530i V8 starting issue

[Fabien.R]

Hi Bimmers,
It is the first Time on this forum and i am happy to share info with you, today I have a starting problem I explain on my M60B30, since about 8 month that did that to me:

- when cold it takes a little time to start up (7-8secs or tow Times) the first time of all days, but not the others tried in the day when cold
- And cold after the first start it starts quarter-turn
- hot it takes 2 sec instead of the quarter turn even if I just cut it
- and since about 1-2 month it is even worst and the idle is a litlle bit rough After start cold

- I know my pressure is good (3,5bar with a mano)
- I passed my injectors, to ultrasound
- I have an walbro pump
-new camshaft ans crankshaft sensors
-new sparkplug (iridium)
-Compression around 12 bars
-All new intake manifold gaskets ans injector gasket
-New battery
-I connect my Delphi ds150e and my maf seems to be good with 32kg/h when cold
-My idle regulator is not stuck and we can hear it running


I've been looking for months but can't find any ideas?

Thank you in advance

[shogun]

Moved to E34 forum

[moroza]

Did you measure fuel pressure right before a cold start? The pump may be healthy, but the check valve may be letting pressure off when the car sits for a while. This is a common problem.

[Fabien.R]

Hi, yes i check and when i turn the Key pressure go up to 3.4 bar aproximatly

[polov8]

3.4 before you've tried cranking?

[Fabien.R]

Yes, juste when i first turn the Key without cranking

[moroza]

Fuel pressure is at 3.4 bar at the same time as the engine cranks without firing? That's strange... I'm not sure what could cause that, so I suggest general-purpose diagnosis: smoke test for intake leaks, normal hot compression test, and in this case a special cold dry compression test (not normally done): let the engine sit a day or two, remove all sparkplugs, disconnect the ECU (easiest way to stop the injectors from firing), and check compression on all cylinders. Record results, then repeat the test with a little (5-10ml) oil in each cylinder. Report back.