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7 Series - E65 / E66 (2002 - 2008)
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  #1  
Old 03-28-2013, 06:11 PM
chowdarygm chowdarygm is offline
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Location: Dusseldorf, Germany
 
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Mein Auto: BMW 318i E46, 735i E65
misfires after dis and re-connecting battery

last week while working on C pillar, disconnected the battery before which did some testing using DIS

DIS testing lasted around 30 minutes and after that worked on C Pillar for around 30 minutes.

after re-connecting the battery and starting the car, it started with huge shake and its vibrating very badly for first 1 hour ride after which it smoothens out and rides normal

everyday morning this repeats and check engine lights glow whenever i accelerate hard

INPA shows fault codes with misfires in Cylinder 1 and cylinder 7

can this be due to a bad battery ?

if not why does the engine becomes smoother after 1 hour drive ?

plzzz....i am hating to start my E65 and dont want to use my E46 due to my bad knee
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  #2  
Old 03-28-2013, 08:00 PM
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Ltmax Ltmax is offline
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Mein Auto: 07 750i, 02 540i Sport
I'd look at the plugs first (re-gap them if they are in good shape). As the engine gets hot the gap get's a little tighter and they may actually start to fire while they won't when cold. If the gaps are ok, it's most likely that you've got a few weak coil on plug units. If you tighten up the gaps to minimum and the misfire goes away that's a pretty good indicator.

The coil packs are very cheap to replace and the integrated boots at the bottom do tend to break down over time.

I wouldn't waste the money buying genuine BMW ones at the parts counter, when you can order OEM equivalent ones on line for much less. (approx $30 each)

It's really not a great idea to drive around for long periods of time with random or multiple misfires though as it's a good way to burn up your catalytic converters if your constantly supplying them with unburnt fuel they are going to run way too hot and it's going to eventually melt the substrate material inside and that's not a cheap repair.

Last edited by Ltmax; 03-28-2013 at 08:01 PM.
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Old 03-28-2013, 08:14 PM
chowdarygm chowdarygm is offline
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Location: Dusseldorf, Germany
 
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Mein Auto: BMW 318i E46, 735i E65
Quote:
Originally Posted by Ltmax View Post
I'd look at the plugs first (re-gap them if they are in good shape). As the engine gets hot the gap get's a little tighter and they may actually start to fire while they won't when cold. If the gaps are ok, it's most likely that you've got a few weak coil on plug units. If you tighten up the gaps to minimum and the misfire goes away that's a pretty good indicator.

The coil packs are very cheap to replace and the integrated boots at the bottom do tend to break down over time.

I wouldn't waste the money buying genuine BMW ones at the parts counter, when you can order OEM equivalent ones on line for much less. (approx $30 each)

It's really not a great idea to drive around for long periods of time with random or multiple misfires though as it's a good way to burn up your catalytic converters if your constantly supplying them with unburnt fuel they are going to run way too hot and it's going to eventually melt the substrate material inside and that's not a cheap repair.
thank you so much...i remember now my local bmw specialist also mentioned about coils and wants to try replacing cylinder 1 and 7 coils next week as its easter now....

is this something i can quickly do (tighten / replace) myself without big tools? (i don't have a garage ) ?

edit: nevermind...did some google and youtube..looks like i can check coils self...will check with my friend if he has the socket for sparks....will post what happens tomorrow

Last edited by chowdarygm; 03-28-2013 at 08:52 PM.
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Old 03-28-2013, 09:27 PM
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Ltmax Ltmax is offline
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Mein Auto: 07 750i, 02 540i Sport
Swapping out a full set of coils on a 7 Series only takes about 15 minutes and no special tools required. Only one small screw is holding the little plastic covers on each pair of plugs, the wiring connector just pulls off, and the coil pack slides right out with a little tug.

Doing two should take all of 5 minutes.
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