After owning my 1999 Chevy 1500 with a 4.8L V8 for a while now, I have noticed a steep drop in fuel economy after around 60,000 miles. I was getting around 16 MPG and then all of a sudden it dropped to 13-14.

I talked to another owner of this truck and he said that this economy decrease was a common issue with the 4.8 L engine. He said that Chevy was trying to address the issue but had not results.

Does anyone have any solutions to this fuel economy problem with high-mile 4.8L?

 

I always heard it has something to do with the pcv valves on the 4.8, try changing them out then let me know how it went. I have a 01 with a 4.8 also....