roland1

So I bought hp tuners and started reading. and reading. and reading...

I enlisted the help of 6l80etuning.com to help me get my 6L80e tuned properly. And the fella who runs the site has been helping me with my tunes.

hes managed to get the maf scaled more accurately. The last tune apparently was a bit skewed. My commanded AFR was changed to like 9 to get it to run an actual 11.5 afr. Im still working on that concept of how that all happened.


the specs of the truck are...

13' rcsb 4x4 sierra.

Thompson forged 370. ARP head bolts and ls9 gaskets.

226/232/ .578/.587 112+3 lsa so three degrees advance ground in, right?

10.8:1 compression.

trick stage 3 kit 76mm.

14 gph meth nozzle.

60lb injectors - theyre barely breaking the 55% inj duty cycle at wot.

94 octane fuel.


heres how my tune and logs looked from a third gear pull...

around 17.5-18 degrees timing above 4500rpm all the way to 6000rpm.

6.50 psi boost. and meth.

I had 1 degree of knock retard at about 4450 rpm. but that's it.



heres something interesting I noticed though.

my plx WIDEBAND @ wot was reading 10 AFR. I originally was running 4.75 lbs boost and it was at 10 AFR. that's when I figured I could add some more air to this thing and turned up the boost.

enter 6.50 psi...AFR was still at 10. I was expecting it to lean out a bit.


Well it turns out my afr gauge reads from 10-20AFR so I am infact richer than 10, somewhere in the 9 probably, this is even at 6psi

now heres my question....

ive taken 2 degrees of spark advance out of the whole table. so I should be around 16 degrees of timing.

and put in the 9 psi waste gate spring.



I know everyone says " with high compression and boost your tuning window shrinks"

but what EXACTLY does that mean??

Should I just keep looking for Knock retard?

What Im hoping to see is my AFR lean out to 10.5 or so.

What else should I be looking for to know that im in the danger zone and should lower the boost and timing?


Another debate is boost vs timing, what nets you more power.

The truck felt great with 18 degrees of timing and 6lbs boost. it felt great at 4.5 lbs boost too. But will it be even greater at a little less timing and more boost?





Hopefully some experienced tuners will chime in and give me some advice here.

attached is my logs and tune. the log is 6lbs boost and 14gph nozzle and 18 or so degrees of timing.

roland1

the truck didn't like the 9lb spring. and doesn't seem to like the 14 gph meth nozzle. the throttle is all broken up when I go wot.

and there was spots on my spark map in the log where it pulled 10 degrees out, howver nothing pulled out in the KR map in the logs....weirddd...

im gonna go back to 6lbs and a bit of timing for now.


dyno time is booked for Wednesday morning so you filthy heathens will have some dyno vids to ogle over.

oakley6575

iTrader: (5)

Is this a MAF tune or SD? I think you are going about this all wrong. You don't increase the boost to lean it out.. You need to decide on how much boost you are going to run and tune it correctly at that point. You are playing with fire right now. If your AFR is in the 9's, something bad is going to happen very soon Being too rich can be just as bad as being too lean.

BTW, more boost will make more power that more timing... every time. Don't be so agressive with the timing, especially if your fueling isn't on point. Get fuel correct first, then play with timing.

roland1

Without the Meth my AFR is 11.2-11.5

When the Meth comes on that's when the AFR Richens up to below 10. So it could likely be a Meth tuning thing.

That's why I thought adding some air would be okay. I guess that's not the case?

oakley6575

iTrader: (5)

Again, is this a MAF tune or SD.

You need to tune for the meth... So you need to log when the meth comes on and see where it becomes rich. Then take fuel out of that area in the tune.

roland1

Its a maf tune. And I'm about 11,200 kHz at wot.

Maf goes to 15 000 I think?

oakley6575

iTrader: (5)

Yea so you need to decrease the values wherever your going rich in the MAF table. There are a ton of good write ups and how to's on hpt forum. I would suggest you get reading over there before you hurt something

roland1

So the maf isn't scaled well enough. I'll look into this.

roland1

Even if my stfts are within 2% of zero?

smokeshow

iTrader: (16)

More boost is always better than more timing if you have to choose between the two. I wouldn't say that means run maximum boost and like 5 degrees of timing... But if you can add 1psi and take 2 degrees out, I'd opt for the extra air.