jochen 4 Report post Posted October 2, 2006 Well for those that have been here over the last few weeks might have seen me telling my woeful story of a misfire (at idle only) on my E39 540i which was becoming hard to track down. Coils, they said at BM Workshop. "We replace lots of them, they always fail" The E39 has 8 x coils, one per plug, and they are mounted right on top of the plug. They are under high-voltage stress, and also heat stress - the engine runs at 108 degrees. A tough environment for anything electric or electronic. But which coil was failling? "Wait till it throws a fault code" they said. So I waited, and waited, and went in for a fault code readout every couple of weeks. Well, the misfire slowly got worse, until it became a right pain in the idle. Embarrassing. How could I let my car stay in this state? But narry a fault code was ever logged - the misfire was too quick and too intermittent. The man from BM kindly said 'Let's do a smooth-running test' So we hooked up the DIS, and ran the test, which monitors the adaptation values (fuel-air mix etc) of each and every cylinder in real time. Cylinders 6, 3 and 7 were slightly higher than the others, but still within spec. We cleared the adaptation values, forcing the DME to re-learn the motor characteristics. Then - blip - a misfire, and at the same time the value for cylinder #6 sprang up high. Ah hah! we both said. Aloud. Quick as a German fox, out came the coil from #6, and we swapped it with #1 (after having numbered all coils of course) Drive it for a day then come back, said the man from BM Workshop I did, the misfires kept happening, so back onto another smooth-running test first thing in the morning. This time, within a minute, we caught another misfire, and it was logged on #1 "Told ya - a coil" he said. And he was right A new coil fitted to #1, and now my V8 runs very smoothly at idle, and hasn't misfired once since last Friday I'm a very happy puppy again :-). Jochen Quote Share this post Link to post Share on other sites
320SHKBTE 0 Report post Posted October 2, 2006 Good work! lol, love your storys, always a good read! Quote Share this post Link to post Share on other sites
isis 16 Report post Posted October 3, 2006 good thing you had to replace just one, i had to replace all 6 before! Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted October 3, 2006 6? Your motor must be missing two cylinders! Mine has the full complement of 8 :-) Quote Share this post Link to post Share on other sites
BMW POWER 2 Report post Posted October 4, 2006 Always love the stories. Legend. Glad you got it fixed though. Quote Share this post Link to post Share on other sites
mak1e 0 Report post Posted July 9, 2008 Hi there, how did you go with your other coils since? I have a 1998 520i, and had it scanned in a garage shop, and told me that coil #1 is not working and showing "Fault" on the scanner(which also cost me 75$) . I'm from Auckland and a coil cost 265$ each without the 20mins. labor, I was thinking maybe it'd be cheaper getting it abroad including shipment from a dealer for a cheaper price. Also thinking of replacing the coil myself. Please help anyone, thanks Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted July 9, 2008 (edited) Hi there, how did you go with your other coils since? I have a 1998 520i, and had it scanned in a garage shop, and told me that coil #1 is not working and showing "Fault" on the scanner(which also cost me 75$) . I'm from Auckland and a coil cost 265$ each without the 20mins. labor, I was thinking maybe it'd be cheaper getting it abroad including shipment from a dealer for a cheaper price. Also thinking of replacing the coil myself. Please help anyone, thanks No problems with any other coils since. As you know what coil is faulty, get a replacement (new!) coil from your source of preference, and fit yourself. Easy job to fit. Edited July 9, 2008 by jochen Quote Share this post Link to post Share on other sites
kiwi535 538 Report post Posted July 9, 2008 No problems with any other coils since. As you know what coil is faulty, get a replacement (new!) coil from your source of preference, and fit yourself. Easy job to fit. and if a misfire is logged on cylinders 1-4,would you still suspect coils,no mention of coil in faults Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted July 9, 2008 and if a misfire is logged on cylinders 1-4,would you still suspect coils,no mention of coil in faults On the V8, misfires can only be one of 3 things (in order of probability) 1. coils 2. clogged cats 3. O2 sensors If you have misfires logged on more than one cylinder, place the cat at the top of the suspect list. Quote Share this post Link to post Share on other sites
