Blinking check engine light
So the light started blinking and stayed on under hard acceleration. It's a 2008 f350 with 6.8. Truck didn't seem to be lagging in performance. Tomorrow I'll go to autozone and see what code it threw...
Forum Discussion
I was getting hesitation and bucking with no light at all. The Torque app with a blue tooth reader allowed me to monitor the misfire count for each cylinder on my 07 Expy 5.4 and see which ones had the problem. This was extremely useful. In my case, several cylinders were misfiring under load, but not enough to reach the limit required to cause the light to blink or set.
Another useful device is a HEI (High Energy Ignition) spark tester. You have to disconnect the coil and boot, put it on the end of the boot and connect to a good ground. It has a very large air gap and will stress test the coil. A failing or weak coil will not create a spark. This really is the absolute best tool to check a coil. They are actually very easy to remove, one screw holds them in place and disconnect the wire and pull out. Then reconnect the wire and put the tester on the end. Remove the fuel pump relay or disconnect the collision sensor so you do not flood the engine while turning over to check for spark.
Since all my coils produced spark in the HEI tester, I knew it was plug change time. Since this was the first, I just paid Ford to deal with it. I did not want to deal with broken plugs.
Another useful device is a HEI (High Energy Ignition) spark tester. You have to disconnect the coil and boot, put it on the end of the boot and connect to a good ground. It has a very large air gap and will stress test the coil. A failing or weak coil will not create a spark. This really is the absolute best tool to check a coil. They are actually very easy to remove, one screw holds them in place and disconnect the wire and pull out. Then reconnect the wire and put the tester on the end. Remove the fuel pump relay or disconnect the collision sensor so you do not flood the engine while turning over to check for spark.
Since all my coils produced spark in the HEI tester, I knew it was plug change time. Since this was the first, I just paid Ford to deal with it. I did not want to deal with broken plugs.
