2002 Highlander
Customer complaint: car was running rough and it was not drivable.
Diagnose: one coil pack was not working.
Solution: replace the bad coil, inspect the other ignition components.
Work done: After testing the ignition system, the coil on cylinder no. 4 was found defective. Although the car didn’t run long with only three cylinders, the spark plugs were fouled with carbon. Also the gap was not according to the specifications. Maintenance time was coming soon, so all the spark plugs were replaced. As you can see in the photos, one DTC was related to an “inefficient catalytic converter”, which might have been caused by the car running too rich. After completing the repair, all DTC codes were erased.
Ignition system
The initial diagnose revealed more than one DTC.
The initial diagnose revealed more than one DTC.
The initial diagnose revealed more than one DTC.
The initial diagnose revealed more than one DTC.
The initial diagnose revealed more than one DTC.
The old spark plugs were a little fouled. The gap was bigger than in the specs.
Close-up of the old spark plugs.
New sparks plugs were installed.
The replacement coil.
The valve cover was extremely dirty from so many negligent oil changes...
...I decided to clean it up.
Here is a view with the coils installed. You can notice the replacement coil on the right side.
High quality diagnostic