that is correct and a hundred other reasons too.
stiff fluids in axles and tranny.
slow traffic do to slippery roads.
but he need to state how bad it is , as that says what might be wrong.
best is to have a fast warm up o2 , as his has. if working.
also not idling car at first start in AM.
run for 45second then drive slowly until you see stat open (on gauge)
the move above 45mph , gives best mpg.
45 is sweet spot
and the added benefit is less engine wear .
they learned this in germany ,long ago, using a very accurate Nuclear testing method.
it was repeat here, and found to be true.
the wear is measured by detecting radio active wear dust in the oil.
fancy , huh? cant do this with micrometer. sorry. (unless you are rip van winkle) lol
that is why remote starters stink.
faster the warm up the faster the activation of closed loop.
i can tell you my 91 never give below 25mpg, ,even last month ,driving rt 80 miles to work on ice. so that is a low num.
did that tune up include quality wires?
on mine, both the iat and iac were both drifted low (cold, or higher resistance the spec)
i replaced both when i found that. EG 45f out side, it reported 25f or lower.
this makes all starts very rich.
The next thing is make sure engine reaches full 180+ deg f. and not low for some reason.
lift wheels , spin them , make sure not dragging.
no one has the Vulcan mind meld box (obd1 tech1 tool anyone it seems).
so all readings have to be done fred flntstone way, DVM meter.
are you sure you are not dragging feet?
and fred sometime forgets to raise feet on long down hills. hahahaha
it is a huge list.
Bad-GAS-Mileage-Poor-MPG
i agree ,it is cold winter driving, and one more thing.
IAT/ECT drift.
and or , O2 is old and slow ,as they all do about 80k on.
but gas is so cheap, like only about same as bottle water.
i think cheaper than ever (60 to present) adjusted for inflation.
but , you want to save carbon , that you get 10 points for...
the two thermo sensors are a snap to test
wait till cold morn. then pop off conn. (has locks dont force them) and put meter on
R x 20k range. and read it or auto range ohms.
and see this for data.
actual factory and real devices.
temp-sensors
same year too.
