I was coming from the point that, sensor says cold engine, when it really is hot. But you could also say, sensor says hot, when really cold, so yeah that should work too. Though it does not take but just a few minutes to get the engine warmed up and with the guage having it's own sensor and not being synchronized to the coolant sensor, one could never really tell at what precise moment things are officially warmed up for the ecm.

If the ecm is receiving the temp as cold, even if the engine is really warmed, the trans will not shift into 4th gear. It is programed to keep the rpms up until warmed up. A bad coolant sensor that does not sense the normal operating temp. will cause the trans to not shift, and the engine to run rich.

Try this some morning, start up cold, and quickly get some speed, the trans will not shift to 4th until the temp guage is in the normal position. While on the early models, my 94 included the guage has it's own sensor. But if everything is working correctly that is how it supposed to work. With a good
t-stat one does not have much time for this even on a frigid morning.

Yes, the sensor is in a tight space, for me the most difficult part is getting the connector off, they didn't give much of a lead with the wire. Once off, an open end wrench working from the exhaust side of the head seemed to work best.

Hope this clears things for you.

DanR 94 964 279,000 miles (45,000 on the new engine)
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DanR