I have a '97 F-150 4.6. When I am on a freeway and I punch it, it takes off. It rattles but only does it sometimes. Any ideas what could it be? 140,000 miles. Thanks
When fuel injectors get dirty, they get carbon buildup and they often cause a rattle, and the valves can do the same thing. When you pressure clean the fuel injection system, that also pressure cleans the valves.
So, you would be getting two for one. It's cleaning the carbon of the fuel injectors and of the valves. A lot of times, that would fix it, because that is often what it is. It's carboned up engine doing it or it can also be the quality of gasoline.
Let's say you get the rattling to quiet down a bit. Go to Shell V-power and put in a high-test Shell V-power gas and see if it goes away. It means that you are using too cheap gas and it's not igniting correctly. It often happens when the engines get old. Sometimes they need higher grade gasoline as the engine wears inside.
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