Pinging under load - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 03-07-2008, 11:42 AM   #1
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Default Pinging under load

I have a 1995 SSEi w/ 130,000 with no problems except pinging in open loop under heavy load usually around 3-4,000 Rpms. It only lasts for a few seconds and I sometimes notice a slight reduction in power like timing being retarted?(no codes)
Closed loop operation has no pinging and power is 100%. Should I start w/ cooler NGK'* or clean MAF? Just recently got the car; haven't had time to really check stuff out like plugs, ect. Any suggestions would be appreciated.
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Old 03-07-2008, 11:55 AM   #2
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What'* the octane in the gas your using?
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Old 03-07-2008, 12:00 PM   #3
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Default Octane

Try to use 90+ as much as possible (depending on cash flow hehee) but have resorted to Mobil 89 some of the time.
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Old 03-07-2008, 12:05 PM   #4
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Danthurs has it right, low octane fuel is definitely causing the detonation. Detonation can cause engine-killing damage to pistons, especially when driving "spiritedly."

Operating an engine against the manufacturer'* requirements is not saving you money - it is almost certainly costing you money. Consider the following arithmetic example. Let'* say 89 octane costs $3.10 per gallon and 93 octane costs $3.35. That is 8% more for premium fuel. Your car will not only run a whole lot better on the premium fuel, it will also go more miles per gallon. For premium fuel to pay for itself, your miles per gallon would only need to increase by 8 percent. If you get 23 mpg on 89 octane, you would only need to see that increase to 24.8 to recover the increased price for premium.

Using low octane fuel in an engine that is designed for higher octane will cause detonation. Most of the time, you will not be able to hear the detonation. When you can hear it, it is really severe. But, even light detonation will be detected up by the knock sensors in your engine and "reported" to the PCM. The PCM will respond instantly by retarding the ignition timing to protect the engine from damage. This will result in seriously reduced performance and DECREASED FUEL ECONOMY.

If you drive 15,000 miles per year, at 23 mpg average, you will spend $2,022 for 89 octane fuel. If there were NO mpg benefit for using premium fuel, you would spend $2185 per year for premium, or $163 more per year. This works out to about $3 per fill-up. The engine will last longer, run better, accelerate MUCH more quickly, and generally be a lot more fun to drive and own with the proper fuel. The resale value of the car will be higher if it is running better. And, if you do break a piston, the cost of replacing it will quickly wipe out all the "savings" you thought you were accruing by abusing your car with low octane fuel.

The best fuel economy I have enjoyed in recent years was in a 1991 Corolla 5-speed. If I drove under 65 mph, the little car would give me 40 mpg. Compare that to 30 mpg in a good running L67 Bonneville that weighs 1000 pounds more, provides much more comfort and safety and you see why so many of us love this 3800 engine.
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Old 03-07-2008, 12:07 PM   #5
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Using the higher octane gas is about $3 or $4 per tank more. Not that big of a deal. Also, stay away from cheep gas, such as Marathon. I use only BP high octane.
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Old 03-07-2008, 12:47 PM   #6
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I will do that w/ some Seafoam and see how it goes over the next week. Thanks!
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Old 03-07-2008, 02:06 PM   #7
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Keep in mind that you'll actually end up spending more money on lower octane than higher octane

You get much better gas mileage with 93 than 89
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Old 03-07-2008, 02:18 PM   #8
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Something to remember; I've run into the problem, here, where some stations sell very little premium, since everybody is going the cheaper route. So be aware that some premiums may have been in the storage tank for a while; I guess, mainly, at the deep discount gas stations. Didn't use to be such a problem when it was only $.10-$.20 difference.
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