There was a lot of trouble in the '90s with the sending units causing fluctuating readings, especially at idle, so we did replace a lot of them. Also, there are different ones for different engines. The one I'm most familiar with is Chrysler's Mitsubishi 3.0L in the Caravans. On those it is acceptable to have only 6 psi at idle. That's way too low for most other engines. Their sending units are calibrated to keep the gauge reading in the "good" range at idle but that would result in a very high reading if it it was installed on other engines. If your high reading just started with the new sending unit, it sounds like you have one meant for a different engine or it was boxed wrong. Sometimes people check multiple parts at the parts store to match up a new part to their old one, then they put them back in the wrong boxes.
Monday, June 11th, 2012 AT 9:16 PM