This post may show my ignorance, but I have little experience with engine work so bare with me. I keep reading about our computers retarding the ignition to avoid spark knock. Well here's the thing, since day 1 on my truck I have never been able to run any less than 93 octane. At 91 or lower (especially 87) during WOT above 4K rpm I get this God aweful sound from under the hood. It sounds like if you put a pebble in a tin can and shook it violently.

Does that sound like spark knock to you? If it is should I get my truck checked out and/or sensors replaced? If not what else could it be? The truck info is in the sig, and it has never thrown a code or have had any trouble other than this.

 

That does indeed sound like pinging/knocking. I'd take it into a good dealer to check it out.

Did you possibly put some crap/nasty gas into it (oftentimes carbon buildup can cause this situation.)? Anyway get the situation resolved, your pistons will thank you for it.

ps, it doesn't have any programmer type tuning on it does it? If it does than the advanced timing cause by said tuning could be causing the knocking/pinging/preignition that you might be hearing.

Then again, maybe you just have the piston slap that so many of these LS1-type motors have.

 

I would be afraid to let anyone touch that PCM based on that ET.Keep running good fuel and smoke a few Hemis and thrash some 4.8s that have $2k worth of mods done.

 

03 silvy - No programmer yet, but that was going to be my first mod in order to kill the speed limiter. However I certainly don't want it advancing the timing any more than it already is. I'm pretty sure it's not bad gas because it did it a couple times when new on 87, then again this past weekend when I was feeling cheap on a road trip.

Gonzo, I agree. I don't want anything retarding that timing unless it's detrimental to the engine as is. I'll just keep to the 93 octane.

I have a lap top so I suppose I could get edit, but I'm a little cheap for that and I don't plan on any serious mods. Does anyone know if any of the hand held programmers will allow you to drop the speed limiter and change shift points without screwing with the timing?

 

HPPIII will let you do that. I'm looking into getting EDIT really soon...and I have another local guy that might go in on it.

You mind sharing a cable?