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5.3 Pinging Under Load...

M

MrYum

Full Member
Joined
Jun 19, 2002
Messages
15
Location
Florida
Well, I've been pretty lucky so far. Have a Black Z71...born 06/01...purhased 07/01. Haven't really experienced any of the problems the early builds are known for...knock on cladding :B:

Do have an intermittent cricket sounding squeek under the driver's side dash off and on, but no big deal. Someday the dealer will figure that one out ;D

Anyway, to the point of this message. I've noticed over the past few weeks that I'm getting a bit of engine ping under load. First time I noticed it was on the freeway, cruising about 70 with A/C on...hot day...100+. Went to pass a car and noticed during WOT...engine ping.

This past weekend, while towing my boat (about 3500 -4000 lbs)...same thing, while under WOT...engine ping. This time I actually tried to re-create the ping... wondering if the computer was learning something new about hot days and running under heavy load. Was able to get the ping pretty much every time under WOT.

Usually, I feed it Chevron regular...but this past weekend...I actually gave it mid-grade. I ran a search before posting this message and saw where one person mentioned that Chevron fuel in California caused ping in his truck...sooo, maybe time to change brands?

Okay, so the question...is this normal for a 5.3 that's working hard on a hot day? Or, could this be related to the Chevron fuel? Or, is it time to take the big black beast to see the doc?

Oh, lastly...no performance mods...YET! Other than some cosmetic stuff...and Mobil 1...she's bone stock :B:

Thanks folks...this is an awesome site! And believe me, I see a LOT of websites >:D
 
? well i was going to ask you about the gas you use, but you already covered that. ?on another thread some guys posted that they only upgrade fuel when they are towing.
? as for the pinging being normal while you tow; ?i don't think so. ?i have towed a trailer from VA to FL and back this summer and had no problems. ?the trailer probably weighed about 2500 to 3500lbs when it was loaded. ?maybe this does not create the load you spoke of on the motor. ?it is possible it could be the gas.
? i only use Exxon or Mobil. ?on that FL trip however i got gas whereever was convient and cheap since i was not paying. ?i still had no problems. :B:
 
I was talking to a friend of mine about the Avalanche a few days ago and we were going over the specs for the engine. He noticed that it had a rather high compression ratio for an engine that runs on regular gas. He recommended that if I was ever going to be towing/hauling something heavy that I may want to at least put mid-grade gas or higher in the tank to avoid pinging under load.
I am not sure if this is valid or not, but given what you have just said, it might actually make sense. You want to hear from other people who have hauled heavy loads with the 5.3 and used regular gas.
 
Sounds like a fuel issue....if it has not done this before and now it starts too.....or you may need a tune up which I find highly unlikely.....
 
Hey guys...

Thanks for the responses :B:

Irontrain...yes, I had seen that thread...that's where someone else mentioned pinging problems on Chevron fuel here in California.

Also, I normally run regular...but decided to fill with mid-grade due to the heat and towing this time. And I've experienced the ping with both grades of fuel. Once without the boat and once with the boat. But, both times I noticed the pinging was under heavy acceleration on a hot day with A/C running.

Hmmm...based on responses so far...think I'll try a tank or 2 of Unocal regular and see if that helps. Here in the Bay Area, Unocal gas is formulated without MTBE's. Perhaps that will help....

And if not, sounds like it's time for a visit to the doctor :B:
 
MrYum said:
And if not, sounds like it's time for a visit to the doctor :B:
Click to expand...
Just don't be surprised if "the doc" says that nothing's wrong. A small amount of pinging under heavy load or acceleration is considered normal, according to Chevy. :rolleyes:

(I don't remember where I read this, I think it was the trouble shooting charts in the factory service manuals.)

-- SS
 
Fuel additives vary not only from state to state but also time of year. Example...the fuel in Colorado is different in summer than in winter. So I've read. EPA stuff
 
Ahh...SS...you were right on!

I just got off the phone with the service dept. And exactly as you anticipated, they say this is normal under heavy load.

He said that these new engines are set up running fairly lean and with timing advanced. He went on to say that it should not ping for more than a few seconds as the computer adjusts and retards timing to stop the ping. I'll have to experiment with this a bit and see if it actually stops after a few seconds.

And he confirmed 87 octane fuel all the time...whether towing or not. Said that anything more than that can cause problems.

He did say that the Chevron fuel 'could' be part of the issue, so I still think I'll try a couple tanks of Unocal and see if that helps too :B:

What a great resource...thanks to one and all!
 
The dealer told you not to use more than 87 octane fuel.

I have been running Premium(91) since I bought mine.
Anyone else know any wrong with running Premium??

I thought I saw a previous thread on here where fuel milage increased a little with premium. like 15 to 20 %.
 
kegger said:
The dealer told you not to use more than 87 octane fuel.

I have been running Premium(91) since I bought mine.
Anyone else know any wrong with running Premium??

I thought I saw a previous thread on here where fuel milage increased a little with premium. ?like 15 to 20 %. ?
Click to expand...
My understanding is that the octane level has nothing to do with mileage and does not directly affect the amount of power. Note, I am not an automotive nor chemical engineer. I'm not even a gear-head. Take what I say with a grain of salt.

Generally, the higher the compression ratio of an engine, the more likely it is to ping or knock. Severe engine pinging can cause damage. Octane helps prevent that pinging. Basically you need to use a certain amount of octane to prevent the majority of the pinging. If you use octane that is higher than that what's needed, it's just wasted money. Our trucks are designed to run well on 87 octane, using higher will not give any real benefit to a stock truck. (I have heard comments elsewhere where using too high an octane can cause problems. I don't know what the mechanism is there.)

Even though our engines are relatively high compression, the programming in the computer prevents most of the pinging by running lean and with the timing retarded.

Increasing the octane will not directly increase the power to the engine. Octane is the resistance to detonation (or pinging) not the amount of energy in the gas. However, if you use the HPP3 or Superchips (shudder) you can reprogram your engine so that it can make use of the higher octane. The reprogramming enriches (adds more gas to) the mix, and advances the spark timing. It is this re-programming that gives more power, not the octane itself. However, once that reprogramming is done, you must use high octane gas to prevent severe pinging and possible engine damage.

As for an increase in mileage, that's not a claim that I have seen made very often, and I don't see why it should happen.

-- SS
 
In order to derive a benefit from higher octane gas the engine needs to know what to do with it. I don't know enough about the electronics in the Avalanche to know if it does or does not benefit.

When I owned my Ford Probe way back when in another life the computer was able to make adjustments for higher octane and afforded better performance. Because of that I ran Sunoco Ultra 94 in it all the time, and gave it some Cam-2 101 every now and then. Man did that thing run like an animal on the 101 and the engine was clean clean clean. Bottom line, I got raging good gas mileage if I didn't lay into it.

Again - I don't know if the Avalanche and the computer there in has similar features. The Probe had this due to the forced induction...
 
It sound to me like you are dealing with bad fuel. I tow every weekend 5500lbs to 6000lbs and I have never had a time where my engine had a ping or knock. Maybe you should try different stations you haven't been to before. I don't know. It sure does sound like a fuel problem and not a AV problem.

MOD ON

Wiki
 
All good info...thanks again guys :B:

I do think I'm going to try some Unocal fuel. Prior to buying the Av, my old K5 Blazer always ran pretty lousy on Chevron gas...it greatly prefered Unocal. I always assumed that was because of it being an older vehicle without all the new computers...perhaps not.

The Av is due for a fill up now, so I'll be heading to a Unocal station and top it up. Will post again when I know more...I really do think this could be related to the lousy gas we have here in California :9:

And now that I think of it, my Valkyrie runs better on Unocal fuel too. I'd just always heard that Chevron had the best detergent additive pack...that's why I was running it in the Av. Only time will tell :B:
 
I too have had pinging under WOT. Once I was in Austin getting onto the highway with no trailer and got on at WOT and it pinged for a couple of seconds. The other time I did have a trailer and was towing. Same thing happened. I usually put 87 oct. from Texaco and Chevron. Not sure if it is the fuel or the engine. Keep s posted if you find something out.
 
it probably would not hurt to add some Mystery Oil (purchase from your local automotive store or Wal-mart). put in the Mystery Oil right as you are about to fill up with the 87 octane to clean any build up that might have taken place. hopefully this and the 87 octane should solve any problems. ;D
 
GM installed one of those crickets into my dash also :C: It would be more likely to appear if I drove down a rough road, and I then could replicate the problem by lightly hitting the dash by my right knee. Needless to say when I took it to the dealer I drove over as many road turtles as I could then took the service manager out to replicate the problem for him. :8: The problem turned out to be a broken clip. Hope this helps.
 
Hey there Stinky...

Hope ya don't mind me calling you that, but you picked it! ;D That's one heck of a handle!

Yup, I think we have the same crickets. My dealer has pulled the kick panel directly under the steering column and insulated it...seemed to help for a while, then the crickets were back. And also yes, thumping it with the palm will re-create it...when the crickets are in the mood to sing. The other thing I've noticed when they're singing is I can take my hand and grab the sheetmetal behind that kick panel and stop the crickets. Oh well, this is a very intermittent thing on my truck...and eventually they'll get it fixed. Next time it's in, I will ask em to look at those clips again though...thanks for the tip :B:

Z66, um...no offense intended, but I really don't think I want to put Marvel Mystery oil in my $40k truck. I know nothing about the stuff, but the name alone just don't sound right...again, no offense is intended here :)

I'm going to try a different brand of fuel and if that doesn't do the job, I'll let the dealer figure it out. Thanks much for the thoughts though.
 
I had a 99 GMC P/U w/ the 5.3 before I got my AV and the only time it ever had any detonation - ping problems was the one time I filled it with 93 oct. fuel. The 5.3L has a compression ratio of 9.5:1 and the 8.1L is 9.1:1
Either of these should run fine on 87 oct fuel. I do recommend that you consider pulling the battery for a few hours to let the computer "reset". I say this for good reason, as I let my brother use my AV for three months while his Tahoe was at the body shop and upon the AV's return to me under WOT from 4,250 to 5,300 RPM it sounded like the bottom end was about to go straight thru the oil pan. He drives much slower and easier than I do and the computer got "trained" to that style of driving. After leaving the battery disconnected for the night it was all better. :B:
 
? mr yum i know what you mean about the mystery oil name.. ?sounds a little "mysterious" right? ?not to worry though. ?a very reputable mechanic told me about it a couple of years ago. ?i first used it in my v-twin powered motorcycle. ?when i realized this was a decent product i used it in my vehicles. ?not only in the gas tank, but in the crankcase as well to clean out old oil before oil changes. this is easier on the gaskets than motorflush for cars that have a few miles on them. ?this way you do not spring a leak after using it. ;D
 
GM will tell you as well as other car makers that some pinging is normal. I would suspect that you have a little carbon build up and just need a concentrated fuel additive to clean up the valves etc.
I would only burn the 87 octane, higher octane fuel will just draain your pocket. 87 octane has more BTU and that can = more MPG.
As for the crickets around the steering wheel area I would check where the guage cluster and the dash front trim piece meet. I noticed when doing my cluster change out (to Denali) that their is a felt piece stuck to cluster where the dash trim piece and cluster touch. This is right at the bottom of the cluster right in the middle. The two pieces will rub together and the felt showed that it had rubed a lot!
:cool:
 
MrYum,

For the chirping noise have the dealership check the shift cable going to the transmission. Mine was just at the dealer last week for the same chirping sound. It took the dealer 2 visits, but they conqured the problem.
 
Man...what a site! Makes owning the Av even better...if that's possible :B:

Thanks guys...great info..

Z66...Thanks for the additional info on the Mystery Oil. I've actually heard of it before, but was always skeptical...primarily due to the 'snake oil' kinda name ;D That said, I'll do a bit more research on the stuff...I'm online 16 hours a day anyway, so I'll check it out :)

Rnold...hmmm...suppose it's possible things are carboned up a bit. Though, I do tend to drive it pretty hard...run sythetic oil...and never use off brand fuel. But, might not be a bad idea to run some injector cleaner through it. And I do think I'm gonna switch to Unocal fuel for a tank or 2 and see what happens. The truck runs awesome...too good to be pinging under hard load. For a big beast, it sure is fun to drive >:D

Endeavorc...Ah! Now, that's one thing I don't think they've checked yet. Or, if they have...they didn't tell me when they did. And it's actually been in 3 or 4 times for this 'chirping' noise. But, since I can stop the 'chirping' by pulling on the sheet metal behind the kick panel on the driver's side...I guess the question is...where is that cable routed?

In any case...again...great info guys...thanks!

 
Dear avalanche owners I am a Chevrolet Dealer Tech
I am sorry my fellow technicians are so not helpful and give us all a bad name but I am dedicated to cusomer service and if I can help any of you I will just e-mail me and I will do research on your problems My e-mail is GORILLA97@suscom.net But now to answer your pinging issue there is a tsb # 02-06-04-23A
This talks about water intrusion into the rear knock sensor causing a sensor malfunction and also instructs to buid a RTV slicone dam around the sensor This may help you in your ping free quuest
 
Avtech,

Welcome to the club!! :)

I can relate to where you are coming from with the tech comment. I don't think anyone was really trying to bash techs in general, I know I wasn't.

I have worked for several dealers (including one of our site sponsers) over the years in various positions with my last 5 years in parts and the last 3 as a parts manager.

Mind you that I have been out of the business for 4 years.

I can say that most of the techs and dealers(at least in my area) really try to fix the problems. Give them a chance and explain your frustation, most will understand and be willing to help you out.

I also offer my services if someone cannot find the answer or has a parts related question.
 
Hey there AvTech...

This place just keeps getting better and better...now we have Dealer Tech on the boards...Welcome! :B:

I just printed the tsb # you reference and will take it to the dealer at the next oil change. I did fill the truck with Unocal fuel today...too soon to tell if that helped. But, sounds like this is a known issue anyway.

It's an intermittent thing...only occurs under hard load (my foot hard on the gas pedal >:D ). I've got less than 10k on the beast...shouldn't be pinging. And frankly, it's kind of embarassing to blow past someone with this sweet looking rig pinging away...lol.

Oh, and I was by no means bad mouthing the dealer techs either. The guys at my dealer are always courteous and they do try to get it right. Perhaps sometimes they just don't keep up on the latest info.

Anyway...thanks for the info...and again, welcome...I'm sure your input will be greatly appreciated around here :B:
 
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