why are my stft's staying so lean
 

I posted this over in the HPtuners forum also....but people here tend to be more helpful.
lq9 stock bottom end, ls3 heads,intake and injectors, 92mm nick Williams tb, 85mm Delphi MAF, spectra cai, t56. PSI conversion harness, and start up tune on 02 silverado ECM. Starts great...idles great...runs very lean. The only thing i have done to the tune is set the injector flow from the 42lb/hr at 58psi to my 65psi fuel rail pressure. Looks like the engine temp comes up real fast from my lean stft's.....do you think this is from a vacuum leak? When i raise the rpm to 2000 notice the trims come down?? Or is my tune just so far out of wack???

Attachment 459298

Check for vacuum leaks. Post up your tune.

Post tune. I had a TR224 cam before so I can check with previous tunes to see how that goes for you. To be honest, my VE tune for my car from LS1 TR224 to 230/5.3 combo to 6.2L + 5.3 to LS3 did NOT vary the VE tune down low sub 3k rpm by much at all.

Thanks for such quick responses! The cam is a LSR273 comp cam 223/232
.610/.617 112LSA.

Current tune in ecm:

Attachment 459308

Your ve table looks fine to me, Why is your timing so low? Your commanding 11.7 Afr at wot and only have around 5* of timing. Are your spraying the car? Who tuned it?

Also I looked back at your scan file, Go under settings on the histogram and increase the cell hits required so you don't get so much garbage data

Are you sure this is actual lean and not a O2 sensor issue?

Sure that there is no misfiring cylinder to jack the readings?

Very low timing might leave a lot of "unburned air" in the
exhaust.

OK...thank you....i'll look at the timing and set the histogram cell hits. Pretty new to HPtuners and willing to learn, but the learning curve is pretty steep and summer will be over if i try and do it alone. Really appreciate the help!

The timing commanded versus the ve tables are very off. I'm thinking, how can you ask for this much fuel yet have so little timing and still be lean?

O2 possibly wrong? Your nose near the pipe can smell when its off as well especially when its this off...

I think you need to start with that injector data first.

[QUOTE=jimmyblue;18309034]Are you sure this is actual lean and not a O2 sensor issue?

Sure that there is no misfiring cylinder to jack the readings?

Very low timing might leave a lot of "unburned air" in the

exhaust.[/QUOTE

New 02 sensors..and the engine temp rises so quickly indicating possible lean condition. How can i detect a misfire in cylinder with my scanner...wouldn't i get a code?

Yes..came with the top end i bought.

Start your scan log before starting the car, and open the DTC option. You will then be able to monitor any trouble codes the car has It will update every few seconds with data.

Maybe my fuel pressure gauge is off? It says 65 psi so i increased my injectors for the extra psi. I have a corvette 58 psi regulator on the efi from tank inc but my pressure regulator says 65. But wouldn't this change slow down the amount of fuel? The car does smell rich...i can smell the unburnt fuel.

I tried that and it wasn't throwing any codes...man this thing is driving me crazy....anyway off to work.

I would start with normal LS3 scaled injector data. There are plenty of tunes out there which have it with LS3 swaps.

Move to put in your default VE table and standard timing. Less fuel more spark, see if you can get it to burn properly.

Monitor fuel pressure after it is warmed up, I always noted my FP was a few PSI up when cold and then settled to 58 PSI once warm.

THANKS for the help! I'm still at work and will make the changes when I get home this afternoon. I'll do another scan and see what we get.

Who did that start up tune for you?[/QUOTE]

PSI Conversions...I bought the harness from them, ecm and 85mm Delphi MAF. Could the spark plugs I have in there be a problem? It was for a LS swap into my 69 Camaro:

http://i302.photobucket.com/albums/n...E/DSC_6885.jpg

would i be better off pulling a base tune from an ls2 engine...say 2005 corvette from the HPtuners repository?

I would work off the spark/ve tables of a ls2 based vette, or the ls3. Grab the MAF settings from the truck 85maf. I used that as my base and tuned on dyno later with very little change to most of the maf table.

Thanks bozzhawg and SladeX...i'll fix the injectors to the spread sheet you attached then i'll find the MAF table from a 85mm truck and spark/ve table from a 08 vette since those are what the heads are from...just need to convert pressure to kpa. Damn work...getting in the way of my tuning:judge: