The wide band from Dodge shows a value of 13.5 on the gauge. When idling it swings from 13.4 to 13.7 with most of the time sitting at 13.5 to 13.6. I would think Dodge knew what they were doing when designing these wide bands. I have a feeling they are accurate and the true stoic is around 13.6. Not 13.85.
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
stoich is dictated by the fuel in your tank, not a tune and not a wideband and not a dash gauge.
You need to look at this from a Lambda perspective. Stoich is based on a Lambda of 1.00. Typical Stoich AFR (14.7) is just simply Lambda 1.00. What you are seeing is just an afr reading calculated by the computer using .072 FA ratio as the Stoich value, or 1.00 Lambda. So if you want to see what AFR take 1/.072 which equals 13.88 which is what the computer calculates as stoich AFR. Keep in mind this still is a value of 1 lambda, so if this is measured using a standard wide and gauge setup for gasoline AFR it is going to read approximately 14.7.
Originally Posted by mxatunerjg
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
Are you getting the .072 by looking some where at the stock tune on hp tuners? I switched to diablo. On my wide band it reads 13.5 and that is where Dodge has the middle point of the wide band on the heads up display.
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
OK, I read a stock tune and I see where you are getting the .072. But I wonder why my Hell Cat reads 13.5 instead of close to 13.9 at idle. Does it just idle richer than stoic?
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
It may just idle a bit richer. I've seen them range from 13.4 - 13.9. A lot of other factors come into play here too. The computer is going to be calculating for many atmoshperic conditions as well, and all of those things with have an effect on this. The main thing you want to worry about isn't so much what it is reading, but what the trims look like. If the trims are in line (assuming you don't have a bad oxygen sensor) then the computer is happy and the exact number it is reading on the dash is not really what you should be worried about.
It is interesting what a member pointed out on the hellcat forum. It is strange how you can be looking straight at something and not see it. Right in the middle of the dash where you bring up the afr is the lambda sign. Then right by the 13.5 numbers where it idles at there is the words stoic pointing right at the 13.5. I am wondering in the formula that hp tuners is using if something else plays into the straight math of 13.88. It is hard for me to fathom that Dodge does not know its own stoic especially with the lambda sign and stoic pointing right at the 13.5.
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
This.
I don't understand why people, especially professional tuners still even speak in AFR especially with all the different fuel types we run in to.
When I was at the Holley EFI dealer tuning class earlier this year. Tom our instructor I think nailed it when he said, "Lambda is the metric system and everyone in the US refuses to use it."
Hellcats have a bias in the stock wideband as well, if you read with any other aftermarket WB the readings will be different.
because the Hellcat's stoich isn't 14.7 like any other aftermarket WB.
So Jay I am a bit confused. Let's say Dodge is correct with their lambda and stoic of 13.5. If I put E10 in my Hell Cat which has a stoic of 14.08 and my on board wide band reads 11.8 from Dodge am I running at 11.8? Or am I approximately running at 14.08/13.5 x 11.8?
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
lambda.jpg
Cactus,
A WB sensor is a Lambda sensor, it doesn't care what fuel is being used. It's looking at oxygen only. AFR is derived from the atomic weight of a particular fuel type and oxygen. Then the oxygen fuel mass ratio is determined. Air is only about 23% oxygen. So after some more math stoich is determined for that particular fuel type.
On wideband that is setup for E0 gasoline stoich is 14.7. You can put E10 in the tank and it will show 14.7. You can put E85 in the tank and it will show 14.7. Why? Because the WB is only looking at oxygen. It displays AFR because that's what people want to see.
To answer your question if you are running a different fuel type than what the stoich is programmed for then no you are actually at a different AFR than what's being displayed. That's why Lambda is so much easier.
The screen shot I attached shows the different fuel types and their AFR in relation to Lambda. AFR confuses the shit out of me when I change fuel types, that's why I don't use it. The WB starts with Lambda and the AFR is just math to display a certain number.
I hope some of this makes sense because I confuse the hell out of myself every time I try to explain it.
Last edited by Jay@HAP; 07-30-2017 at 06:00 PM.
Maybe Dodge is trying to tell us to use lambda too.Look in the center of the gauge
2016 Hellcat - 800 Miles - It's winter
Also, log your wideband sensors. I bet if your seeing 11.8 on your dash, your widebands are reporting 12.5 AFR in the scanner.
2016 Hellcat - 800 Miles - It's winter
That is exactly what I was saying. That on my dash it reports what you are showing. And the 11.8 is really much higher. 11.8 x 14.10/13.5.
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
I understand what your trying to say.
It could be that Dodge uses Fuel/Air not Air/Fuel for fueling calculations.
This is why I took Jay's advice and tune with Lambda, it's easier.
The dash reading is for entertainment, my opinion anyway. It appears to have a 6% bias. 13.85 reported by dash, actual AFR 14.68
2016 Hellcat - 800 Miles - It's winter
So most if not all aftermarket wide bands read lambda and have built in calculations for what fuel you select. Most go to the dark side and choose raw lambda. its like the metric system universal for all fuels. straight gas scale is like the imperial it works but you have to do some math to scale it out to other fuels. The hellcat has an offset table that really messes up the stoich settings and wideband display. Like set it to .68... whatever and wot lines up but idle is richer and never goes back to 1.0 in the closed loop logs when demanding 1.0. Plus its all kinds of lean in all kinds of places. It never would lean out at idle so I never continued.
This. You guys gotta start thinking in terms of lambda. You're causing all kinds of uneeded confusion using afr.
So on a HellCat what lambda produces the most power? After doing a lot of reading I realize each vehicle is different. But .83 seems to be a good solid number?
2016 Hellcat Challenger, automatic, black on black with brass monkey wheels
10.13@ 140 DA 5000 feet
2.75 pulley, tune, drag radials. 10 percent lower od crank pulley, 1050 ix. off road mid pipe. tune
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