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2002 E39 525D - Intermittent starting problem when warm - 2550 rail pressure control at start

9K views 7 replies 3 participants last post by  aeomholt 
#1 ·
I'm struggling to find the cause of the intermittent starting issues.

When cold it cranks and starts normally.
If I drive it so it reaches normal operating temperature it most likely wont start when hot, just cranking.
If I wait to the engine is cold again after leaving it over night, it will start.

INPA show this error code: 2550 rail pressure control at start

Pre pressure is approximately 3.7-3.8 bar with ignition on and doesent drop below 3.6 bar at full load.

Fuel filter is new, pre supply pump is running, a half litre coke bottle is filled in the time I use to turn on the ignition and walk to the engine bay and check it.

Any ideas?
 
#3 ·
You are absolutely right about that. I may have been to caught up in the error code.
Wouldn't the cam sensor throw a error code though?
When disconnected it throws a code.

Did take it out and it's the original one with 300000km on it :)

Did in fact have some similar intermittent starting issues on my 540i with longer and longer cranking time. Then I changed cam sensor and it fired right up every time. It did not throw any codes either.

Thanks for pointing me in that direction :)
 
#4 ·
Its an odd because it tends to throw other codes like smooth running faults which leads you off on a wild goose chase with injectors! The cam/crank sensors only throw codes when they are proper dead, either short circuit or open circuit overwise they have no other built in diagnostics
 
#5 ·
Changing the cam sensor did not help :(

Drove the engine nice and warm, parked in the garage, stopped it. Fired right up several times. Waited 5-10 minutes and it's cranking only...

Plug and contacts for the rail pressure sensor was ok, no corrosion or damage.

Crank sensor next?

I'll try to do a leak down test if I manage to feed the return line into some bottles.
 
#8 ·
I did a non scientific leak down test of the injectors by disconnecting the return lines even though its very messy.
That reviled that two out of 6 injectors are leaking like a water fall...

I guess I have had one leaking injector for quite some time due to the error code and now two that results in hard warm starts.
Replacement injectors are on its way :)

Thanks for all the reply I've got.
 
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