I have a 2011 Expy Limited, 5.4L. I have started noticing an I create in the frequency as to when I hear what I can best describe as rocks in a can type of noise, mostly when I reach a cruising speed or sometimes during acceleration. If I let up on the gas the noise will stop for a short time but it comes back. I use 90 octane (premium gas) also at every oil change I use a container of Lucas oil injector cleaner. I have approximately 146k miles. I use full synthetic oil as well. Could it be where we are getting our gas from or something else going on? Thanks for any advise or help.

 

Rocks in a can sounds like catalytic converter come apart. How does it run? If it won't open up I bet that's it.. I did have an issue with my own truck a while back where after a long pull I had a noise like that which accompanied severe engine miss. I started losing speed and downshifting until it completely went away. No noise and runs fine.. It was the first time id ever run the Lucas fuel system cleaner. I haven't used it since and haven't had an issue since. It's possible it passed a huge chunk of carbon but I don't know. Weird

 

I haven't had a loss of power acceleration is fine. I notice it more when I am accelerating and when I reach a cruising speed it happens at all speeds to 40 miles an hour to 75 miles an hour.

 

I'm sorry but I'm not going to be much help. I did have a little spark knock that'd happen a few years ago in mine too but haven't had that happen since I switched to premium (ethanol free) fuel which you've already done. Hopefully you'll set a code to help you out

 

Did some more research, could be a vacuum leak for the 4WD front hubs or the heat shield over the exhaust system is loose. I'm going to check those two things first, if I cant figure it out I'll take it to the dealership to get a diagnosis.

 

Let us know what you discover

 

Our appointment is to.orrow, here is an observation I had- When the switch is turned to 4A or 4h the noise stops and does not return. Once the switch is turned to 2H the noise starts back up. It has something to do with the front hubs. I'll keep you posted once the dealership gives a diagnosis.

 

Dealer diagnosed the problem as being both IWEs, and since this had gone on for so long both wheel hubs had worn out also. $1,889 later no more noise.

 

Drive our Expy on Sunday, the rattling noise came back. So for the IWEs, front hubs and a check valve have all been replaced.