You need to give a lot more detail to get the help you need (see read before posting at top of forum) It sounds a poor fault description, but I would say it relates to a 3 rd piston cut off solonoid / circuit on the high pressure pump. oddly I can't see that on the wiring diagram, what EDC system number is this? You will need to check wiring back to ECU, these suffer from corroded pins on the ECU.
HI Paul, you are talking about two different components, The IMV is an Inlet Metering Valve. The DRV is a pressure regulating valve. Both of these control the rail pressure in their own way.
The 3rd piston valve is a control system that allows one of the three pistons in a Bosch CP1 pump to "free wheel" and can be used in cruise conditions. It does not control nor affect the rail pressure. HTH
Regards MarkModern cars, Its all wizardry and witchcraft
That is a terrible post & one that would normally attract some serious flack, although I sense that most old hands are tiring of banging their heads agains the ever present wall.
You seriously should consider some training if you are entering into this type of work, or at least some personal research. There is a lot of good information out there & you only need to devote your time, if you want to gain some understanding.
In the mean time....
I found this passage from an old post I made on the subject. The vehicle I am describing is a Fiat Scudo with a Bosch system, the principle of operation would likely be the same.
Old post..... (Sorry about the size of the images)
It was suggested on another forum, that it was possible to see a poorly performing pumping element in the high pressure pump, by scoping the rail pressure sensor. I thought it may be interesting to look at the effect of the 3rd piston deactivation solenoid when it is in both states.
Here is a capture taken whilst the engine was at approximately 1500 rpm, whilst I was connecting & disconnecting the 3rd piston solenoid multiplug……
I had an understanding that the 3rd piton shut off, was a feature that is used to reduce the load on the engine during times when lower fuel demands are required. It soon became apparent that at idle, all three elements were used & as the engine speed increases the 3rd piston is decompressed.
This next animation displays what I am trying to explain a little better.....
Sorry, mis-read original post (completely ignored bit about 3rd piston cut out!) we change so many pwm switches that brain fade occured - post edited to avoid confusion (mine included!)
on September 22, 2010, 9:21 pm, in reply to "
