2015 Sierra- rattle when accelerating

[Forstt]

Hey guys,

I've been running the 87 tune, with DOD off, TQ on and throttle booster set at 15%. I've noticed that I'm getting this rattle/Chatter sound that happens only for a second when pressing on the accelerator. I've been researching the cause and most are saying that it could be "Pre-Ignition" spark knock. I'm concerned this could be a timing issue with the tune.. I've been running BP and Sonoco 87 OCT. fuel. Can you please provide thoughts? What else could it be?

I have a KN air filter and Magnaflow exhaust. I checked the exhaust and Cats and everything is good.

Thanks

[gregory]

Almost sure you got detonation issue. Try to up grade your octane rating and stay with Sunoco and see if it stops. If it does it may be due to the adjustment on throttle boost which may advance your timing a bit thus requiring more octane. I run 93 octane with a cmr custom tune for high octane and never get the dreaded clatter. you can also run just the tune without altering the tune and clatter should stop, I have run that tune on regular and never had any valve clatter even climbing a very steep bridge I drive daily. Good luck and let us know what you find.

[06MonteSS]

I would use at least 89 octane...

and Make sure you are using GOOD gas, it makes a difference... mobil, exxon, sunoco, amoco, bp, chevron are best brands to use, with mobil and exxon being the best.

NEVER use Shell, costco/bj's, mom-n-pop, or no-name brands, as it's crap gas that tends to cause a lot of knock retard and less performance/mpg...

[Forstt]

I'll try upgrading to higher octane fuel and will keep everyone posted. Is there any possibility that the noise is coming from the torque converter? I'm starting to think the sound may be mechanical. I changed the tune yesterday to the MPG tune. I heard the same chatter/rattle sound when I pressed on the gas when moving 15-20 mph. Rattle sound was heard for 1-2 second max. I cant get it to replicate consistently. Thoughts?

[gregory]

doubt it sounds like crap gas for sure now. High octane good gas bet it disappears that will confirm.