The electrical connector to the IACV
can have 2 or 4 pins:-
2
pins: resistance between pins should about 10 OHMS +/- 3 OHMS. Resistance between either of the pins and the
valve body is greater than 10,000 OHMS
4
pins: resistance between diagonally positioned pins should be about 20 OHMS
How to fix? If
the motor of the IACV has failed then replace it. If the valve is gummed
closed by baked oil and carbon then clean it thoroughly with carburetor choke
cleaner spray and a cloth. Similarly if the entry and exit ports on the
throttle body to the IACV look blocked again clean them out thoroughly
3) Throttle Position Sensor TPS - How to check?
The socket for electrical connection with the TPS has 3 pins, one for
'ground', one for 5 volts 'reference' and a third (generally the middle one)
for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to
the probe and measure the voltage output as the throttle plate is rotated. If
working correctly the meter should show a voltage consistent with the throttle
position from approximately 1 volt when closed and 5 volts when fully open.
What is looked for is smooth
voltage increase with throttle change.
If there are drop outs in the transition or that there is no transition seen
the TPS is faulty.
How to fix? If the track is dirty
causing drop outs, try cleaning it with residue-free electrical cleaning spray.
If the track is worn it is perhaps easiest to replace the complete device.
In some instances it may be possible to adjust the location of the central
mount of the TPS contact arm along the throttle shaft by a few millimeters and
in the process cause a fresh concentric region of
4) Fuel pressure regulator _ Yes I know you have checked it for pressure but at start up when the ignition is at position 2 the fuel pump starts up and pressurizes the fuel rail. As you turn to position 3 "ignition" power is cut to the pump and fuel pressure is maintained by a non-return valve in the pump. If that valve is faulty the fuel pressure in the rail will drop to zero just when you need it and no fuel can be injected. Check the fuel pressure when at position 2 and then switched off; fuel pressure should be maintained for up to 5 minutes with little or no loss. If there is pressure loss then either the non-return valve is faulty or you have leak in the fuel pressure regulator. If it is such a leak, fuel will dribble from the vacuum line connected to it when disconnected.
The electrical connector to the IACV
can have 2 or 4 pins:-
2
pins: resistance between pins should about 10 OHMS +/- 3 OHMS. Resistance between either of the pins and the
valve body is greater than 10,000 OHMS
4
pins: resistance between diagonally positioned pins should be about 20 OHMS
How to fix? If the motor of the IACV has failed
then replace it. If the valve is gummed closed by baked
oil and carbon then clean it thoroughly with carburetor choke cleaner spray and
a cloth. Similarly if the entry and exit ports on the throttle body to the IACV
look blocked again clean them out thoroughly.
2) Throttle position sensor - How to check?
The socket for electrical connection with the TPS has 3 pins, one for
'ground', one for 5 volts 'reference' and a third (generally the middle one)
for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to
the probe and measure the voltage output as the throttle plate is rotated. If
working correctly the meter should show a voltage consistent with the throttle
position from approximately 1 volt when closed and 5 volts when fully open.
What is looked for is smooth
voltage increase with throttle change.
If there are drop outs in the transition or that there is no transition seen
the TPS is faulty.
How to fix? If the track is dirty causing drop outs, try cleaning it with residue-free electrical cleaning spray. If the track is worn it is perhaps easiest to replace the complete device. In some instances it may be possible to adjust the location of the central mount of the TPS contact arm along the throttle shaft by a few millimeters and in the process cause a fresh concentric region of track to be used.
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