99 5.3 timing

[twobit]

What do you guys think about using a 6 liter timing table in a 99 5.3? The timing in my 99 sux big time. It starts to drop off at 2800 as oppose to 3200 or so. Plus the most timing I ever see is 20, at wot. Looks like the 6L table would be an improvement and a good start for a beginner.
I'm currently running a 180 thermo.

[twobit]

or should I just add say 3 degs to the entire stock table?

[GMCwantsLS1]

With a complete list of mods Farmtruc (Allen) can probally tell you what the timeing should be. He also does tuning!!

[twobit]

My mods are:
LS6 cam
LS1 fans
180 thermo
tm deleted
Volant air box
Gibson muffler
3.90 gears w/G80


I'll probably end up getting Allen to tune it eventually. Just want to play around with it first.

[farmtruc]

The 5.3 has a lot of potential in it, it's just being held back by the pcm tuning. You can safely bump your timing up to 30deg , just make sure you don't have any knock retard.

That ls6 cam just altered your hp curve also, make sure you a/f ratio is around 13.0:1 also. How do you ltrims look, if they are too positive they will make your a/f ratio run a tad rich.

I would increase the timing table like you said but i usually don't do the entire table, there are some negative values in there and that would just make them more negative. increase you table +3 degs on all the fields above 2500 rpms and above .6 gms/cyl. if you don't have any kr, keep increasing it, some engines just like lots of timing,

hope this helps,


allen

[GMCwantsLS1]

Ask and ye shall recieve lol!!!

[twobit]

Thanks! My ltrms are about -1.6 at part throttle. I do occasionally see about 1 degree of knock.
What is considered part throttle, below .6? thx again.

[farmtruc]

Ok, so you're seeing KR at that low of timing, that is not good, besides the mods you have done, what else have you done to affect a/f ratio?
Did you descreen the maf or port the ends, do you have an aftermarket maf?

Usually, KR is the result of a lean condition, most of the time. Did you happen to log your a/f ratio? Log it at cruising speeds and at wot.

We'll eventually get this solved,



allen

[twobit]

I had a descreened maf on but I just put a stock one back on. Ive had it on only one day. Not sure how long it takes the computer to pick it up. The silencer has been cut off the stock intake tube(not sure if that effects air flow) Also have a ram air tube running up to my Volant air box.
Also, I had a vacum leak in my EGR tube which got fixed earlier during the week. When I get the kr my o2s are around .935/.940(rich?) I ran it up to 5k today and got some knock around 4k then it went away went it got to about 45k.
How do you log the a/f ratio with autotap? thx

Clint