pinging noise

ness5575 · June 29, 2004

My truck recently started making a pinging noise. i noticed it first when going up a fairly large hill near my home at about 40-50 mph. i pulled the atv's up north this past weekend and it was pinging most of the way - especially up any sort of incline. it reminds me of the noise my old 5-speed '87 corolla (college car) would make if i had it in too high of a gear.

any thoughts on why this may be happening??

silversub · June 29, 2004

What octane gas are you using? Modern, computer controlled, engines automatically reduce ignition timing to eliminate pinging and detonation. Sounds like in this case the timing could not be reduced enough. Do you ever notice this during normal driving (without a trailer)? If not, I'd just fill up with the next higher octane gas the next time you plan to pull a load like this or heavier. If you do notice pinging during normal driving you may have a mechanical/computer problem.

ness5575 · June 29, 2004

i do notice the pinging occasionally w/o the trailer. usually only when going up a hill.

i usually use 87 octane. i did try 89 octane on the way back home with the trailer and it did seem to improve it (pinged less), but did not remove it.

i am hesitant to run higher octane though because my old service manager told me that i should never run anything besides 87 octane in the truck - said running higher octane would confuse the computer and trip an SES light.

silversub · June 29, 2004

OK. In my mind you do have an issue if you hear pinging without towing a load on 87. It is generally accepted that this type of light load, high engine vacuum, pinging does not hurt the engine but I never like to hear it. In the old days we simply reduced the amount of vacuum advance at the distributor to cure this. Not so easy today.

Is this new or have you been hearing it for a while? It may simply be carbon build up in your combustion chambers (on valves, piston top) which reduces chamber volume and increases the compression ratio. A good clean out may help but the carbon will come back so this is not a permanent cure. I agree, use the lowest octane you can but you also don’t want to hear pinging or detonation (worse).

robsawatsky · June 29, 2004

Either something has gone wrong with your engine controls, too much advance or too lean fuel mixture, or more likely, engine deposits (as previously mentioned).

And there is absolutely no way using higher octane will cause an SES light to come on. Some of the newer oxygenated fuels may do some weird things, mostly to performance and fuel economy, but the only typical indication that the computer would get from an octane change would be a lack of ping so it could use the full ignition advance it was designed for, which is based upon 87 octane.