Poor Fuel Economy
***UPDATED BY TSB #405489 DATED FEB. 20, 1989Mazda recommends the use of UNLEADED REGULAR gasoline only, in all vehicles not equipped with a turbocharger, unless otherwise specified. Do not use, or recommend for use, any higher octane fuels. Starting, idle, and driveability problems may result. See factory Technical Service Bulletin #405489, titled "USE OF REGULAR UNLEADED GASOLINE".
Definition: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy is noticeably lower than it was on this car at one time, as previously shown by an actual road test.
POSSIBLE CAUSE ACTION
Unmeasured air entering intake system (vacuum leak or Repair air leak
air leak between air flow sensor and throttle valve)
Dirty air filter Clean or replace
Rich air/fuel ratio Check closed loop computer operation.
Incorrect fuel pressure Check Fuel Pressure Regulator
Speedometer inaccurate Check speedometer calibration
Fuel leak Inspect fuel lines, tank, and fittings
Restricted exhaust system Check exhaust system, repair or replace as necessary
or catalytic converter
Exhaust manifold leak, or Repair leak.
fresh air entering exhaust.
near oxygen sensor.