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tek0011 11-14-2012 03:49 PM

Rough start and knocking - then fine.
Hello fellow bimmer enthusiasts.

I am having an issue (or more) with my 2001 503i.

Throughout Summer she was rough starting kind of sluggish, I have to assume something fuel related, as if shes not getting enough fuel.

If I try to drive off, its like theres no gas/acceleration. If I drove for another 2-3 mins, it was fine for as long as I drove. Then there are times where it would rough/sluggish start as it did, have the same issue with gas/acceleration, and I would drive to a gas station/coffee shop (short distance). Stop the engine, come back to it and as I put it in reverse, it would go about 5-10 feet, then the engine would die completely. I would restart it back up, and it acted like nothing was ever wrong.

Fast forward to November in MN. 23 degrees outside.
Now that rough start up has turned into a VERY rough start up accompanied by a loud knocking coming from the top (or so it seems on initial inspection) of the engine.
The knock is occasional, about every 7-15 seconds. The car goes to a very low idle and has died twice. Otherwise it keeps going but keeps knocking. If I keep it revved around 1500-2000 RPM it seems ok, but the idle does drop as it seems its not getting enough gas. I keep it revved occasionally and do this for about 5-10 mins. Which after that is absolutely fine, no idle issues, no knocking.

Until the next time I start it again....

More information?


champaign777 11-14-2012 04:11 PM

oil changes every 15k miles ?
you might have many different issues , for the knocking my bid is a sticky lifter

tek0011 11-14-2012 05:49 PM


Originally Posted by champaign777 (Post 7195331)
oil changes every 15k miles ?
you might have many different issues , for the knocking my bid is a sticky lifter

Every 10-12k. However the knocking is only on startup after the cars been off/sitting for quite some time. If I come back to the car an hour or two later, its fine. No issues on startup. Its when its been sitting for 6-7-8 hours.

champaign777 11-14-2012 06:55 PM

google "sticky lifter" "engine sluggish"
you will need to start changing oil every 3k miles or so
long way to go
+ change your gas filter and clean fuel injectors
+ read codes

tek0011 11-15-2012 07:37 AM

Yea I have to assume that the fuel pump/filter is next to replace/fix. Injectors were all replaced about 20k miles ago.

Im going to doubt the oil has anything to do with it. Being a surface analysis chemist, I work directly with motor oil companies and wont even get into how big of a rip off they are.

To add more to it, when I start it and it has its rough start, if I hit the gas pedal, its about 4-6 seconds before the engine actually revs. This change/add any other thoughts or ideas?

poolman 11-15-2012 08:14 AM

How about Vanos seals--are the ones in the car OEM?

tek0011 11-15-2012 08:25 AM

yes. and i know they were slowly going about 10k ago... good point. would the Vanos seals cause an issue with starting, but not once the car gets going?

tek0011 11-15-2012 08:34 AM

i should also mention, even though its a 2001, it has 90k miles on it.

venzon 11-15-2012 08:44 AM

Check your DISA. Same symptoms when DISA failed on my 330i.

champaign777 11-15-2012 03:52 PM

didnt see you have 2001
throttle body issue cant be related to this

"if I hit the gas pedal, its about 4-6 seconds before the engine actually revs."

tek0011 11-15-2012 07:30 PM

tyvm good sir

poolman 11-16-2012 12:23 PM

Classic Vanos sympton--cold car in cold weather--hard to crank and when the engine warms up a bit all the problems seem to go away--

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