Pinging

[wtd]

For the last couple of months, the 5.7L in my 98 Chevy truck has been pinging under load and under initial acceleration. My owner's manual says this is normal and not to worry unless its heavy knocking. All of my ignition components are fairly new and I use FP in about every tank of gas. Truck has 61,000 miles on it.

What else can cause pinging?

Does anyone else experience this problem on their vehicle?

I hate hearing this noise and would like to find a way to stop it. Thanks for any ideas.

Wayne

 

[sbc350gearhead]

Buildup of deposits in combustion chambers. Low octane, low quality fuel. Excessive operating temps. High intake air temperature. Ingition timing too far advanced. Try 89 octane fuel, and see if that helps..........or perhaps change gas stations.

 

[n8wvi]

I agree w/ the possible causes, but would offer alternate possible solutions. If it's due to combustion chamber deposits, an appropriate dose of Pennzoil (Gumout) Regane combustion chamber cleaner or Chevron Techron concentrate may very well relieve the symptoms and allow you to continue to use 87 octane.

Dave

 

[SteveD2]

I strongly suggest a can of Seafoam poured into the intake as directed. This stuff does a REALLY good job of cleaning out any carbon that might be in there...smells good too!

 

[Chris142]

How about a bad knock sensor?

 

[Kestas]

Reflashing the computer under warranty cured knocking on my '01 Sable. There was a TSB on it. See if there is a TSB on knocking for your vehicle.

 

[wtd]

Guys,
Thanks for all of the ideas. I really don't want to move up in octane if I don't have to. I have used GM top engine cleaner in the past and have regularly used some type of fuel system cleaner including Chevron Techron since then so I'm not sure its combustion deposits.

My SES light is not on so I don't know about the Knock Sensor. It could be getting less efficient.

What about my O2 sensors? I know these newer type heated ones are supposed to last at least 100,000 miles before needing replacement but I'm not sure if they do. The last time I scanned my truck the O2 sensor values looked pretty good though.

I am getting the "corona" effect on my coil and plug wires again and am wondering if this is the cause.

Thanks again for all of the replies.

Wayne

 

[manualman]

I looked into this years ago because my Saturn did something similar. Does it just do a light ping at the start of your medium to heavy throttle setting and then go away for the rest of the time you maintain that same throttle?

That really is normal. GM ignition timing is all electronic. Timing is set using a crankshaft position sensor that detects a magnet on the crank every time it rotates past. Spark timing is based on this sensor instead of a traditional distributor. However, GM has also programmed the computer to frequently advance the timing until the knock sensor detects a ping, then back off slightly. This allows the engine to maintain optimal timing (and resultant mpg / emissions)without frequent tune ups.

Helps GM get around 30 mpg highway out of a big car like a Buick Regal with a 3800 cc V6 engine. Or over 40 mpg highway on my 1.9 liter Saturn. Pretty impressive, actually. One of GM's better areas of competitiveness.

 

[wtd]

Manualman,
that sounds pretty much like what I'm experienceing and my owner's manual states that light pinging under load is normal but the truck didn't do this when it was newer. Its just a pet peeve of mine and I don't like it.

Wayne

 

[Chris142]

[
I am getting the "corona" effect on my coil and plug wires again and am wondering if this is the cause.


[/QUOTE]

Quite possible. This could burn a hole in a piston. You need to get the wires replaced then see if it's still rattling.

 

[Darryl]

The 2 simple fixes are: 180* t-stat (stock is 195*) and 1 step colder sparkplugs.

Also use copper-core plugs and not platinum, the copper helps to dissipate heat faster than platinum and the colder plug will eliminate the pre-ignition.

It is not at all good for the motor to ping, regaurdless of what GM says

Darryl

 

[T-Keith]

quote:

---

Originally posted by manualman:


That really is normal. GM ignition timing is all electronic. Timing is set using a crankshaft position sensor that detects a magnet on the crank every time it rotates past. Spark timing is based on this sensor instead of a traditional distributor. However, GM has also programmed the computer to frequently advance the timing until the knock sensor detects a ping, then back off slightly. This allows the engine to maintain optimal timing (and resultant mpg / emissions)without frequent tune ups.

Helps GM get around 30 mpg highway out of a big car like a Buick Regal with a 3800 cc V6 engine. Or over 40 mpg highway on my 1.9 liter Saturn. Pretty impressive, actually. One of GM's better areas of competitiveness.

---

This is correct, but the 350 chevy still used a distributor in 98, not quite the same as the 3800. You should never hear knock though. The computer should pull timing before this becomes a problem.

You really need your truck scanned to make sure this is really knock.

-T

 

[wtd]

The wires on this truck are AC-Delco replacement wires and are fairly new. I've had an ongoing problem with "Corona" on my wires and coil after very few miles. This has been going on for the last 26,000 miles. If I replace all ignition components with new, I don't get any pinging, but in about 3-5,000 miles, the pinging and corona come back.

Where can I find a copper core plug that is one range colder that cross references with my factory platinum plugs?

My truck's SES light is not on and has never come on while driving. I have an AutoXray scanner and everything reads normal.

I will probably replace all of my ignition components again and use Magnacor plug wires instead of the factory Delcos. My personal opinion is that the factory wires and plug wires in general are the weak link in the ignition system on these trucks. Thanks for all of the input.

Wayne

 

[Darryl]

Any Autozone/Pepboys/Kragen should be able to cross reference a colder plug. Usually, the last number on a plug is the heat range, and the lower the number the cooler the plug.

Autolite makes a coper core plug that is pretty well thought of. But all manufactures make a coper core plug.

Platinum will work, but you might have to drop 2 heat ranges and this could cause self cleaning problems and lead to fouling.

But if I had a guess, I would think you would be ok with either plug, But I would go with the coper core's 1 range cooler

Darryl

 

[leinad35]

I wouldn't switch from OE platinum plugs. You are bound to set off the "Check Engine" light as these late model vehicles are quite particular in what they use.

 

[Darryl]

On a '98 5.7 you'll be fine with either plug and you will not throw a code for non-platinum plugs.


Darryl