map sensor voltage?
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Joined: Sep 2004
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It can run, but not well. The ECM has a "failure mode effects management" algorithm.
If it decides the MAP output is worthless, it will try to use the TPS voltage and PIP derived RPM to infer an approximate engine load and vehicle altitude and thus an amount of fuel to inject. This is a "limp home mode", so don't expect too much.
Sigrtn is a dedicated "virtual ground" back to the PCM. The idea is to isolate the relatively weak sensor inputs from all the ground noise caused by spark plugs, fuel injectors, alternators, etc. Attaching this wire to the engine block would be a bad idea; similar in nature and effect to the 60HZ hum heard from the amplifier of low-budget bar bands.
If it decides the MAP output is worthless, it will try to use the TPS voltage and PIP derived RPM to infer an approximate engine load and vehicle altitude and thus an amount of fuel to inject. This is a "limp home mode", so don't expect too much.
Sigrtn is a dedicated "virtual ground" back to the PCM. The idea is to isolate the relatively weak sensor inputs from all the ground noise caused by spark plugs, fuel injectors, alternators, etc. Attaching this wire to the engine block would be a bad idea; similar in nature and effect to the 60HZ hum heard from the amplifier of low-budget bar bands.
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acc7484
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Aug 11, 2005 10:22 AM
