Warning bells

A friend has a 1987 Mazda 323 4x4 Turbo with 52,000 miles. It has recently developed a snag under hard acceleration when a warning bell sounds above 4000rpm, followed by an engine cut-out. When the throttle is eased, the engine restarts and the car drives normally. When it's driven gently under light throttle and accelerates more slowly up to the legal limit, the alarm doesn’t sound. Tony Jackson

One of the more likely causes of this is that the ECU is detecting an over-boost from the turbocharger, possibly due to a faulty MAP sensor or wastegate actuator.

From the data I have, the vehicle should have a six-pin data-link connector under the bonnet; this should be found near the strut top, but locations can vary. Using a test lamp connected between terminals 1 and 2, turn on the ignition and the test light should illuminate for three seconds before beginning to flash. Long flashes will be the first digit and short flashes the second digit. If there are no codes, the light will illuminate for three seconds and then go off. Hopefully a code will be shown which should help in the diagnosis of the problem.

Codes can be erased by disconnecting the battery earth lead, pressing the brake pedal for three seconds and then reconnecting the battery.