I have a 2001 Ford Expedition with the 5.4-liter V-8 and
103,000 miles. At 98,000 miles, it developed a rough
idle and began stalling at stop signs.
local mechanic noticed low fuel pressure and replaced
the fuel filter and fuel pump. It ran good but then the
"check engine" light came on and the rough
idle and stalling returned. The mechanic could not find
anything wrong, but a scan found codes P0171 and P0174.
Another mechanic came up with the same codes and checked
for vacuum leaks but could not find any. I have
continued to drive the vehicle and the "check
engine" light is still on. Any suggestions?
My Alldata automotive database confirmed that the P0171
and P0174 codes indicate a lean fuel/air condition from
both cylinder banks. Since technicians have checked for
but not found the problem, I’d suggest a
"smoke" test to help identify any vacuum
leaks. This simple test involves introducing a nontoxic
smoke into the crankcase under low pressure and then
watching for any smoke escaping from the engine,
induction system or vacuum lines.
a ruptured diaphragm in the fuel pressure regulator,
located on the fuel rail downstream of the fuel
injectors, could cause low fuel pressure as well as fuel
leakage directly into the intake manifold. If there’s
liquid fuel in the vacuum line at the regulator, the
diaphragm is ruptured. Rough idle and stalling at stops
are often symptoms of a failed fuel pressure regulator.
I own a 2008 2.4-liter, four-cylinder Toyota Camry with
98,000 miles that I service every 5,000 miles. For the
past 15,000 miles, I have had to add 2 to 2 1/2 quarts
of engine oil between changes. The service writer at the
Toyota dealership tells me that 1 to 1 1/2 quarts every
5,000 miles is normal for these aluminum engines. I have
not noticed a decrease in engine power or any smoke from
the tailpipe. I bought this car new expecting to get
200,000 miles out of it. I think this is a lot of oil
for a car to burn.
One quart per 2,000 miles is completely within Toyota’s
"normal" oil consumption guidelines of one
quart per 1,200 miles. Your concern is due to the change
in oil consumption. Has oil use continued to increase?
Or is it stable at this rate? Unless or until the
consumption rate increases to excess, I would not be
oil use is being caused by a clogged PCV system or
"sticky" piston rings, there’s no easy
"fix." You could try de-carbonizing the
rings/grooves to free any sticking rings that could
increase the amount of oil reaching the combustion
chambers. Remove the spark plugs after shutting down the
hot engine and pour an ounce or so of SeaFoam directly
into each cylinder. After an hour or overnight,
temporarily disable the ignition and fuel injection and
crank the engine to expel any liquid in the cylinders.
Reinstall the plugs, re-enable the ignition and
injection, then start and drive the vehicle for at least
I use "high-mileage" oil and change it every
3,000 miles on my two high-mileage cars. What kind of
oil I should use when topping up the oil between changes
during this very cold weather? Would 0W-20 full
synthetic be the best bet? What is your opinion on using
0W-20 full synthetic for the regular oil changes during
the cold months?
When adding oil between oil changes, use the same
brand/viscosity already in the crankcase. Adding a
different oil isn’t harmful but the additive package
and viscosity are likely not the same. I don’t think
0W-20 would be a good choice in high-mileage vehicles
unless the carmaker suggests it in the service
recommendations. For most modern engines, a full
synthetic 5W-30 would be a good choice in cold