Hello , good therory but incorrect Erubus , if I'm correct I think this is cp3 with inlet metering valve on the pump ?? The pump is capable of making max pressure ( around 1400 bar ) at idle speeds or less , if you ' dead head ' the pump it will make max pressure just cranking .... dead heading the pump is removing inlet metering valve and fitting a blank in its place that leaves the pump fully open to make max pressure , its a test you can do as a proving test for the pump , main control of high pressure is done by inlet metering valve .
On cp3 ....again from memory injection commence starts at 250 bar .....so injectors do no start to trigger till rail pressure is at 250 bar or thereabouts , but non of this happens until ecm sees crank and cam synchronisity .
Where you say you saw 90 bar of pressure and it started may not be accurate , whilst under cranking ecm obd data can be notoriously in accurate , I would be scoping rail pressure sensor voltage for more accurate reading , you could do it with a voltage meter , just scope traces show a bigger picture .
In the data blocks can you see a block that says .....synchronised...yes / no , this is a very important factor ....with out this the whole start sequence will not happen .
At idle ,stationary ,when warm tell me the rail pressure and tell me the duty cylcle of the inlet metering valve , whilst driving on the road with vcds ( better take a passenger or log it ) put foot to the floor and at max acceleration look at fuel pressure and inlet metering valve duty cycle .
When the car does it's non start thing ...if you give it a touch of easy start does it burst into life and instantly runs as normal ?
Does th car have the electric fuel pump in the tank ....can you hear it prime on ignition on
A few things to have a go at for now
I'm a diagnostic tech ...this is what I do everyday , stay focused on individual tests ....... test ....rule out .....move on to next test
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