Electrovalves equal pressure?

[c.morewood]

Should both electrovalves operate at the same pressure?
I was experimenting with removing the vaccum pipe from the EGR valve to try to cure a lack of power and apparent stuttering or reluctance to accelerate past 280RPM under load.
This resulted in the expected engine management light, but not for 120 miles after thye pipe was removed, which was surprising.
In the process I removed all the vaccum pipes and checked they were clear. But noticed that the vaccum on the front electrovalve was much stronger than that of the rearmost one which was quite weak. Is this correct or should they be the same suction?
Thanks,
Chris

[cachaciero]

Not clear to me if the O/P is looking at the vacuum inlet to the EV or the Output of the EV.
I would expect the inlet vacuum to be the same, as far as I am aware there are not two vac sources on the 2L unlike the 2.2.
The outlets are a different matter, the EV switches the outlet between atmosphere and vacuum having switched it takes sometime for the output to change from full vac to full atmos depending upon the volume of the device it's driving. Now imagine that you could drive the coil rapidly between full on and full off if the on time and off time were equal then the output pressure would be about half way between atmospheric pressure say 1013 mB and max vac pressure say 200mB so about 406mB if you now change the ratio of the on to off signal then you will effectively be able to change the pressure over a range of 200mB to 1013mB depending ,on the on/off signal ratio, sometimes called the mark space ratio. This is the technique which is used by the ECU to drive the valves proportionally on S1 cars, S2's got a little more sophisticated
So if you are looking at the o/p of the valve the vacuum you will see is what the ECU thinks it should be, which should be the amount of vacuum required to drive the actuator on the end to the desired control position. if there is a problem with the EV the vacuum level may not be what the ECU thinks it is but it has no direct way of knowing this. On S2 cars most of the actuators have feedback pots which the ECU can read to check the actuator position is correct i.e closed loop this is true of both EGR and Turbo Geometry actuators.

cachaciero