Injector Slope?

[The Hog]

I was dicking around with my little diablo programmer for the caddy today and I noticed that one of the parameters I can change is injector slope? WTF is that?

[rrussell]

Injector slope is a term used when you put a bigger injector in or a smaller ones.
It usually has a correction in +/- %.

So if you did a exhaust mod or something that would need more fuel you could add a bigger injector and then trim it down by using the injector slope for idle and the transition in your lower rpm's.

Other wise you would have a overly rich condition because of the new larger injectors.

[The Hog]

So I am guessing that if you were to graph out the entire fuel map you would be increasing or decreasing the slope of that graphed line essentially? So, in theory, I could use that same correction factor to richen or lean out the overall fuel curve as well?

Essentially the only parameters I can change for fuel are WOT above and blow 4k RPM and the injector slope so im just trying to figure out exactly what I can do with this thing. So far changing fuel around a bit has made little differenct but i've added a bunch of timing which seems to perk things up a lot without ever kicking in any knock retard.

[rrussell]

If you get creative enough you could do what I'm doing and have a semi wet/dry system. Add some of your nitrous fuel thru the injector.:P

[The Hog]

Ohhh dear god that scares me. You will never SEE nitrous on that car (it hurts engines ya know). ;-)

[trbo355]

Does the Diablo tell you what the actual WOT timing is? They always seem to perk up with timing advance. The older LS1 engines can be happiest at 28 deg. total but the newer ones are kind of hit and miss but usually land around 24-26 before KR rears it's ugly head. If it lets you scan live data, try to get the O2 to read around 880 Mv at WOT and you will be pretty good on the fuel trim. They are usually rich from the factory. Oh yeah, if you are too hot on timing and you see a good amount of KR, the factory ECM will revert to the low octane table and dump about 6 deg. timing. This is one instance where putting in some high octane gas actually can make the car go faster bone stock!

[The Hog]

It will give you real time timing so if you stab the throttle and happen to have time to stare down at the tuner in your lap you can view it. I tossed katie in the passenger seat and made her watch for the knock retard kicking in.

It will give me o2 voltage but I didn't really know what to look for so I just didn't worry about that part lol.

I'll have to play around with the fuel side and watch those o2 readings, its pretty slick it will give me voltage from all 4. The timing I threw in today sure perked things up a lot :-)

[trbo355]

Sweet! Seems like most stuff responds to an extra 3-4 deg. timing bump. Makes sense when you figure GM engineered the car to be able to survive in the desert at 110 deg. Dont worry about rear O2 readings at all. They just monitor catalyst efficiency and will prob. read a lower Mv than the fronts. B1S1 and B2S1 will tell the real story. As a rough guide, 950Mv is pretty fat and 800Mv is pretty lean. Its not cut and dried since the sensor aint in it's intended operating range of real useful data but it's still fairly repeatable from car to car. When the hell is GM going to start using wideband on these things!!! It would make life so much easier.

[The Hog]

Mine does have the widebands in it (bosch LMU). woot.

[twotons]

Hallelujah! Bout time GM got with the program. In that case, i have NO IDEA what your O2 voltage should read! LOL

[twotons]

the predator has a live data loger built in too, have you found that yet, shows WOT timing, fuel , knock, and buch of other usefull imfo. anyway i thought i would throw that in.

[The Hog]

as I remember the o2's were somewhere in the mid 800 range. I have heard that they have that datalog feature but have not found it yet. I suppose katie would appreciate it if I figured it out so she doesn't have to ride shotgun all the time lol

[twotons]

I believe it is in the tunning section , not positive.

[trbo355]

Hallelujah! Bout time GM got with the program. In that case, i have NO IDEA what your O2 voltage should read! LOL
Hmmmm, i see that i posted at work under Brian's name again.
Dammit. :)

[The Hog]

Well good to see you guys are getting a lot done over there lol. Speaking of which, I still need ball joints swapped out on the JDM Expedition.