Your 1992 740-series Volvo, I'm rather certain, includes OBD-1 diagnostic function.
https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm
Throttle Position Sensor can fail at any time.
Do own a multimeter? How did you verify TPS function? By ear? Continuity, or unwanted conductivity, can happen no matter the symptoms heard.
Id suggest you available yourself to the many article in the FAQ.
https://www.brickboard.com/FAQ/700-900/
- Fuel Injection System Relay (reflow all broken solder welds)
- Air intake system leak downstream of the air filter, inclusive of all vacuum lines and duting.
- Faulty Wire Harness or Faulty Wire Harness Connector.
- Faulty coolant temperature sensor.
- The need for a tuneup. (Rotor, dist. cap, spark plugs or correct spark plug gap, air filter).
- Faulty EVAP
And more ....
Please diagnose your 740 for fault conditions.
Report results here to your thread.
Brickboard members shall reply with diagnostic suggestions and perhaps a solution.
Questions?
cheers,
Mac Cheesed Duff.
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