WOT AFR Adjustment

[PlumCrazyDaytona]

Current AFR is 11, would like to get it to 12. How much should I remove 1,2 percent. I dont want to be spending all nite trying to get it dialed in.....any suggestions?

[brandy16]

Why are you trying to get to 12 to 1. Thats way rich. 14.1 is where you need to be. Take away some fuel and check AFR again.

[Mike_Levy]

No, he's got it right. Hemi's make best power at around 12:1 (low 12's).

However, unless its being measured with a wideband, its not accurate. You can't tune with the stock narrowband O2s.

[PlumCrazyDaytona]

I do have a wideband, I will start tweaking tomorrow in one percent increments. Prolly will need to have my tuner get it the rest of the way dialed in. I just gotta see how much being this rich is leaving on the table horsepower wise

[dnar]

Checkout the fuel tables I posted a while back. http://www.diablosport.com/index.php?na ... ic&t=27915

To get from 11:1 to a more ideal 12.15:1 you need a fuel adjustment of -9.5%.

[PlumCrazyDaytona]

that is awesome thank you!!!!

[PlumCrazyDaytona]

got it dialed in at roughly 12.2!!

[dnar]

Cool. How close was the table?

[ChaoticMN]

Interesting thing, my tuner set me up at 11:1 AFR also. I leaned it out about 5 % No improvements were noticed but I'm going to view the data logger and see if any Knock was produced. The problem is that I had 87 octane in the car during the tune, so I'm guessing he had some serious knock. It'll have to be re-tuned but I'm waiting for the auto trans shift increase update.

Still I've seen several tuners set these pretty rich, whats up with that?

[abuelo]

11:1 in a N/A motor is EXTREMLY rich. Hemi should go 12 to 12.5:1 Frequently they enrich a little to be on the safe side (richer is safer). And yes, you'll see knocking with 87octane and 91tune; but maybe that's the reason for making it so rich. I dont think you have to wait for the shift increase....you can do that in the quick adjust menu using the tune your tuner did, if they ever get that function back (I REALLY want it too).
Do you know if that fucntion will ever come back?

[PlumCrazyDaytona]

The table was a little off but close enough to dial in with. AFR is set on the rich side in case you the timing is too aggressive for your engine/gasoline you are running. HEMI's do not like lean conditions with detonation, it will cause the top ring land to blow apart, so its best to set rich dial in the timing and slowly pull fuel while watching spark knock and adjusting as needed. A too aggressive tune and bad gas under a lean condition will blow your motor. Lean and mean is not an option with these engines.

Max AFR on a 5.7 12.3, 6.1 12.5 and remember a wideband in car AFR gauge usually has an accuratcy rating of +/- of .1%

[brandy16]

Do you have any 1/4 mile times with the AFR at 12.1.

[PlumCrazyDaytona]

Do you have any 1/4 mile times with the AFR at 12.1.

No track time since 08 when I picked up th Diablo in a group buy of 150....Since then I have a SRT Max cam, ported polished heads, 3000 stall, headers and so forth so yeah the track is needed ASAP!!!

[flo90]

Regarding AFR ratios, How accurate is the "open loop AFR" on the DS Data Viewer? I did a WOT run and it went from a steady 14.71 to a 10.75. I know 10.75 is really rich, but im unsure if theses readings are correct before I go adjusting any fuel. This is with the 93 Oct. CAI Performance tune. I do not have a AFR gauge yet but am looking at getting AEM digital pretty soon.

[mikel]

it is commanded, not actual AFR.