Pinging

[Ron Hickey]

My 97 GTS pings somewhere above 4000 rpm in 2nd, 3rd or 4th gear at WOT or close to WOT. This first surfaced about a year ago. My Viper tech adjusted something, and the problem went away for a while, but now it seems to have returned. But it is intermittent; this past weekend, on a great drive through some twisty & mountainous West Virginia roads, it popped up fairly consistently. But last weekend, in a similar environment, it happened only once or twice. I did two Viper Days events in July and August, and there was no pinging. While it may be gasoline, I always buy 93 octane from name brand dealers (Exxon, Amoco, Shell, Mobil, and Sunoco 94).

Car has 41K miles; I'm the original owner. No other problems except a replaced O2 sensor about a year and a half ago. Plugs and wires were replaced at 26K (stock Champions & stock Mopar wires). I plan to replace the plugs with Bosch Platinum Plus 4's and MSD wires. Also install some boot shields. And replace the fuel filter (which is still original). If these do the trick, great. But if not, does anyone have any suggestions?

 

[GTS Dean]

Ron,

Vipers are not equipped with knock sensors and spark retard. Your car has enough miles on it that it may be accumulating deposits on the valves, pistons and heads. These deposits reduce chamber volume and increase mechanical compression ratio, which in turn increases the octane requirement. The simplest (and most fun) way to loosen the deposits is with fuel additives and a full weekend at your favorite neighborhood road course. If that doesn't help, you might try one step colder plugs.

This is also about the time of year that the most refineries are making changes in their motor fuel formulations to improve cold weather vaporization. Depending on where you live and your local air chemistry, you may be getting out of, or into, your "clean air" fuel formulations. I would suggest giving it a couple of weeks until everyone's retail fuels are more consistent and see if the problem persists.

Tom Hayden, our very own "Fuel & Lube Geek of the Realm" can offer some more technical insight on formulations.

 

[gtsviper]

I had the same problem with my 96 GTS. The heads were removed and a ton of carbon had built up even though I used Chevron with Techron in the fuel. When the heads were inspected, the tech said he found "high spots" in the castings and ground them down. The car ran fine after that but both heads developed a coolant leak in the gaskets about a year after re-assembly. Good luck!

 

[Marc Lublin]

I had the exact same problem with my 94RT/10. It drove me crazy & my tech was clueless. It turned out to be carbon buildup on tops of my pistons. This causes hot spots which will detonate fuel when it is not supposed to. I got rid of the problem with GM's Top engine cleaner which I sprayed in my throttle bodies until the car choked out. Then I let the car sit overnight and in the morning started by letting it idle until you can't see smoke any more. Then drive the car hard. Unfortunatley the problem is probably caused by blow by past the rings which increases pressure in the motor. The extra air finds it's way up in the valve covers and blows out the PCV and breather. The car then ***** in these fumes mixed with oil. That oil is what ends up leaving carbon deposits on your pistons. I bet you have oil on your air filter and if you took off your tubes to the throttle bodies you would see a little oil there. Do not go WOT until you solve the problem. This detonation is very bad for the motor. My rod bearings were shot from the pounding of the pinging and I backed off any time I heard it. If you problem is caused by blow by it will end up coming back. Although the cleaner I put in helped, when I ended up taking the motor apart for other reasons, I found a huge amount of carbon buildup still on my piston heads. Good luck and please feel free to email me if you have any questions. I know how frustrating it can be.

 

[JimDavis MT 97GTS 650R]

Hi Ron, I too have had the problem you described. The use of a colder plug (I use NGK 7252's pretty much cured the problem. You still need to blow the carbon out with some hard runs occasionally.Oxygenated fuels aggravate the problem. <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ron Hickey:
My 97 GTS pings somewhere above 4000 rpm in 2nd, 3rd or 4th gear at WOT or close to WOT. This first surfaced about a year ago. My Viper tech adjusted something, and the problem went away for a while, but now it seems to have returned. But it is intermittent; this past weekend, on a great drive through some twisty & mountainous West Virginia roads, it popped up fairly consistently. But last weekend, in a similar environment, it happened only once or twice. I did two Viper Days events in July and August, and there was no pinging. While it may be gasoline, I always buy 93 octane from name brand dealers (Exxon, Amoco, Shell, Mobil, and Sunoco 94).

Car has 41K miles; I'm the original owner. No other problems except a replaced O2 sensor about a year and a half ago. Plugs and wires were replaced at 26K (stock Champions & stock Mopar wires). I plan to replace the plugs with Bosch Platinum Plus 4's and MSD wires. Also install some boot shields. And replace the fuel filter (which is still original). If these do the trick, great. But if not, does anyone have any suggestions?



<HR></BLOCKQUOTE>

 

[Fred(DrivingSchool)Kinder]

Make sure that the gas station is not diluting the gas storage tanks with Moonshine! West Virginia Crude that is! The Booze is less expensive than gas. FYI, I was born and lived there through college and then moved West! Most of my friends do not understand why I have one leg longer than the other, but Ron knows why.

 

[Ron Hickey]

Thank all of you for your input on this subject. I'll see if I can't get rid of these deposits with some additives before I try colder plugs or a mechanical cleaning.

 

[Tom F&L GoR]

Hi there.
Oil companies change the gasoline formulations about every two months to accommodate the ambient temperatures for each region of the country. However, this affects only driveability a little bit, since what they are changing is how readily the gasoline evaporates. Less volatile in the summer hot months, more volatile in the colder winter months. Octane does not change. Nor does octane change with "reformulated" gasoline or "oxygenated" or the 6 months/year "emissions" gasolines. Can't blame it on the gasoline composition change.

Combustion chamber deposits are just about the only cause for an engine knocking later in life when it didn't early in life. (excluding real mechnical problems.) As said above, either the deposits increase the compression ratio, are like "glow plugs" that ignite the mixture too soon, or can form ridges in the combustion chamber that don't allow good air-fuel mixing. The GM top engine cleaner will work, although there are other products that should work without the overnight soak requirement. STP Platinum or silver bottle is a good example. Of course, a mechanical cleaning will fix it, too.

These deposits are not all oil-related. Studies of the deposits show that they are just as likely, or moreso, from the fuel and the additives in the fuel.

If it works and you feel the need for another application, try *not* to use the fuel additive twice in an oil change. Some of the fuel additive gets into the oil and is too heavy a molecule to boil off during normal operation. Having a little reach the oil is OK, having twice that amount makes it depend on what the oil is and how new it is.