Timing and fuel trim

[oleshifty]

My tune hasn't been getting the gas mileage my handheld used to. I emailed nelson and he told me to check the timing/fuel trim. I have no idea what "good" values are. What do ya'll think?




Alright, at idle, timing is about 20* ltrim is about 4.6

At cruising speeds (didn't change much between 50 and 70) timing bounces between 28 and 40*, seems to display 34.5 more then any other number.

At same cruising speeds, ltrim b1 was 6.2, ltrim b2 was 5.4

Whenever WOT, ltrim b1 is 5.4, ltrim b2 is 6.2, and timing is usually between 21.5 and 24 (seems to change lil depending on rpm/ outside temp/etc)


These numbers are all from my aeroforce interceptor.

[pl4yboy]

ltrims seem high to me.

[oleshifty]

is that a simple tuning thing? or is it possible something else is wrong (though I doubt it, gas mileage seemed to drop pretty much overnight...well after a week when I finally stopped flooring it all the time lol)

[pl4yboy]

It's a tuning issue. What does your AFR look like?

[oleshifty]

don't have the wideband yet


The aeroforce has o2 readouts, but those go all over the place. I have a autometer narrowband gauge, tempted to hook it up to the front 02s until I can afford the wideband (didn't think i'd need it until the cam/heads go in)

[pl4yboy]

I'd have a look at your AFR when you can.

[farmtruc]

Those values aren't high. The high limit is 25+, it has plenty of room for adjustment before it sets a code.

Get in any stock vehicle and look at the ltrims, they will be between 0 and +10.
The ltrims are there to correct for conditions that are not controllable.
One day they may be negative, the other day positive.

So many things will affect ltrims: fuel pump, filter, injectors, maf, fuel, o2's, etc.

If I had the truck here (which it will be soon), then we'll tune until they are -5 to 0, but for any truck with his mods, it's perfectly acceptable.

[oleshifty]

you'll have it there? Allen, are you stealing my truck? I'm in IL, don't think that'll be happening, unless I win the lottery and can afford a turbo lol

[farmtruc]

you'll have it there? Allen, are you stealing my truck? I'm in IL, don't think that'll be happening, unless I win the lottery and can afford a turbo lol

haha, wrong truck sorry, but still come on down, lol

[pl4yboy]

If you want them at -5 to 0, then I'd say +5 is high. I was just comparing to my logs and based on mine, +5 is high.