I had a custom tune done on this truck back in the summer and it's tune for 93 octane. I'll take it back to get it tweaked ever so slightly to address this detonation issue my curiosity lies in what is the probable cause of detonation.

During the summer at WOT or close to WOT it would just barely ping every now and then when it was really hot out 100-105 and it was more noticeable when it had a load on it.

Once weather cooled off it went away almost completely but last night and today it got flat cold here it was 25 this morning and fully warmed up and nailed it getting up on the highway and for a brief second it started detonating like a 6.5 diesel as soon as I lifted just a tad it went away once on highway tried it again and same thing and it's never done it that bad.

Does it sound like a simple timing too hot and it needs to be tweaked or a possible fueling and timing issue. I haven't had a chance or time to stick my tech 2 on it and look at kr or any other reading to see WTF is going on with it.

Truck has a volant/stone stock on the motor exhaust manifolds cats.

 

It could be a little lean and little to much timing. On trucks and heavy cars with the gas we have with ethanol in it I find they seem to like 12.5-12.6 alot better than 12.9. I know 12.8, 12.9 isnt dangerous lean or anything but they always dont run the best that lean from what I seen. The newer 08+ also like alot lower timing than the 07 and older ones did. Of course without seeing the tune or a data log I am just speculating but I see both of those things pretty often when doing re-tunes especially in trucks.

 

I've got the dyno sheet on it and it has the WB readings on it I'll have to go take a look at it and see what the target was. It did not do it right after the tune it acts up when we have extremes of outdoor temp be it100-115 or 40 and under. get above those temps and quiet as a church mouse.

 

seems like you got a seasonal tune.


if AFR error was on point, +-2 %, then IAT multipliers would (most of the time) compensate for it and wouldn't matter if its "extremely" hot or cold.

the AFR on the dyno sheet might seem proper, but could be achieved through "power enrichment table raping", once the weather changes, the AFR will always fluctuate, either leaner or richer. Seems like the heat soak is leaning your mixture out and is pinging.

 

The tune is very good powerwise and fuel economy wise. I've been going to get HP tuners for tweaking the little things cause it is such a PITA to take the truck back 3 hours 1 way to get little things mainly tranny wise touched up.
I have a pretty solid understanding of tuning and what does what where and how for the most part I've just always let the pros do it due to the amount of time and getting stuff exact.

Where would be the first places to start looking on my own to see about getting this little gremlin kicked to the curb once I get HP which I think will be ordered in next few minutes.

 

You're going to need to order a wideband also to see what your a/f is doing. Download the tune and compare to stock to see what's been changed. Then go do a data log and check your timing, knock retard and a/f.

 

well then if you need any help and you're near the houston, tx area then let me know i can help, maybe just invite me to a beer

if you are further up north i believe lsx power tuning is in austin or college station not sure and im sure he can help

but get a wideband

 

The iat table adds timing below 40 degrees or so. Zero those values out and the pinging I'm cold weather should go away.

 

post up your tune with log and let me take a look at it!

 

Correct me if I'm wrong here but this table would be useful on the stock tune since they put hardly any timing in it. But since we are talking a custom tune here and I had it programmed to not leave much on the table if this table has not been zeroed it would def be thee cause of cold weather spark knock like I am having due to being waay over advanced.