2012 Toyota Aurion 2GR-FE 3.5L V6 case study

We recently had a traveller with a 2012 Toyota Aurion reporting the vehicle is cranking over but not starting.

RAA attended the vehicle and was able to get it started and the vehicle was driven to our workshop. RAA noticed a portion of wiring harness had been eaten by mice and this could be the issue.

The technician then starting the process in diagnosing the fault. Whilst trying to start the vehicle he found it required a lot of throttle input to get the engine to start and run, he noticed the engine had a misfire on one or more cylinders.

First step was to check the engine oil level and coolant level, which were both full and clean and the customer had mentioned the vehicle was only recently serviced. All the control modules were scanned, and the following diagnostic trouble codes were stored.

• P0300 random multiple misfire detected
• P0301 cylinder 1 misfire

Next step was to carry out a battery, starter motor and alternator test. To just give a simple health check on the charging & starting systems, which in this case passed all test.

Next thing was to carry out relative compression test. Spark and fuel were disabled from the engine and the engine cranked over whilst monitoring the battery voltage with a laptop-based oscilloscope, we found that there were multiple cylinders were showing less than 80% efficient and one even showing 0%.

A compression test with a gauge was carried out on the front 3 cylinders which all had 150 psi which is within specification.

Next thing was to remove the intake manifold so the rear 3 cylinders could be checked. He noticed inside the inlet runner of cylinder 1 on the engine a shiny brass nozzle was spotted holding the inlet valve was open.

A mini slide hammer was used to remove the brass nozzle and a full compression test and leak down which both passed. The inlet manifold was re-fitted, and the engine started. The engine was now running smooth and passed a road test including re-scanning of the diagnostic trouble codes.

Under further inspection the technician had found that the brass object found in the engine was in fact a brass nozzle off specific tool. Our service manager had contacted the previous workshop where the vehicle was serviced. They had found that there were missing that particular brass nozzle, that workshop then paid for the full invoice.

The customer was pleased to find that the engine was not severely damaged and was extremely grateful for the fault diagnosing and repairing of the vehicle was done in a timely manner to get him back on the road.

Overall, we were happy to get the customer going again on his travels and for advising the other workshop that the tool they were using is possibly a defective tool.

-          Kristoffer Smith, Renmark Auto Service. 2022