Hello to all,

I purchased a 2007 FX4 which currently has 52,000 miles. Almost every trip i take the truck will drive fine when its under load. When i come to a stop and the truck idles, every so often it sounds like i have rocks in the engine. If i let the motor idle the noise will last until i give it gas. When i give it gas the motor will go back to a smooth idle. The rpm is uneffected and there are no warning lights or code indications. I recently changed the air and fuel filters. Love the truck but this makes me frusterated. Thanks for your help from Canada.

 

what kind of octane are you running? check your timing?

 

Running regular 87. Timing is good.

 

I have the same problem, whenever I am in the hills driving at a low idle it starts to make an awful noise it has done this for at least three years.

 

if it sounds like marbles in a can, that is pre ignition. mine will do this if i use 87 big time. so i use the most expensive gas. it's a lil more mony but it stops the noise (pre ignition) and you wont burn a hole in ur pistens.

 

Thanks raz187. I'll give this a try. Take care.