Ticking/Pinging When Accelerating

CacalackChuck · February 3, 2003

I was driving up a steady incline this afternoon (70 degrees and warm motor) and noticed that when accelerating, I heard a persistent ticking or pinging. This noise is not to be confused with the ever-discussed piston-slap issue. Is this a common problem? I switched from 93 octane to 87 about two weeks ago (two tanks) due to outrageous petrol prices. I also add a bottle of Techron before each oil change.

Is this an exhaust issue or a faulty sensor somewhere? Any insight would be much appreciated

wlrottge · February 26, 2004

This may or may not be it, but...worth a try

Tech Info

99-2door · February 26, 2004

This may or may not be it, but...worth a try

Tech Info

That bulliten only applies to models with AIR.

varmint2506 · February 26, 2004

Sounds like spark knock to me. If you have always run 93 octane, switching to 87 may cause it to rattle under a load or acceleration. I'm sure someone will post an argument on this but, I believe that if you start with premium gas you have to stay with it. Most vehicles now are tuned for 87 octane, running 93 really doesn't give you much of an advantage unless you changed it in the computer.

If you have spark knock, the knock sensor will pick it up and adjust the timing to accommodate. The sensor adjustment is not immediate so your likely going to hear a little rattle until it compensates.

Just my .02 cents.

Cool Zr2 · February 26, 2004

I'm sure someone will post an argument on this but

Its not the fuel. Your PCM dosen't care what fuel you are running, but it does compensate for higher octane and you actually get less performance, because it is set to run on 87 octane, not multi grade.

Unplug your battery and let the computer reset, then it will have to learn your driving habbits again it it might fix your problem, if not, it could be the knock sensor going to crap.

Do you have a check engine light? If not you can still have a valuable code that hasn't required the SES light to come on, head to auto zone or the dealer to get the codes pulled.

99-2door · February 26, 2004

Sounds like spark knock to me. If you have always run 93 octane, switching to 87 may cause it to rattle under a load or acceleration. I'm sure someone will post an argument on this but, I believe that if you start with premium gas you have to stay with it. Most vehicles now are tuned for 87 octane, running 93 really doesn't give you much of an advantage unless you changed it in the computer.

If you have spark knock, the knock sensor will pick it up and adjust the timing to accommodate. The sensor adjustment is not immediate so your likely going to hear a little rattle until it compensates.

Just my .02 cents.

I dissagree,

When the knock sensor signals a knock it should immediately retard the timing until the knock is no longer present. In fact if a knock is sensed for a prolonged period a code will be set. You may want to test out your knock sensors.

99-2door · February 26, 2004

Your PCM dosen't care what fuel you are running, but it does compensate for higher octane and you actually get less performance, because it is set to run on 87 octane, not multi grade.

I wouldn't say that. You may not get a good benefit per cost from the higher octane, but you definately won't get a decrease in performance. In fact I would say the opposite, you may notice better acceleration with higher octane fuels. 93 may be a bit overkill, but still....

Octane is the measure of a Fuel's resistance to knock. The higher the octane, the less the knock. All OEM manufacturer engines must be able to run off of 87 octane, but they can recommend higher for better performance.

Higher mileage engines with carbon build-up have a higher effective compression ratio resulting in a higher tendency to knock.

I do agree that you may want to disconnect the battery cable to force the computer to relearn driving habits. It should self adjust in a short period of time, but that would be the sure way to do it. I'm afraid you may have a KS problem though.

varmint2506 · February 26, 2004

Its not the fuel. Your PCM dosen't care what fuel you are running, but it does compensate for higher octane and you actually get less performance, because it is set to run on 87 octane, not multi grade.

I believe the fuel brand and type has a lot to do with it. I can fill up at a Texaco in town with reformulated gas (ozone area) and I experience a small spark knock and lower fuel mileage. I can fill up at a Texaco out of town (non-reformulated gas) and do not experience any knock and my mileage picks back up. Both are 87 octane fuels. Brands and formulation in the same octane have a lot to do with performance, in my opinion.

Not trying to pick a bone with you Cool Zr2.

Cool Zr2 · February 26, 2004

Brands and formulation in the same octane have a lot to do with performance, in my opinion.

Not trying to pick a bone with you Cool Zr2.

That may be your opinion, but you are wrong.

And if you experienced knocking with 87 octane than you have something wrong.

I'm not gonna explain it to you cuz all your gonna go is say, nooollppp, I'm afraid not.

All premium is good for is costing more and gumming up egr valves on sfi vortecs.

My dad ownes a gas station and I have ran premium for the longest time untill one day the truck idled erratically, so I pulled off the egr valve, it was gummed up with goo, whick tells me that all of the fuel isn't getting burnt or something, then it happened a couple of weeks later. Not only that but it idled at 5% more engine load running on 92 than 87, so I switched back to 87. I also gained a couple of MPG.

The above is my experience, but like you, it is your experience, but a 22 year ASE tech at the dealer here knows all there is to know about anything related to GM and he will tell you that the PCM is set up for 87 and higher octane will not let it opperate properly as GM intended.

Hell, even your manual tells you to run 87.

ness5575 · February 26, 2004

i had an idle problem and thought that I would run a tank of 93 octane to see if that would clear up the problem. made truck run terribly worse. took it into the dealer (it was still under warranty) and when i told him i used 93 octane he cringed. told me that the truck is set up for 87, running 93 is a no-no.

Chad H · February 26, 2004

Thats the stupidest thing I have heard. The higher the octane is always gonna be better for your engine. 93 has alot more resistance to knock.

varmint2506 · February 26, 2004

I never said I was a fan of running 93 octane. I simply said different brands of the same octane will give you different results! I used the reformulated gas as an example.

QUOTE (varmint2506 @ Feb 26 2004, 09:50 AM)
Brands and formulation in the same octane have a lot to do with performance, in my opinion.

Not trying to pick a bone with you Cool Zr2.

That may be your opinion, but you are wrong

So from what you are saying, Cool Zr2, Amoco 87 octane will run exactly the same as all other brands of 87 octane fuel.

Cool Zr2 · February 26, 2004

So from what you are saying, Cool Zr2, Amoco 87 octane will run exactly the same as all other brands of 87 octane fuel.

I'm not saying that, my point was is that everyone has their own experiences. And no amoco 87 isn't the same as all 87, all gas companies have different additives that cause different results.

My point is, if your truck is made to run on 87 octane, 92 octane or 93 will not give you any performance without a pcm alteration like westers or a HPP3.

varmint2506 · February 26, 2004

My point is, if your truck is made to run on 87 octane, 92 octane or 93 will not give you any performance without a pcm alteration like westers or a HPP3.

Hmmm seems like I saw that somewhere... Oh yea my original reply.