1998 ford expedition
2 Answers
Not much info to go on- when asking a question like this is helps to state what type of engine you have and how many miles are on it. "Making a noise like diseel," if I had to guess what would make a sound like that, along with a loss of power, is worn valve guides, valve seats, or in general a worn valve train (sounds like coke bottles rattling around). Who knows you might be hearing the timing chain rattling around on a whipped engine. Even if you are not showing a Check Engine Light you should scan for DTCs, and remember an out of tune engine will not make good power.
What you are hearing MIGHT be pinging. Try using premium gas to see if it goes away.