Recently, my car had trouble starting in the morning or after a long sit. Turned out that it was a bad fuel pump relay. All was well, until recently. I've been getting a different start up issue. First, the car takes, more like requires, a minimum of three start up tries to get it going. The original crankings end with a very quick start up jerk (only way I can describe it) and quickly die, or the car just cranks with no start up progress even after I release the key. When the car does eventually start up, it sputters for a second and then a cloud of smoke comes from the tail pipe. This is the only time the car smokes or for that matter has ever smoked. It emits nothing at all when driving…all clear exhaust. This also only occurs on cold start ups. The car has problem-free warm start ups.
And one last thing, sometimes when the car starts up after the third or so try, it doesn’t burst up in idle; it just slowly makes its way up to 900 rpms at most and tapers down to 700.

Now after all of this occurs, the car runs perfectly except for the "new" knocking noise. This noise only comes ever so often, maybe every other drive. Once it starts, it stays with the car the entire lenght of the drive. It’s a much louder and more pronounced knocking, not the usual quiet tapping of the injectors firing. But, when I shut the car down after a drive and start it back up, the noise is gone and cannot be heard. I haven’t been able to listen and track it down because it is only loud enough after I drive for a few minutes. Sounds like someone taking a small hammer and knocking the top of the engine with it.

Any possible answers to either problem?
--
-Brandon at FSU '88 744ti 150k miles