A loose or corroded ground terminal on the driver's side of the cylinder head can cause a rough idle, misfires, and there may be trouble codes. Restore the ground to the cylinder head.
1991 Mazda Protege Problem Reports
RepairPal Verified 1991 Mazda Protege Problem Reports
Misfires under load (acceleration) can be caused by leaky spark plug boots. When a spark plug boot leaks, it allows the spark to arc, or jump, to the cylinder head. New spark plug wires will be needed.
An electrically shorted air flow sensor can cause a crank-no start condition. Diagnosis may show that ignition spark is normal, and there are no trouble codes stored.
A loud ticking noise may be heard from the top of the engine, particularly when the engine is still cold. It may also be heard after the engine returns to idle after freeway driving. The noise is commonly caused by a lack of oil flow through the hydraulic valve lifters. Modified lifters are available to alleviate the problem. Following the maintenance schedule for oil changes will also help prevent a recurrence of the noise.
If the engine cranks but does not start, and diagnosis shows no fuel pressure, the fuel pump relay is frequently the problem. If the fuel pump relay is defective, the fuel pump will not energize and therefore, not generate fuel pressure so the engine can run.
The timing belt tensioner pulley may make a squealing noise from the timing cover area on cold startup. An updated tensioner with a thicker mounting bracket to eliminate vibration may be needed to solve the problem.