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Old 11-03-2008, 05:07 PM   #3 (permalink)
amateur mech. engineer
Join Date: May 2008
Location: New York City
Posts: 112

Sporty Accord - '88 Honda Accord LX-i
90 day: 23.25 mpg (US)

Dad's Camry - '01 Toyota Camry CE
90 day: 22.81 mpg (US)

Artie's Camry - '98 Toyota Camry
90 day: 37.3 mpg (US)
Thanks: 0
Thanked 15 Times in 3 Posts
More mechanical problems

Here are some additional problems that hurt fuel economy:

More engine problems:

- high idle speed

- high fast idle speed when cold

- incorrect idle mixture adjustment (carburetor or fuel injection)

- leaking fuel line or carburetor (dangerous too)

- clogged jets (calibrated holes) inside carburetor

- defective power valve in carburetor

- worn camshaft lobes

- high alternator voltage (should be about 14 volts when warm)

- high oil level (interferes with crankshaft movement)

- high oil pressure (relief valve stuck or has wrong spring)

- stuck cooling fan clutch (runs fan when not needed)

Problems that increase rolling resistance:

- sticking disk brake calipers

- tight drum brake adjustment

- warped brake rotor or drum

- sticking parking brake cable

- incorrect wheel alignment, front or rear (check tire wear)

- worn suspension joints (ball joints, steering joints)

- worn control arm bushings (changes wheel alignment)

- worn or incorrectly adjusted wheel bearings

- leaking grease seals for wheel bearings

- use of snow tires when not needed

- leaking tires, causing loss of pressure

- warped tires

- bent rims, causing car to shake

- poor wheel balance, causing shaking at high speeds

- worn shocks or springs (forces driver to brake more)

Automatic transmission problems:

- wrong fluid level

- incorrect throttle valve cable adjustment

- bad vacuum modulator or vacuum hose to modulator

- sticking valves in valve body, causing delayed shifts; changing transmission fluid may help

- failure of torque converter to lock up (if equipped with lock-up torque converter); it should engage at 30-55 MPH, reducing engine speed about 10%

- stuck stator clutch in torque converter

Manual transmission problems:

- wrong fluid level

- excessive oil viscosity

- bad bearings

- failure to engage one or more gears

Differential problems:

- wrong fluid level

- excessive oil viscosity

- bad bearings

- high ratio ring and pinion gear set installed for racing
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