jktenpro

I started a thread in the GD section with the same title over a week ago. I have wanted to run a second tank of gas through before hitting the dealership, which I have just done. The pinging is still occurring when I initially push it hard. My question here is what testing, scanning etc should be done at the dealership.

tblu92

My experience has been that these DI engines are not prone to pinging--Only with some experimenting with extreme timing I was ever to get it to ping---The VVT system aids in low RPM loads to prevent detonation--IF you car is bone stock and has NOT been tuned
then you have an issue---More than likely a bad sensor somewhere---I am also in Calif where we only have 91 oct premium -----Did you try changing gas stations ???
How many miles ?
Z51 or base model ?
If you have a Z51 dry sump they are prone to sucking up oil via the PCV system--in the air intake tube----If you take off your air intake look inside the tube and around the throttle blade pre blade and post----If it is oily then you may need a catch can that many have done to prevent oil injection--------OIL ingestion will cause detonation !!!!

bob guzzy

On my ride sunday I was burning up the old fuel that was in my car from last oct.

I did notice light pinging earlier in the day before I filled my tank, I thinking it was the old fuel that was kind of flat from sitting that long.

The last tank of fuel last year was from Exxon, whatever their highest octane is called, this time I filled my car with Shell 93.

I didn't notice a ping after my fill, but I did go home shortly after, so I can't say it didn't ping because I really wasn't listing for it

jktenpro

I have a base manual with 10,500 miles and it hasn't been tuned. I have not always used tier 1 gas until the last 3 months, which I've been using Shell 93. When I first heard the pinging about 2 weeks ago(only initially when I accelerate fairly hard with rpm's in between 2 & 3 or higher) I switched to Exxon 93 and have run 2 tanks through with it. I would think by now the new gas would have stopped the pinging and hasn't. There are no codes being shown. I figure something is wrong and was hoping someone knew when I take it in what they should actually be checking for and what tests specifically should be done.

jktenpro

I had a friend tell me there was no oil in the intake, but strange to me is checking the oil on the dipstick when the engine is cold(the oil level is about 5 " above the full line. The oil level is at the full line when checking the level when engine is warm, the correct way, which is all that matters, just thought it was weird to see it so far above that level with engine cold.

tblu92

if YOU HAVE A BASE MODEL












If you have a base model it does NOT have a dry sump system--Dry sump systems often are overfilled--It is strange that your car the level goes up that high when cold---
My only thought on that is on your last oil change they used the wrong oil filter---
Most all GM newer cars utilize an oil filter with a built in check valve---The check valve is there to prevent the oil from dumping back into the pan after the engine is shut off---
K/N filters have both models so you with and without the check valve--make sure whatever brand you have has the built in check valve----
5" above the "full line " could indeed create some oil ingestion and in return some detonation

jktenpro

I went to a local dealership to have the best corvette mechanic from what I've heard, in the area test drive it. He noticed the pinging but since he hasn't heard of this happening with the base corvette he contacted an engineer at Chevy. The engineer had the capability of scanning the engine through this dealership since there were no codes. They said the timing was advancing correctly and everything looked normal. The car was checked at different points through warm up to normal temps. They are determining there is a problem with the fuel. I am having a difficult time with that since I have now run over 4 full tanks with different top tier gas at 93 octane with no change, and I have always used 93.
It only does it again while opening the car up and not under normal conditions. I still think its hurting the engine but I guess at this point will not run it hard(I only seldom do) and hope it eventually disappears.
I wonder by stating its the fuel, if that covers the dealership if anything should happen to the engine as well. Does anyone have any other suggestions on what may be happening that they overlooked.

Higgs Boson

you bought the car new or used?

10mm_

Are you sure it's not something else making the noise?

bob guzzy

I took the tune out of my car, I didn't hear it at all this past sunday, I think the diablo 93 octane tune pushes the timing just a bit too much.

It isn't really drastic just it's a light pinging, as if you ran lower octane fuel.

Next tune I'm going to try the 91 tune.

jktenpro

I bought the car new, the first 10k miles, no detonation. For the last 1500 miles I have heard it. It is a base car and not tuned.
The dealership is agreeing that the metallic ping under hard acceleration is detonation. They claim its the fuel but hard to believe that after changing up fuels and only using 93 octane for 1500 miles before they tested it. I was just hoping there were other ideas to what may be causing it.

bob guzzy

This is how I see this, you reported a problem, they told you it was nothing.

If something big happens, you get to say I told you so, now repair it.

stab1991

Any oil consumption ? How much oil are you down after 1000, 2000 miles?

jktenpro

I hope that's the case, just thought by stating its the fuel they may say its my problem, if it wasn't bad fuel problem wouldn't have occured

jktenpro

No oil consumption over 11k miles. The intake tube was absent of it as well.

tblu92

The knock sensors on these DI engines are more sensitive than ever before on the LS based engines---So pinging is rare---Especially in un tuned---I would venture to say that even on a Silverdo DI engine pinging is a non issue---So if you are getting some audible detonation-- it can be only a couple things--either your gas is bad or your knock sensors are bad----I have tuned many Silverdo trks and GM claims they can run on regular 89 OCT fuel----But all of them pinged on 89 and the dealer told them to run 91 or better fuel---Nvere heard from those customers again--so I assume that that was a simple fix--As far as the C7 goes-- it requires hi oct fuel--from a gas station that doesn't cheat

jktenpro

That's the thing, ever since I have heard it(always used 93) I switched to 4 other top tier stations and have gone 1400 miles now with no change. I am pretty sure its not the gas. My other car has never had pinging using these stations either. Now could the knock sensor be bad and not show a code(no code shown)? Two corvette mechanics say it would show one, and the one that tested everything through a chevy engineer said all was great, timing doing what it should be and that it's the fuel. Its hard to want to do any spirited driving knowing I'm probably hurting the piston with the heat generated. Where does one go when the car has been checked thoroughly, and 5 tanks of gas have been run through it?