Sometimes you just tap out!

This weeks tech tip comes in the for of poor electrical connection, internal to a component or the connector its self. Sometimes you can check everything and at that moment the system you are checking is working properly. So when you do your testing and you can’t find a fault, you may want to do some dynamic testing. This could be from changing the temperature of the components, wiggly testing, or even tapping on the component its self. I have a case study I did about a year ago on a 2009 Toyota Corolla with a cylinder 1 misfire. When I first started on it, the customer confirmed that it had been to multiple shops for the issue, and that the misfire was intermittent. The check engine light was on for cylinder 1 misfire, but the vehicle was not misfiring at the time of the diagnoses. During my initial diagnoses I had found cylinder 1 ignition coil connector pigtail harness had been crudely repaired. So I started with that, properly repairing the pigtail. After the repair I took the vehicle for a test drive and was getting a few misfire counts on cylinder 1, but it wouldn’t misfire while in the bay. After checking multiple things and changing the dynamics of the system nothing was causing a misfire unless I was driving it. So I decided to get my trusty screwdriver out and start tapping different components. This is when I was able to reproduce the misfire while in the bay, every time I would tap the fuel injector on cylinder 1 I could get the misfire counter to start registering misfires. After verifying pin tension at the connector, and integrity of the connector I was confident in condemning the faulty injector. For the people that are newer to the industry, when I say I tapped the component, I wasn’t referring to hitting it with a 10lbs sledge hammer. When you do tap tests you want to use something light but solid and just lightly tap components. When you are doing this you are almost simulation the vehicle is vibrating like it is driving down the road.