Timing and fuel trim

[farmtruc]

Ive always heard that ls motors love 13.1 far in pe mode. Is that not right?

ya, i'd say that's a good a/f to shoot for. what do you have that ls3 set at in your sig?

[o2camaross]

It's a stock tune other than a few Dtc's disabled and tm removed. I want to get a wideband before I start tuning it

[oleshifty]

Got my wideband in today.... idle/ cruising I'm around 13.6-13.8 at wot, 11.9-12.3


thoughts?

[farmtruc]

cruising looks fine, as long as cruising a/f ratio is between 13.5 and 15.0 it's ok, it's hard to get an exact on cruising because it's going to be up and down constantly.

wot is a tad rich, we'll need to lean it out a little.

[Pavetim]

If he's getting good number of cell counts it will average it out and 13.5 is rich at cruise, you only really need richer afr when in PE mode. You can safely go to 15 at a cruise then when you hit PE mode use 13.1, and 12.7 at WOT. Best bet is to tune using your stock O2 sensors and then you will need a Wide band to tune your PE/WOT. You want your LTFT's in the -5 to 0 range, if your in the + that means your lean and it will carry over the correction into PE so will throw off your tune. But tuning using LTFT is actually pretty easy, and pretty accurate using stock Narrowbands.

[George C]

id rather have a +1 or + 2 then having a rich condition of -3

in cruise mode timing should be high 40s to low 50s with no load, slight load timing decreases but should still be high 30s to low 40s

keep working at it till the MAF is next to zero for error and fuel trims are around 0 thru +3

this is where your mpg will come around at. not enough timing will also increase EGTs!!!!!!!!!!!

[Pavetim]

If you have negative LTFT when you hit PE mode your O2's will lock and it will not correct. You will be going strictly off your commanded, VE table and MAF if your using it. If you have positive LTFT when you hit PE mode it will carry over into PE mode and sometimes can be tricky nailing it down because you will get corrections in PE mode if your positive on your ltft. You can have negative LTFT thats no biggie, don't mean your rich because it will correct to what you have set for stoich anyways. But you tune it the way you want everybody is different. Thats why you work your VE table to get between 0 and -5 but as close to 0 is ideal. All mine are between 0 and -2.