I have a 99 Ford Ranger (4cyl 2wd) with a manual transmission.  For years I was able to get by with running regular unleaded in it with no issues.  Over the last year or two I haven't been able to do it without problems.  If I run regular gasoline in it my engine makes a noise that sounds like ping-pong balls bouncing on a sheet of aluminum when I'm doing around 55-60 in fifth gear.  My little four banger doesn't have a lot of juice to it, and that speed is just a little high for fourth gear and a little low for fifth gear.  The problem is MUCH more noticeable if there is any kind of an incline (if I'm going up a really steep hill/mountain pass I basically have to slow down into third or fourth gear to keep the truck from making the noise).

I presume that is what is known as "pinging".  If I run higher octane gas it is far less noticeable (but still there).  I'm coming up on 100K miles on the truck.  I recently changed the spark plugs and set them to the proper gap but that didn't really help the problem.  So, any ideas what I can do fix the problem?  I'd like to be able to run regular unleaded again...

I'm guessing it may have something to do with the oxygen sensor, but I don't really know what the hell I'm talking about and it's just a wild guess on my part (I don't know all that much about cars).  Anything else I should be looking at?

Could be timing or timeing belt,  could be the gas, could be the valvetrain, ya may have busted a valve spring.

I would put some Octane boost in there and give it a tune up (plugs , wires, dist. cap and rotor, oil, filter, pvc filter, air filter, carb cleaner, etc)

I see ya changed the plugs already. being 99 im not sure if its O2, usually youll get a check engine light or a code if that was the case.

Not make ya sound like a dummy, but ya got the plug wires on correctly?

Quoted: Not make ya sound like a dummy, but ya got the plug wires on correctly?

Yup.  The truck was making the noise before I changed the plugs/wires.  I was hoping that would fix things but it didn't really seem to help at all.

Quoted: www.berrysweb.com/clean_your_maf.htm

Goddamn I love Arfcom.  Thanks for the link, I'll give that a try.

i'd say the timing needs to be checked.

carbon deposits on the intake valves.
partially blocked/dirty injectors.
incorrect valve timing.
weak timing belt.
a multitude of electronic failures.


Gary