Question about 1993 Mercury Grand Marquis
Its probably a problem with the water temperature sensor. Also do not rev a cold engine. The engine has a "cold start sequence" which is similar to a choke. When the engine gives a cold signal, the fuel mix is made richer and the timing is changed until the engine warms.
Let the engine warm at the preset factory settings. Sometimes the O2 sensors will cancel the cold start sequence before the water is warm. Racing the engine will warm the O2 sensors too quickly.
Posted on May 16, 2014
Testimonial: "i rev the engine a couple minutes after starting. the idle drops a little even after warmed up. now the idle roles a few hundred rpm more often. the reference voltage on the water temp sensor reads 3.0 volts on drivers side. should read 5.0. will replacing it help?"
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Posted on Jan 02, 2017
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