Gadget73:
I don't have a vacuum gauge but I can tell the duty cycle of the solenoid valve does cuase more and less vacuum.
Poor man's test #1
-------------------
Engine running at revs (EGR part open).
Pulled vacuum tube off the EGR valve and quickly stuck my finger on the end of the vacuum tube. Could feel the (fast) pulses of the solenoid valve getting stronger and stronger while watching the pulse widths grow longer and longer as the computer tried to get the EGR valve to re-open.
Poor man's test #2
-------------------
Engine running at revs (EGR part open).
Pulled vacuum tube off EGR valve.
See pulses get wider - eventually going to 100%
Put tube back on EGR.
See pulses quickly wind back to 0% (as valve opens , then overshoots a bit I guess as vacuum was at 'max')
See pulses widen out again to around 30% duty cycle.
So - this says the vacuum was indeed changing on command from the computer - and the computer could get the EGR valve into the position it wanted.
I don't have a vacuum gauge but I can tell the duty cycle of the solenoid valve does cuase more and less vacuum.
Poor man's test #1
-------------------
Engine running at revs (EGR part open).
Pulled vacuum tube off the EGR valve and quickly stuck my finger on the end of the vacuum tube. Could feel the (fast) pulses of the solenoid valve getting stronger and stronger while watching the pulse widths grow longer and longer as the computer tried to get the EGR valve to re-open.
Poor man's test #2
-------------------
Engine running at revs (EGR part open).
Pulled vacuum tube off EGR valve.
See pulses get wider - eventually going to 100%
Put tube back on EGR.
See pulses quickly wind back to 0% (as valve opens , then overshoots a bit I guess as vacuum was at 'max')
See pulses widen out again to around 30% duty cycle.
So - this says the vacuum was indeed changing on command from the computer - and the computer could get the EGR valve into the position it wanted.
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