Just thought id pass on some info of a random misfire I was dealing with for years that has a rather silly fix. I know this has been most likely discussed before, but it is hard to search for. I was dealing with random misfires that would come and go for no reason. Almost like water in the fuel, a bad coil, injector etc. Would never throw a code but drove me insane as everything ran fine otherwise. It also had the exhaust manifold leak sound under load in overdrive so I was thinking that was the problem as well.

At the time it was trying to diagnose this, I was spending a lot of time on the Interstate traveling from Northern Virginia to Atlanta twice a month for almost 2 years. I began to notice it was always the worse on colder days when it was windy, or there was a tractor trailer ahead creating "wake turbulence" going under the hood. Began to realize it was probably an issue with air delivery and found the airbox the air filter sits in was warped from the clips that hold it in place pulling tight. Even with weather stripping on it, it was still warping bad enough over time to cause issues. I ran my finger under the airbox on top of the snorkel and lo and behold there was a gap there. My feeling is that this gap was allowing hot and cold turbulent air in at different intervals and throwing the MAF (mass airflow) all out of wack. Just not bad or long enough to make it throw a code.

My fix has been to pull the airbox out, take the clips off and place it in the oven at a low temp 180-250 degree range. Be careful as too hot will melt it obviously, but a nice slow heat soak will cause it to go back its original shape. Pop it back in and misfire is gone. Not spending over $100.00 for a new one.

Just thought id pass it along. I was convinced I had a bad injector/coil etc. Half the time its always something stupid.

Here is some pics that are hard to see because the iphone 6 camera sucks, but looking closely you can see the bend at the bottom of airbox.