06MonteSS

after driving and logging for a week, and based on the log numbers - I needed to make another minor adjustment to my tune yesterday... I'm using the Diablo No DOD performance tune - then I set the injector slope to -6 and the WOT PE to +2 across both RPM ranges. Then I reset all of the "learning" parameters by disconnecting the neg. battery cable for about 20-30 mins.

I took a couple of short drives yesterday - and this morning I figured I would do a log on my way to work. My ltft's look good, and lock at 0 at WOT. Based on the O2 (.86-.88) and AFR (12.3-12.6), I can bump up the PE to +4.

Now, here's the puzzler... while the log shows the AFR at 12.xx at WOT, the reading on the handheld's screen shows 17.xx !!!!

What gives??

Thanks!

Sneakyws6

Have you called Diablo and talked to Mike or Johan yet?

I will be honest with you there are not many people on this board with experience with the newer Diablo tuner so I dont know how to help you with this as the Predator I have for my 01 Formula does not data log like the 04+ LS1/LS2 tuner does.

SSpdDmon

iTrader: (10)

Do you have a wideband O2 sensor hooked up?

06MonteSS

I posted on another forum and Mike responded this morning, letting me know that he was going to see what he could find out from Johan - so I'm waiting to hear back from him - hopefully tomorrow.


no I don't... I know, I know....

but until I can afford a dyno tune, I'm going by the AFR and NB O2 numbers.

06MonteSS

whelp, I checked it again this morning on my way into work, and it's not a fluke... at WOT, on-screen still shows 17.4x+, while the actual log is showing 12.5 - 12.2.

I'm running the Diablo No DOD tune, with a -6 injector slope and now +3 PE -- and all numbers in the LOG look good... at WOT, the ltft locks at 0, the O2 is reading 88x, and the AFR is 12.5 - 12.2.

and when I made adjustments to the canned tune, I ADDED to the PE table across both RPM ranges (+3), making it richer - so there's no way it would be going up to 17+ (waaaaaay too lean - BOOM!).

sprayjunkie

Responded on the GTO board...

06MonteSS

so the log file seen in the viewer and csv file is correct?? cool!! Thanks Mike!!

WHEW!!

SSpdDmon

iTrader: (10)

I'd target .900mV across the board (assuming you're still on stock manifolds) just to be safe. But, I still think the NBO2's are junk for determining WOT fueling. The AFR the log is spitting out must be commanded AFR. I don't understand how they could turn NBO2 mV's into an AFR that actually makes sense on a consistent basis.

06MonteSS

yeah, everything is stock except for a CAI...

If it was a "commanded" AFR, wouldn't it be the same all the time, since it was commanding a specific ratio? After I reset the "learning" parameters by removing the neg. battery cable, I've seen the AFR fluctuate even when sitting at idle -- fluctuating between 14.xx and 16.xx until it finally got to 14.75 eventually.

I'll have to check the logging parameters on my way home, but I believe "Commanded Air Fuel Ratio" is a totally separate one that I can choose to log... the one I log is the normal "Air Fuel Ratio". Is this correct Mike??

And for WOT - by adding more fuel to the PE table to get the O2 closer to .900, won't that make my AFR go down to low 12's, high 11's (richer)?? Shouldn't the WOT AFR be about 12.8-12.9?? Is this correct Mike??

Thanks for the help everyone!!!

sprayjunkie

The parameter you are viewing is actually an 'inferred A/F ratio' determined from the O2s and the fuel trims. each vehicle will have its own swwet spot where it wants the A/F ratio to be.

SSpdDmon

iTrader: (10)

Higher mV's do equal lower AFR's. But what I'm getting at is, just because it says .880 mV's = 12.x AFR doesn't mean that's what your actually running. You need a WBO2 for that.

06MonteSS

I agree... but until I can get to a dyno and/or get a wideband, this is all I got...

At WOT -- I'm at .88x mV's now at +3 in the PE ranges... and my ltft's look good (0 to -.78) with my inj. slope set to -6... so I shall bump up the PE to +4 in both RPM ranges and see how much closer to .900 that gets me.

thanks!

06MonteSS

Hmmm... or even leave it at +3 for the PE ranges, and only go -5 on injector slope instead of the -6 it's at now - that should work too...

SSpdDmon

iTrader: (10)

You say injector slope....how is it being changed when you go from 0 to a negative or positive number?

06MonteSS

if I go negative on slope, it brings my fuel trims down - making it "richer" -- so no additional fuel gets added (maybe even take some out), so my trims trims go down/negative. This is what I did to get my trims down to 0 and slightly negative. I am getting anywhere between -1.56 and +1.56 with my slope at -5... and even though I'm in V8 mode all the time now (disabled DOD), my mileage even went up 2-3 mpg... presumable because I changed the slope ("size") so it's not dumping/adding in as much fuel as it was at the stock setting.

If I go positive, it makes my trims go up - making it "leaner" - so more fuel gets added and my trims go positive. When the slope was at 0 (stock setting), my trims were around +10 - meaning it was too lean and it was adding that much more fuel.

SSpdDmon

iTrader: (10)

I wasn't sure if it was moving the entire injector table (ie all injector values increase by the same, fixed amount) or just re-adjusting the slope to something steeper/flatter (ie increasing/decreasing all values by a percentage of their existing value).

06MonteSS

the adjustments in the Predator are all percentages... i.e. if the ltft's were reading +6.xx, ideally you'd be able to adjust the injector slope to -6% to zero them out...

the same goes for the PE ranges... increase/decrease by percentage... i.e. if you went -6% on injector slope, ideally you should be able to go +6% in the PE ranges...

SSpdDmon

iTrader: (10)

I see...so then you ideally want to use the injector slope adjustments to get fueling close enough to where part throttle (closed loop) is dialed in. Then, you can dial in your WOT fueling with the PE adjustment. It's a little crude, but nice adjustability for a handheld. So, you're on the right track adjusting the injector slope based on fuel trims. Once you get access to a WBO2, then you can finish it off in the PE table.

06MonteSS

correct, to all the above...