Re: 99 z71 chevy spark knocking



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Marty,
The mechanics are partially correct. The computer advances the spark until it detects knock, then IMMEDIATELY retards it to a safe level. By immediately I mean within 1 second, so fast you usually don't even HEAR the knock. I'd run a bottle or two of Chevron Techron thru yer' gas tank (1 bottle treats 12 gallons, so use accordingly) and change out the fuel filter as well. If that doesn't clear it up post back.
Doc
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I have a 99 Z71 also, no problems with what you talk about
My son in-law works at a parts shop that has a Vehicle computer recalibration machine that's hooked up to GM
I went to the following website first to see if there were any updates for the computer in my truck and there was 3 pages of them, I couldn't believe it, the updates ranged from tranny shift to fuel mixture adjustments to pinging to idle problems etc
http://vci.ecomm.gm.com/vci /
Go to the website, enter the VIN # to your truck and it'll search GM's database to see if there are any updates for your vehicle, basically all that happens is the computer is taken out of your truck, hooked up to a computer, your VIN # and specifics are entered in, it basically reformats the computer on your truck and includes all the updates, they re-install your computer, hook another machine up to it, fire the truck up, then the truck engine thinks something is screwy, they do what they call a "case learn" so the crank can get back in sync with everything else, clear out all of the errors out, mine had lots, and done.
I didn't really notice any difference afterwards, I got it done for free, otherwise, I probably wouldn't have bothered if it was going to cost me.
It might be worth looking into for yours if its pinging
Brian
PS, This may be a Canadian site (if it makes a difference), I am from Canada

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