I have a 1997 F250 with the 460 with 130K on the clock. I have owned it for a little over a year and in this time I have noticed a problem. When accelerating to speed I hear no knocking, however after reaching a cruising speed and then trying to accelerate, without enough gas to gear down, the engine is knocking, lugging. I notice it most on hills where the engine would be under load. It doesn't matter which gear the tranny is in. As soon as you give it enough gas it downshifts and the knocking goes away. I am unaware of the maintenance of the plugs and wires. Where should I start looking? Does this sound like a tune up problem or something more?

Any advise would be greatly appreciated.

 

my 97 w/7.5 also pings some times same situations i only have 51k on the motor i live in CA were the gas is crappy if i put octain boost it goes away, i only run boost when i tow.Also if i put in 89 it doesnt do it as much.

 

Thank for the response, but I wonder if that is the problem. I could easily try the octane booster, but my understanding is that the engine should be running fine on 87 octane. So if it is not, what is the problem?

 

It could be an issue of advanced timing causing the ping. Have you had a chance to check the timing and do a tune up?

 

I have not had the timing or completed a tune up. I need to do the tune up, but wanted to be sure I was not going to start throwing parts at the truck without knowing what the problem was.

 

with 130K miles you may have carbon deposits in the chamber. You might try some Techron to see if that helps clean things out.

Also you might check your plugs to make sure they are the right heat range and clean. Old plugs can have hot spots and the wrong plugs can easily cause pinging.

My 94 F250 with E4OD 4x4 and 460 with 4.10 runs fine on regular with no trailer pretty much any time of year. If I get into a long hill in hot weather it might ping a little.

If I tow my 8,000# trailer, especially in hot weather and hills it will ping a lot unless I use at least 89 and in severe heat maybe even 92 octane.

When towing and if I want to be cheap, I often will fill one tank with 87 and the other with 92 and switch when I get into pinging.

Good Luck,

Jim Henderson

 

Interesting, care to elaborate on plug heat range and pinging? Are hotter plugs gonna be more susceptible to pinging? Why?

Good info Jim

 

A fast easy way to get rid of carbon deposits in an engine is to remove the hoses from the aircleaner box or the air cleaner itself depending one weither it's carberated or FI, then with the engine running hold it about 2000-2500 rpm and using a spray bottle like a windex bottle or something along those lines spray water into the intake this will blast all the carbon outof the combustion chamber, and off the pistons tops. I used to do this to engines that were still running that I was going to rebuild, and when you tear them down the pistons will look like they are brand new.

 

I have heard of doing this with carb cleaner, but not with water. Are we talking about the same process?

 

Assuming that with 130K miles that you are not the original owner, it is possible that the previous owner put in a set of plugs that is not the appropriate heat range per the manual. If you are just replacing with what you pulled out, you may have the wrong plug.

I don't have the technical specifics, and I am NO expert, but each plug maker makes a set of plugs that fit an engine and they can have different heat ranges. I forget the coding but usually it will be like RNC55 RNB55 and RND55 or something like that. The RNC55 is the standard and the B is colder the D is hotter. Usually the compatibility guides in the parts store tells how to decode a plug. Each letter and number mean somthing to do with heat range, thread diameter, length of thread, resistive etc. I almost never need to do this now due to my dull life style ;^) so I probably got the details wrong but the idea right.

Different heat ranges mean that the plug will run hotter or colder than the standard plug for that engine. Usually a person will choose a colder running plug because of heat issues like racing applications or pinging etc. The problem is that a colder running plug can foul up from deposits that don't get burned off. A hotter plug is one that runs hotter and is used to burn off depositis, usually oil from an engine with oil issues.

Colder plugs have a less deep channel between the porcelin and the shell. Hot plugs have a deeper channel. The depth of the channel affects how well the plug cools itself.

Hope I got things right, but in general the conecpt is there.

Good Luck,

Jim Henderson

 

don't know what you mean the same process, carb cleaner is flamable, and it evaporates before it gets to the cyl water doesn't and it does blast the carbon clean out of the cylinder and off the valves, if you want an example to see how well take your lawnmower head off, and check it then reinstall and mist some water down the carb, and remove the head again, and look at it you will see a huge difference.

 

Like how much water are we talking about? How do you know when you have sprayed enough?

 

I am talking about using a spray bottle and a stream from something like a windex bottle. As long as it doesn't die you aren't spraying to much although you will have to hold the throttle open while your doing it (like I said hold it around 2500rpm) you can spray as much as you like it's not going to hurt anything but about a cup run through should get most of the deposits out, and yes it will sputter, and smoke a little then when your done spraying it with the water drive it around the block or upto the store and back before shutting it off to clear it all out. BTW you will probably find that using a spray bottle like that you can't spray it fast enough to kill the engine as long as your keeping the rpms up a little.
Oh one other thing I didn't mention it works best if you bring it all the way upto operating temp before you start although it will work on a cold engine just not as well.