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understanding Fuel Rail Pressure and Suction Control Valve
Hi I would appreciate assistance in understanding data. From what I can see there does seem to be a spike in rail pressure even though the rpms etc remain fairly constant,
Very difficult to interpret the mass of data in pdf,you would be better to look at rail pressure through a graphing medium,if that’s possible,there is a correlation between inlet metering valve,usually done through a duty cycle set by various inputs by the pcm,ie app,air mass temperature coolant temperature etc, some rail pressures are controlled by the imv and some by a regulator,
speaking about fuel pressure only... depending on your vehicle make, fuel pressure is different from manufacturer to manufacturer... fuel pressure will increase and decrease with engine vacuum. At idle, vacuum is high and at WOT vacuum is low. The pressure regulator works off engine vacuum to supply the engine with the proper fuel pressure and fuel flow. Some vehicles have a constant pressure.
With the engine at idle, the pressure could be say, 35psi and at WOT it could be 48psi. At idle, snap the throttle to wide open then let off. Watch the fuel pressure to respond. The pressure goes up then down to just slightly below idle pressure then comes back to idle pressure.
Remove the vacuum line from the pressure regulator at idle, the pressure reading you see will be your WOT pressure.
If your getting fluctuating psi readings at idle, your fuel pressure regulator could be failing or a vacuum leak.
Are you sure the readings are correct. 59257kpa = 8594psi.. Depending where you put the decimal point that could be anywhere between 8 to 8k psi. The 292.32 would be 33.7psi.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
I beg your pardon if I was mistaken as I took the question of rail pressure from the point of view as a diesel/gdi petrol as the phrase imv , I may have misled the poster,if so I apologise.
Not to worry... we are all here to help each other...
Not up on diesel stuff... what I understand, the suction control valve is inside the rail and acts as a pressure regulator. It is subject to wear and clogging. Pressure readings can go into the thousands. I would go to the valve and check it for wear and clean it and make sure all electrical wiring and connections are good especially with fluctuating readings.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Good morning, i personally have never seen an imv on the fuel rail,usually it fitted on the high pressure fuel pump,applicabile on high pressure petrol/diesel,the imv can be used to regulate fuel in and out of the fuel rail on single point controlled pump,or as a inlet valve in conjuction with a regulator solenoid on a dual point control system.
The best way to look at fuel rail pressure is thrugh connecting directly to the rail pressure sensor using a scope or if a scope is not available through serail data through a scan tool,Dont forget that scan data is processed data.
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