E39 97 540ia, Misfiring - BMW Forum

///Matt · 11-16-2004, 02:24 PM

Ok, I'm sure BillB will know the answer before i refresh the page...

Found out what is causing my "Service Engine Soon" light to come on. Codes are showing that cylinder 7 is misfiring. I was hoping this wasn't the problem, but i have noticed that the car has been running a little rough, but nothing severe. Both times that i have noticed the rough running and light have been in rainy weather...im guessing there is a connection.?.?.? Any input would be appreciated about what i could/should do....THANKS!

This time ill go for lucky 7

ghead

Dirty_Tool · 11-16-2004, 03:27 PM

If you have the capability of reading and clearing codes then id recommend doing this.....

Swap the coil from cyl #7 with another cylinder, prefferrably not 6 or 8...u want it to be a couple of cylinders down to prevent any misreadings from the emissions control system. then swap the spark plug with different cylinder. clear the fault memory and drive the car. See if the fault returns but only this time in 1 of the cylinders that u swapped the coil or spark plug to. Basically this will tell u if u have a bad coil (coils are common failures) or spark plug (not so common.)
If the fault does not move and reoccurrs still in cylinder # 7 then the only thing left would be the fuel injector on cyl # 7 or the internal cyl itself (ie burnt valve, broken ring etc)

Make any sense?

Also 1 thing to check/try bmaybe before getting in to all of this is to lift the vehicle and check the catalytic converters. Try hitting them with a rubber mallet or deadblow hammer and see if they are broken apart internally. If so then they will rattle. If thats the case then the cats could be restricted and causing the misfire. This too is another very common failure.

Hope this helps, Good luck.
DT

///Matt · 11-17-2004, 09:00 AM

Ok, so now I've probably made tings worse....

Last night i went in to check the spark plugs (im no mechanic but...) opened the drivers side panel on the engine (black plastic cover) i found a significant amount of oil (not fresh, but definitely within the last month). Would this the red flag as this is the cylinder that is misfiring? The thing that makes it worse is that i used the glove box flashlight.....now its gone...somewhere under the hood

ghead Oh well, once it melts it'll be gone lol

billB · 11-17-2004, 10:26 AM

Dear ///Matt

Not quite and trust me you are with a PRO here; Dirty Tools has been an authority in troubleshooting....DirtyTools is that good. As such I am taking the fifth on your problem!!!

P.s. I am sure you will sort it out.
regards
billb

Dirty_Tool · 11-17-2004, 11:40 PM

Thx Bill for the compliments

...hopefully I can live up to your remarks.

Cheers,

DT

Eric S. · 11-18-2004, 11:30 PM

I was initially going to suggest swapping the coil to another cylinder as DirtyTool suggested, but now that you mention removing the plastic cover and finding oil on number 7, it looks like a classic case of valve/cam cover gasket leakage that has progressed to the point that your spark plug is now beginning to get fouled in its own oil bath (the rear 2 plugs on each side get wettest first).

I know this sounds like a lot, but I think you need to replace your valve/cam cover gaskets (consider paying someone the $350 heh, heh

). Make sure the spark plugs and recesses get TOTALLY cleaned of any oil and the spark plug threads (is it time to replace the plugs too? Now's the opportunity) get coated with some fresh copper-based anti-seize. Then put it all back together and see what you get. If you still get the trouble code, the go back to the swap coil routine. I cannot confirm first hand, but my dealer parts guy told me that if you leave your plugs bathing in oil long enough, it will ruin your coil from the bad ground connection thru the spark plug.

Anyone else agree or disagree?

///Matt · 11-19-2004, 10:06 AM

Finally its all over....simplicity never usually works for me so well. For some reason the plug was very loose. I'm still trying to figure that one out...because im skeptical... BMW spent only 40 minutes (shocking i know at $100/hr) finding exactly what was wrong. I fired it up when they returned it too me...light off, and MUCH smoother running. Thanks guys! So whatever they "Really" did seemed to work.

Dirty_Tool · 11-19-2004, 12:19 PM

Hmm Good news,

Loose plugs can happen and are usually really easy to spot because of the specific noise that it makes (almost like an exhaust leak its sort of "puff puff" kinda noise.
Sounds like they treated you right. Did they check the torque on the additional 7 spark plugs for you while they were in there? If not you should do that. Its common that when 1 plug is loose enough to be causing a problem the rest are also unproperly torqued and may cause problems soon. Glad to hear the problem is solved, congrats.

DT

P.S Did they find your flashlight for you?

billB · 11-19-2004, 06:15 PM

While at this topic; what is your position on applying the anti-seize to the threads on the spark plugs. I hear many conflicting views:

A. some would argue that some brands have chemicals which under extreme conditions will contribute to the deterioration of the threads on the head itself.
B. Others will argue no harm is done to the threads when copper-based compounds are used. What is your take on this?
c. Some will go as far as saying anti seize may produce a torque multiplying effect. This can lead to thread distortion resulting in head damage.
Either way, do we know if BMW dealers use these compounds when installing spark plugs? If so, which brand/type?

regards
billb

Dirty_Tool · 11-19-2004, 11:52 PM

Bill,
While i dont personally see the anti seize causing an issue it is not mentioned in the BMW TIS repair instructions nor is it done by most dealership technicians. Doing spark plugs myself I really havent seen a lot of issues with the threads. I havent seen a lot that are corroded or have any other issues unless they were caused by misinstallation. So basically I dont use it and I dont think its necessary but if guys want to do it I dont see a problem with that.

DT

billB · 11-20-2004, 08:14 AM

DT
Many thanks

WindowPro · 11-21-2004, 03:59 PM

Awesome thread guys! Good news ///Matt.

Eric S. · 12-02-2004, 01:04 AM

Quote:

Originally posted by billB@Nov 19 2004, 08:15 PM
While at this topic; what is your position on applying the anti-seize to the threads on the spark plugs. I hear many conflicting views:

A. some would argue that some brands have chemicals which under extreme conditions will contribute to the deterioration of the threads on the head itself.
B. Others will argue no harm is done to the threads when copper-based compounds are used. What is your take on this?
c. Some will go as far as saying anti seize may produce a torque multiplying effect. This can lead to thread distortion resulting in head damage.
Either way, do we know if BMW dealers use these compounds when installing spark plugs? If so, which brand/type?

regards
billb

[snapback]234052[/snapback]

Bill - I want to point out that the Bentley Manual for E39s (the over-priced, 2-volume set) recommends using a copper-based antiseize on the spark plug threads when replacing. Further, when removing my old plugs (which were original), they seemed to have a trace of copper on them. Even so, after 100K miles, they were none too easy to break loose. (It may be the Copper-based antiseize is only needed on the 1999-and-up 540 with the 100K spark plug interval - it makes sense there might be a different treatment for those).

Just my 2 cents.