Modifying a custom tune

[flybyu]

I was inquiring about modifying a custom tune.
Some of the items listed (Fans, Speedlimit) I can see the changes that have
been made plus or minus from the baseline (which you call Zero).
But in the "Power Enrichment" or the "Spark" at all levels they are set to Zero, does that mean none have been adjusted?
The injector slope has been changed and reduced and that can be viewed.
Do you not adjust any Spark or Power Enrichement in the custom tune file that I was sent?


Mods:
1999 Vette, 5.7L M6, Callaway Intake, Kooks 1.75 Headers, Kooks Cat'd X Pipe, Corsa Pace Car Pro Exhaust

Unit:
U7198, Bios ver 6.01, Hardware 1.01, Software ver 2.13

[mikel]

Those parameters default to '0' so you can still have the full range of adjustment in the tool, whether or not those parameters were changed.

Thanks

[flybyu]

Great, thanks for the fast reply.

[flybyu]

I managed to scan the Vette on the Hwy the other day after uploading to the car the custom Diablo tune from Mike.
Here is a quick scan with my LS1M hand held palm scannner, it can be viewed below at Scandepot.

http://www.scandepot.net/viewscan.php?pk=3766

The LFT1 and LFT2 fuel trims look a bit negative does that mean I can adjust the Injector slope a bit more posative by 2-3%
and see who it runs?
I am currently running 91 octane but we have 94 octane here and might switch, will this effect the readings also?
Any input would be appreciated, thanks.

1999 Vette, 5.7L M6, Callaway Intake, Kooks 1.75 Headers, Kooks Cat'd X Pipe, Corsa Pace Car Pro Exhaust

Diablo Predator U7198, Bios ver 6.01, Hardware 1.01, Software ver 2.13

[06MonteSS]

you'll get more power/ooomph! using the 93 octane tune and 94 octane fuel...

your average ltft's are -3.... so you can set your injector slope to +3%....

[flybyu]

Yes I figured about 3%, now with 94 octane instead of 91 octane will that change things with the LTF's?

P.S. Great looking ride!

[06MonteSS]

no, it shouldn't change your ltft's/amount of fueling... you'll still be spraying the same amount of fuel, just a higher octane.

p.s. Thanks!!

[flybyu]

I managed to adjust my Injector Slope by 3% and logged the car on the Hwy
on the way home. The LFT's seem to be at a +3.9 average now?
I thought increasing by 3% would get them closer to zero, but they seem over in the posative now.

I decided to go look at the car again tonight so modified the custom tune
again and the Injector slope said 3%, I guess it remembers what was
programmed previously.
I adjusted it back by 2% (so only 1% over original) and then flashed, drove
the car for 30+ min and monitored the LTF's they are now at 0.8 to 1.6
each respectivly.

So I dont understand why going back 2% did not bring it below zero?
When it said 3% and I flashed again did it add an additional 3% if you flash again each time.
Or does it just remeber the value? If that makes sense.

[flybyu]

Anyone?

I might just install the Diablo tune from Mike again and knock it up by 1% at a time and see what happens.

[johan]

Did you let the trims mature? It takes at least a good 45min for the trims to fully learn.

[flybyu]

Ok thanks, I did not know that, drove it for about 30 min, when I am out tomorrow will log again after a few hours and see how she is doing. Thanks

There is alot of usefull information here that is not in the manuals. Would be nice to have a in depth sticky on this stuff.
It would help relieve you guys from answers so many questions that are not detailed anywhere.

[Whiterock1]

So, we ideally want a LTFT of zero, and if it is positive, bring it in by going positive roughly the same % on the injector slope. What exactly is the value of zero? I assume an AFR of 13 or so? Does this vary by car? ('06 Vette, 7194 in my case) Are the nominal values in the ECU the same in all cars, or do they vary in some range? Is it possible to have a car that already has values of zero or negative? Inquiring minds...

Mike

[06MonteSS]

There is alot of usefull information here that is not in the manuals. Would be nice to have a in depth sticky on this stuff.
It would help relieve you guys from answers so many questions that are not detailed anywhere.

there are stickies at the top of the Predator GM forum...

http://diablosport.com/index.php?name=P ... opic&t=917

http://diablosport.com/index.php?name=P ... pic&t=1145

[06MonteSS]

So, we ideally want a LTFT of zero, and if it is positive, bring it in by going positive roughly the same % on the injector slope. What exactly is the value of zero? I assume an AFR of 13 or so? Does this vary by car? ('06 Vette, 7194 in my case) Are the nominal values in the ECU the same in all cars, or do they vary in some range? Is it possible to have a car that already has values of zero or negative? Inquiring minds...

Mike

no... if your ltft's are positive, you bring it down and get it inline by going negative on injector slope. If you go more positive on slope as you mentioned in your post, you will be making the car more lean... going negative on slope makes it more rich.

If your ltft's are negative, that means your car is running rich and the ECM is subtracting that much fuel.

If your ltft's are positive, that means your car is running lean and the ECM is adding that much fuel.

If you go negative on injector slope, it tells the ECM that your injectors are smaller and to spray more fuel.

If you go positive on injector slope, it tells the ECM that your injectors are bigger and to spray less fuel.

At normal cruise/driving, the AFR will always be stoich at 14.75 - since the ECM constantly adjusts the fueling to keep it at this value - that's what the fuel trims are for.

[flybyu]

Thanks for the informantion, good writeup.
Also from reading if I set the Injector Slope more posative by 3% then the PE must go opposite by the approximate same amount.

What do you actually run your car at, on the posative side?
I know a bit lean is better for HP but can be dangerous if you get pre-detonation and KR robs HP.