This document details troubleshooting steps for a 1999 Toyota Prado (3.4L V6) experiencing backfires and rough idling issues while running on LPG. The information is based on the experiences of forum users.
Problem
- Hesitation and potential backfire through the airbox during acceleration on LPG.
- Rough and fluctuating idle on LPG, both in neutral and in gear.
- Prior to repair: Actual backfire event causing damage to the airbox.
Solution
The immediate backfiring issue was resolved by:
- Replacing the spark plugs.
Further investigation suggested:
- Check ignition leads for wear and tear (replace every 80,000 km).
- Consider replacing spark plugs more frequently (every 20,000 km) due to the increased wear associated with LPG systems.
- Clean the upper intake and replace upper intake and rocker cover gaskets.
Relevant Parts
- Spark Plugs: Original spark plugs were ACDelco Professional Platinum.
Additional Notes
- The vehicle owner reported that the issues only occurred on LPG; the engine ran fine on petrol.
- The owner also checked for vacuum leaks, cleaned the throttle body and IAC valve, and replaced all vacuum hoses.
- It was suggested to seek professional assistance from an LPG specialist if further troubleshooting is needed.
This technical summary was auto-generated based on recovered archives. Do not rely on its factual accuracy. Refer to the original thread. Source: View Original Conversation
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