I have a 1999 Ranger 4x4 3.0L V6. I am experiencing a engine rattle when I accelerate, especially while going up a hill. The problem goes away when I bump up the octane to say 89.

I feel like this is probably just a temporary band-aid. I am wondering what the real issue probably is, and if you can fix it. If so, what is the cost to do such work? Kind of just looking for the run down on it. I want my engine to last

 

how's the engine temp when it's pinging???

 

Have you done any engine mods?

 

My 98 (3.0) acted the same way. Spark knock like crazy and no power on the hills. I started running hi-test in it several years ago. The spark knock went away and I can pull the hills in 5th gear. It now has 222,500 miles and still runs very well. I justified my decision by doing the math. I get 19 MPG with 87 octane and 22 with 91 octane. I switched back earlier this winter and ran 4 tanks of regular in it. The gas mileage went back to 19 again. When I figure out the cost per mile, I am actually saving a little. The cost is 2 cents per mile more for regular gas.

 

Na, I have never done any mods to the engine. The temp is fine as well. Like Dan said, it really seems to labor unnecessarily on hills as well. I kinda figured that was mostly because its a 3.0l though...

 

I just tried on my way home this morning while the engine was still cold and it did not rattle. Not sure what that means

 

I have the same thing. Get a little bit at speed (60ish) when I lay into it. Tried some "cleaners" for oil, fuel, etc with no luck. Started putting 89 instead of 87. Has been fine for 8 months now as long as I run the 89.

Assuming $.08 a gallon more, and 15 gallons a week, in one year (14k miles) you have only spent $60 more. I figured to start throwing parts and headaches with trying to figure it further are not worth it at this point.