all eight and not be it, any suggestions what else to look for? and what are the cannisters on top of motor it has 2 one on each side of valve, do they have any thing to do with ignition coils, I did replace all spark plugs, and no change.
 
#2 ·
If you are having that many misfires, it sounds like a fuel issue. I would suggest to change the fuel filter, then see what happens. If you have access to a fuel pressure gauge, I would check the fuel pressure before & after the filter change. The next item of course would be the fuel pump.

The 2 canisters on each side of the engine are the Valvetronic Motors, for setting the timing of the valve train.

When did all of trouble's start? Did you possibly get some bad fuel? Did you mess with anything on the motor before all of these problems started? One easy thing to check would be to make sure that the oil filler cap is on securely. A bad vacuum leak can cause the motors to run terrible.

Good Luck!
 
#4 ·
thanks for your replies, no i had not messed with anything, everything was running fine the only thing that changed was when we had a cold front, coldest it got at night was maybe 38. it didnt like the change and in the morning start it would idle rough, shaky. once it warmed up and on the after work drive it would run fine, but all of a sudden it felt like someone pulled a hose or a plug, and its like driving a 4 cylinder. about a week after the cold front. I did pull a couple coils to see if there was a change, but did not notice a difference. did you replace the exhaust cam sensor yourself, is it accessible. but it sure seems like a bad vacuum leak of some sort, where else could i check for vacuum issues with out pulling the motor apart. thanks guys
 
#5 · (Edited)
If these hose on the link have cracks, it will cause the idle to be very bad. If the engine runs better when up to speed, it suggest a vacuum leak. Inspect theses hose very carefully, because they cost around 55.00 each. They become very brittle over time. There have been several revisions to the hoses, changing from item one, to items 2 & 3. I would also go ahead & change the fuel filter.

Good Luck!

http://www.realoem.com/bmw/showparts.do?model=EH73&mospid=47767&btnr=11_3259&hg=11&fg=15
 
#8 ·
well guys i broke down and dropped my car off at a local shop, to have a full diagnostic scan, originally quote of 98 bucks, they ran a smoke test for vacuum leaks, all was good, had mis fire of 1thru 7 this time, they went thru each coil and found only one yes one!! that was shorting out and causing all the mis fires, so i had a bad coil #3 which had I known that I would of replaced all coils, so all in all came out paying 200 bucks.. which i was upset because i was right there when i replaced my plugs, but great full that it wasnt a thousand dollar repair.. and now she purrs like a kitty, so thanks for all your tips i will keep in mind for future and if anyone has a similar issue, go ahead and replace coils
 
#12 ·
yea not too bad, so here i am again on my off day tracing down a couple oil leaks, it appeared before that it looked like it was coming from valve covers but it seems to be puddling up more to the left side, i replaced a bad oil sending switch 6 months ago, i pulled plug today and theres sign of oil in plug, i guess it needs replacing again, also i pulled the plugs from underneath oil cap slightly to the right, those plugs as well had sign of oil, what are these switches called they have a bracket holding them in place as well.
 
#14 ·
Best thing to do is clean all the oil and pour some UV dye in the oil and use a UV light to see where the oil is coming from. I don't think your oil sending switch is bad again. Might just be your Vacuum unit right above dripping on the sending unit. The seals usually go at the same time.
The plugs you describe are either cam sensors or vanos but I doubt they are leaking. It's probably dripping down on the wires and makes it look like the sensor is leaking.
 
#13 ·
If you are finding oil on the top parts of your plugs, the valve cover spark plug O-rings are bad. You should replace the valve cover, & timing cover gaskets, along with the spark plug o-ring/seals. Change any seals & O-rings on the valve cover for any other sensor also. This should take care of most of your problems. The only other leak would be to check just above your driver side motor mount, to see if your alternator O-ring is leaking.

Good Luck!
 
#15 ·
vacuum pump bottom hose

I just noticed at the bottom of the vacuum pump up front does not have a hose connected to bottom, is there suppose to be a hose there and what does it serve, i looked at a diagram online and saw there is a small black tubing connected to that bottom port. thanks for any help,
 
#16 ·
I just noticed at the bottom of the vacuum pump up front does not have a hose connected to bottom, is there suppose to be a hose there and what does it serve, i looked at a diagram online and saw there is a small black tubing connected to that bottom port. thanks for any help,
If I'm not mistaken that is a test port to hook up a gauge and test the vacuum. It should have a rubber cover-cap on it. It can easily fall off if touched during servicing or checking things out. Hope that helps.

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