i bought a used 5.3 chevy truck (2005) when i go WOT it pings, even on 93 octane. i put a scanner on it and it shows to be at 30 degrees timing. anyone know what to shoot for on remedying the problem. no ses light and no codes showing to be in the ecm.

 

Check the fuel psi, B4 you alter the tune.

 

thank you but it is on 60 psi, i checked that 1st. the screen is off the maf, would that have anything to make it go that high?

 

anyone?

 

But, is the fp holding @WOT?

 

30* of timing seems like too much. My stock 2011 5.3 runs about 23.5 maximum. Might try lower your advance.

 

I am assuming you have stock compression?
I would say you are too lean.

 

That is too much timing for that year truck. probably wise to get it lowered.

 

It would probably make it run lean on throttle transitions, which can cause pinging. Try a stock screened maf before mucking with tuning.

 

knock attack should be removing timing to compensate if it is picking up detonation. You should be seeing a drastic decrease in timing unless you altered the knock learn or attack tables. I would make sure you either use a stock maf of retune to the new maf. It sounds like you have a problem with fueling.

 

I would first look for signs of tampering. Such as IAT
trickers, ported MAF, anything that will lie about air
mass.

Then scan in ping-prone regions of operation for any
misfiring that points to an individual cylinder lean.

30 degrees is not crazy for low compression, I would
look at fueling (which may be an air mass fidelity deal)
first. Maybe not helping, but not totally nuts for stock.
What is your WOT AFR saying?

 

It seems odd that a 2005 pickup in stock form would ping on 93 octane. One sometimes overlooked thing to consider is that the spark plugs in modern ignition systems can be a part of knock sensing and supression. It would be a long shot, but inexpensive to check - see if it has the correct plugs in place, and not some super low-impedence racing plug or something. A non-projected tip (where one is required) can also contribute to detonation by shrouding the flame front.