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I think you may have a AMM failure here.
The air mass meter depends on the measurement of current flowing through heated wires to measure air flow. It is also known as the hot-wire sensor because of its heated wire design, hence the "H" in LH. In the unlikely event that a wire should break, the warm engine runs, though without fuel compensation, in a "Limp-Home" mode. For "Limp-Home" operation, injector pulse time is fixed. For any rpm above idle, the ECU is programmed to deliver fixed pulses, typically 7.5 milliseconds.
The air mass meter works by measuring the air mass, or weight, so it requires no correction for changes in density due to temperature or altitude. The hot wire system depends on the measurement of the cooling effect of the intake air moving across the heated wires. With a small movement of air past the heated wires, the cooling effect is small. With more air moving past the heated wires, the cooling effect is greater. LH control circuits use this effect to measure how much air passes the LH hot wire.
The LH hot wire is found within the air passage tube of the air mass meter and is made of a platinum filament. The hot wire is heated to a specific temperature differential above the incoming air when the ignition is turned on (the differential is measured in degrees Celsius).
* LH 2.2, aluminum: 212F (100C)
* LH 2.2 and LH 2.4, plastic: 248F (120C)
* LH 2.4.1 and 2.4.2, plastic: 311F (155C)
As soon as the air flows over the wire, the wire is cooled. The control circuits then apply more voltage to keep the wire at the original temperature differential (100 degrees C). For example, if the air is at freezing, 32F (0C), the wire will be heated to 212F (100C). On a hot day, if the air is at 86F (30C), the control circuits heats the wire to the same 212F (100C) difference to 266F (130C). This creates a voltage signal which the ECU monitors - the greater the air flow and wire cooling, the greater the signal. These signals are transmitted from the air mass meter
Grab an LH 2.2 AMM (84-89), from a wreck in a junyard. Check the part # if you grab on off a Saab or 240 or something, or borrw onE from anothr working 740.
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