View source for General maintenance

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[[Image:Maintenance.jpg|right|thumb|400px|Frame|]]
'''Introduction'''<br>
OK, so technically this isn't a mod.

But it must be said that the starting point for an efficient vehicle is one that's maintained in good condition. There's little point in building on a weak foundation.

Particularly if you're driving an older vehicle, there are a number of maintenance items that should be checked to ensure you're starting from the best possible position.

== Instructions for mod ==
Check for any of the following

- missing or defective thermostat, causing low operating temperature

- clogged intake manifold exhaust crossover passage (for heating intake manifold)

- engine misfire caused by bad spark plug, ignition wire, coil, dist. cap or rotor

- late ignition timing

- bad vacuum advance unit (common in old cars)

- stuck centrifugal advance mechanism in distributor (needs oil occasionally)

- bad tension adjustment of centrifugal advance springs

- defective oxygen sensor (causes rich mixture)

- defective coolant temp. sensor for engine computer (causes rich mixture)

- worn timing belt (may cause rich fuel mixture in fuel injected cars with a MAP sensor)

- incorrect timing belt installation (timing marks should line up)

- sticking or poorly adjusted carburetor choke (causes rich mixture)

- dirty air filter on an engine with a carburetor (causes rich mixture at high power)

- clogged or defective PCV valve

- incorrect valve clearance (especially if too tight)

- high performance camshaft installed (not efficient at low power)

- worn valve guides (makes fuel mixture too lean at low power)

- vacuum leak from bad vacuum hoses or intake system gaskets (causes lean mixture)

- dirty fuel injectors

- bad fuel pressure regulator

- bad MAP sensor for fuel injection

- leaking intake duct between air flow sensor and throttle body

- too much alcohol in gasoline with old car (requires carb. modification for correct mixture)

- rusted or missing exhaust heat stove or pipe for heated air intake

- loss of compression pressure due to worn rings or leaking valves

- sticking EGR valve (causes rough idling and rich mixture on some engines)

- exhaust backpressure caused by clogged catalytic converter, muffler or crushed pipe

- stuck exhaust manifold valve for some V type engines. Intended for fast warm up.

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

== User experiences  ==
Please enter your user name and any relevant data in the table<br>
{| cellspacing="0" Border=1
|+ User data
! User Name !! Car Make, Model, Year !! Cost of Mod !! Time to Perform Mod !! MPG Before Mod !! MPG After Mod !! MPG improvement guess !! Instruction Link
|-
|Example Data Saand || Example Data Mazda, 626, 1991 || Example Data $5 USD || Example Data 1 Hour || Example Data 27.2 || Example Data 29.8 || || [[Instruction_ModType_reference|User mod detail or measurement detailed data]]
|}


== Problems / Consequences of mod ==
''Information required:'' What are the consequences of the mod, Eg: drivability issue, stalling, engine wear,

== References ==
=== Forum thread links ===
[http://ecomodder.com/forum/showthread.php/list-common-mechanical-problems-hurt-fuel-economy-5322.html List of common mechanical problems that hurt fuel economy]

=== External links ===