Thermostat question?
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Thermostat question?
I bought a 1996 F250 with the 460 motor, OBD2 a couple of months ago. While checking over my motor trying to figure out my poor gas mileage he found that i don't have a thermostat installed and that it could be the cause of my poor gas mileage along with his computer showing my O2 sensors going bad.
Would a thermostat cause bad mileage? he says it does because the motor never shows proper temp. The guage was always very low but i figured it was a good thing. Also will new O2 sensors help?
I know i will not see more than 10 MPG but right now i'm getting around 6 mpg's while using the back tank and 7.44 mpg's while using the front tank.
Would a thermostat cause bad mileage? he says it does because the motor never shows proper temp. The guage was always very low but i figured it was a good thing. Also will new O2 sensors help?
I know i will not see more than 10 MPG but right now i'm getting around 6 mpg's while using the back tank and 7.44 mpg's while using the front tank.
Post Fiend
Joined: Apr 2004
Posts: 6,473
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From: Lafayette, IN
With no thermostat, your engine is probably not getting warm enough for the computer to go into "closed-loop" mode--which means it's using stored fuel tables that allow you to fire up the engine and get it down the road. It also means that the computer is ignoring many of the sensors that allow the computer to respond to environmental variables--air temperature and pressure, engine temperature, O2 sensor, etc. Running slightly rich is generally safer for an engine (and also necessary for a cold engine), so mileage suffers when the computer is not actively involved, but using the default tables instead.
Jason
Jason
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Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
The dash temp gauges on these trucks typically read low.. often just a little above the first line or the N in the NORMAL range, so that's probably not your problem. The motor should have a 190deg thermostat in it and not having one would cause an increase in fuel consumption, but if it was missing completely the dash gauge would fluctuate a lot so unless the tech actually removed the upper rad hose and looked his diagnosis of a missing thermostat is false if it was just based on the dash gauge reading.
There should be no difference in fuel milage between front and rear tanks however so this suggests you have the fuel transfer problem, fixing this involves replacing the fuel delivery modules in one or both tanks.
There should be no difference in fuel milage between front and rear tanks however so this suggests you have the fuel transfer problem, fixing this involves replacing the fuel delivery modules in one or both tanks.
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bigbluetruck
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Feb 1, 2002 07:28 PM
