1992 Volvo 940 Turbo 'crapping out"
#42
thhis is a turbo? so you have a boost gauge. what is it doing when you rev it in neutral vs rev it in gear ? idling, there should be a vacuum, eg, the gauge is maybe 30 deg to the left of 0. when you step on the gas the vacuum should go to zero, and as the exhaust pressure builds up, the turbo kicks in and you shoudl have positive pressure, eg maybe as much as 30 degrees to the right of 0.
you should do a fuel pressure test. with the vacuum line disconnected from the fuel pressure regulator, the fuel pressure should be 42-44 PSI, constant whether you're idling or revving up. with the vacuum line connected, it should drop by the idle manifold pressure, which is maybe -7 PSI so you'd see 36 PSI fuel pressure. if you give it gas, that will rise, if the turbo is working to get actual turbo boost you'd see more than 42-44 PSI (but thats unlikely without an engine load).
you should do a fuel pressure test. with the vacuum line disconnected from the fuel pressure regulator, the fuel pressure should be 42-44 PSI, constant whether you're idling or revving up. with the vacuum line connected, it should drop by the idle manifold pressure, which is maybe -7 PSI so you'd see 36 PSI fuel pressure. if you give it gas, that will rise, if the turbo is working to get actual turbo boost you'd see more than 42-44 PSI (but thats unlikely without an engine load).
#43
#46
#47
It acts like the problem is the Idle Control Sensor input to the CPU (which is nothing more than a micro switch) When you put the transmission in drive and barely move the Idle Control Sensor to where the micro switch barely clicks...the engine dies ! BUT NOT IN PARK OR NEUTRAL ??? PS: the Idle Control Sensor has been changed !
#48
when the idle switch is closed, the ECU regulates the idle speed by modulating bypass air via the idle air controller (IAC). there's a procedure for adjusting this, see https://www.volvoclub.org.uk/faq/Eng...itchAdjustment
#49
#50
the throttle idle switch goes to ground, and is connected via a orange wire to pin 2 of the ECU, and also to pin 7 of the ICU. inside the ICU/ECU should be a 'pullup' resistor, so if the switch is open, the input is some voltage above zero (don't know, don't care), and if the switch is closed, it will be 0 volts.
ecu pin 3 is the full throttle switch (red-white wire).
ecu pin 3 is the full throttle switch (red-white wire).
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