[Pauljvincent]

I have a 2006 325xi a month back I had a slow crank charged the battery a couple times and then replaced it. I still had a slow crank but it started and ran well. Then cold snap had to boost the battery it ran a whole day no issues. Next day it ran for about 15 seconds and shut off. Now it cranks not super slow but not great. I checked the battery, good. Checked the connections, good. Checked the fuel pump pressure, voltage, ground, and volume, good. Replaced plugs, checked spark, checked vacume and leaks, all good. Checked IBS, good. Checked fuses and relays, good. So things I’ve noticed on full battery and a booster on no improvement in cranking speed. It is unlikely it’s the timing because it had this issue and ran but then quit. The cylinder compression is appears good but my compression meter is of so so quality. On the new plug I can see the spark contact marks so there’s spark. I’m confused what I’m missing all help is appreciated.

[bluewater328]

I mean, you checked everything except the starter.

[F31B48]

Did you check engine earth cables?

[gbalthrop]

As EvaBMW says, a failing GROUND Cable between the Chassis & Engine, near Starter, COULD cause BOTH, engine to die while running, AND slow Starter Cranking.

You don't have to get under vehicle, remove splash shield, or replace anything to test if THAT is the issue. Simply open hood, connect ONE end of a Jumper Cable between the Chassis Ground "Hex-Pin" on the Right Wing/Fender, and the OTHER end to the engine block or large bolt/bracket connected to Engine. The Jumper Cable is acting as a "Supplemental Ground Cable".

Now try cranking the Starter and see if Starter RPM is GREATER than it was before. IF it is, then if your engine does NOT now start & Run, the lack of proper Ground when the engine last ran (and died) caused a blown fuse or other electrical issue due to "Over-voltage" when the engine last ran, and THAT problem must be identified & corrected to get the engine to run NOW.

ANY Scan Tool that can read Fault Codes saved in DME (Engine Control Module) Fault Memory would provide CLUES (Fault Codes and/or "Freeze Frame Data") to assist in Fault Identification.

George

[Pauljvincent]

Ok thanks I did the ground test no change. I checked the cables. George I also checked fuses but did finally get a code for the thermostat low voltage. I have removed the vanos and tested them now as well. Is there an easy way to test the injection pulse?

[Pauljvincent]

How do I test the vanos for function as well.