Now that I've went back to using 87 octane gas(BECAUSE OF GAS PRICES), my engine is pinging again. It rarely pings on 89 octane though. My question is, will this pinging cause any damage to my engine? It only does it when I'm going 40-50 mph in 4th and 5th gear when the engine is at low rpm's. It's not too bad, but when I give it a little more gas at these speeds, that's when the pinging get's worse. Should I go back to 89 octane? Or will switching back and forth from 87 to 89 be harmful to my engine?

 

Wolverine;
Switching back and forth between octane ratings will not do any harm to your engine. Since your engine is designed to run on 87 octane fuel it seems strange that you would have a pinging problem. Have you seen your dealer for an analysis? If there is nothing wrong with your engine then it seems that the 87 octane fuel that you are purchasing may not be all that it is supposed to be. Have you tried different brands?

The pinging that you hear is bad for your engine. When you drive at low rpm's with wide throttle openings, you create high pressures in the cylinders because the engine has lots of time to take a very full fuel/air mixture into the cylinder. This is then compressed by the upward stroke of the piston and ignited by the spark. However, the increasing pressure in the cylinder during the compression stroke also creates heat before the spark ignites the fuel air mixture ( diesel principle ). If the temperature of the fuel air mixture reaches its ignition point before the spark occurs to ignite it, a spontaneous explosion will occur in the cylinder. This explosion is far more violent than the uniform burning of the fuel/air mixture that occurs when ignited by the spark plug and this explosion creates the telltale "pinging" noise that is heard. There are other contributing factors such as a lean fuel/air mixture, carbon build-up or hot spots in the cylinder, etc. Regardless of how it occurs, it is not good for your engine and a few extra bucks on a fill-up of higher octane fuel is cheap insurance against the damage that it can cause. Good Luck with your cure, GlennMc.

 

Had a 99 SC 4.2 that pinged after about 4k so I started using 89 octane until it could be taken back to the dealer. We were on a trip across Kansas where the wind always blows with a load of about 700 lbs. While I checked out of the motel my wife filled the truck with 87 octane and we had a head wind. Constant ping so I finally set the cruise and let it ping until I could run enough gas out to fill with 93 and mix it. After 50 miles the ping stopped and never happened again for the 2.5 years I had the truck. The dealer said the computer reprogramed itself to eliminate the ping.

I am not saying this is the way to stop the ping just relating what happened to me 3 years ago, because I would have never intentionally ran the truck like that trying to get rid of the ping.

 

I guess I'll have to stop being so "cheap" and put 89 octane in my truck every time I fill up. At least my engine will thank me... Thanks for the info.

 

Stay with the the 87 but try "better" gas stations. Or at least different stations. HHG

 

Well, I have been going to Phillips 66, the most expensive gas station in town. And I've also tried BP gas. Guess what? It pings on both brands of 87 octane. I talkled to Mike Troyer in the Computer chips forum about which gas is best, and he said stay away from BP because they have dirty gas. Texaco and Chevron or Sunoco has the best gas. In my town the only one of those 3 that we have are Texaco. But it's at a Dairy Mart, a small local convenient store. And it's actually alot cheaper than the rest of the gas stations around here. I try to avoid cheap gas, but it says on the sign that it's Texaco gasoline. Hey, if it's a good gas, I'll try it. What do I have to lose?

 

Originally posted by Glenn Mc
The pinging that...
...Good Luck with your cure, GlennMc.

Dang! Just what my engineering prof would say..

 

Mike Troyer is right. No 2 gas brands are the same. Try every gas stations' 87. In Canada, the best gas I have ever used is the Petro Canada winter gas. They add a number of chemicals to this formula (across all octane levels) and DAMN! no pinging, idles like a dream and crisp, clean acceleration.

If you are going to have to use higher octane, might as well get a chip and use 91 all the time.

 

I finally found a very good gas. It's Chevron (with Techron). My pinging was so bad on other 87 octane gases that I had to put some 89 Chevron in my tank to prevent damage. Guess what? The pinging stopped within 20 miles. I may be imagining things, but my temperature gauge went down a little. And my engine runs silky smooth now like it should. I'm stickin' with Chevron 89.