Hi there I have a Fabia Vrs 2005 just wondered what the fuel cut off point is and what is the standard boost of my car. Any help would be much appreciated thanks.... Ben

I presume you mean the over-run cutoff. If so, then it triggers whenever you have a closed throttle and revs over 1200. Once it's cut in, it stays in until about 1000.

there is no over-run cut off on a diesel engine folks, there is always a base-line amount of fuel being pumped in on the pd engines regardless of what the ecu is doing.

there is not a standard boost level per se, it is dynamically controlled via a little bleed-off valve called the N75 valve which attempts to modulate the pressure to whatever the mapped boost pressure is based on a few factors like rpm, mass air flow, coolant temp etc etc also the boost pressure is not constant, it peaks then levels out

but it's roughly 135kpa (relative) on a pd130 engine

That may be true of a PD, but if so that's unusual for a diesel with a cut-off.

diesels dont have a fuel cut off ken, even on old school rotary injection pumps, the only device they have is to limit the maximum fuel delivery which effectively limits the rpm of the engine... the fuel stop solnoid is there to switch off the fuel supply to the pump when you want to switch the engine off and that's exactly what would happen if the fuel cut off!! it would stop!!

This just doesn't make sense to me. Why would the crankshaft stop turning just because you're not injecting fuel? Why wouldn't the engine start burning fuel again when you open the throttle, presuming the crank is rotating?

don't know much about the common rail ones sorry,

ok if the injection pump suddenly stopped pumping you would get air trapped in the fuel delivery lines which would mean you need to re-prime the pump every time you went onto over-run..

ignore what the momentary consumption meter on the dash is telling you. if you are desperate to prove it either way you could plug an oscilloscope onto the needle lift sensor on the number 1 diesel injector and watch the voltage jumping up and down and the injector opens and closes

yeah that's right what seat have told you, the N146 valve winds down the fuel delivery rate to zero demand, but as i said earlier there is still a baseline amount of fueling even on over-run, remember most of the diesels use twin stage injectors, the first stage operates at a relatively low pressure compared to the second stage main fuel jet