AFR What you should know.... LONG

wayne, thanks for posting the write ups, i will be reading as more come!

i have a question. where i live they say the gas contains up to 10% ethanol. so does that mean my gas has E10 in it??

i found this on the sunoco web site:

"In compliance with federal law and as stipulated by most automobile manufacturers, Sunoco gasolines contain no more than 10% ethanol."

i have never used race fuel or any higher ethanol fuel, but it appears i should be aware if i do.
how can we measure for this and change our readings so we are reading the correct and "true" A/F??

Sean
 
lightning25 said:
wayne, thanks for posting the write ups, i will be reading as more come!

i have a question. where i live they say the gas contains up to 10% ethanol. so does that mean my gas has E10 in it??

i found this on the sunoco web site:

"In compliance with federal law and as stipulated by most automobile manufacturers, Sunoco gasolines contain no more than 10% ethanol."

i have never used race fuel or any higher ethanol fuel, but it appears i should be aware if i do.
how can we measure for this and change our readings so we are reading the correct and "true" A/F??

Sean
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Sean, i am not expert nor did i write this but have been studying and speaking with the person that did write it. When you see contains no more than 10% ethanol on the pumps that IS E10 fuel!

The way i see it is that if you are tuned for lets say a 11.6 A/F @ WOT on straight gas and then run E10 you want to be tuned for an 11.04 A/F @ WOT to make up for the difference in stoich.

Wayne
 
Does the WB show leaner if you switch to E10? Or does it show the same A/F reading but the truck is actually running leaner????


Thanks,

Ray
 
Humm... 11.264 is safe for E10 (AKA 93+10% Ethanol)
Well I asked JDM yesterday if they took into account for E10 in their tunes and they said that yes... they did. I'm currently on my break-in tune and haven't gotten into the boost at all yet, but when I get onto the throttle a bit on the HW to pass, I'll let my boost go all the way to 0 and my AEM Wideband will read as low as 10.8 right before it shifts. So that would be a tidge lean... correct? So I think it would be safe to say that if/when I get into the boost that it will be really lean. I'm just guessing here, because I haven't done it yet. But the truck idles @ around 15-16... which is really rich.
 
autenb said:
Humm... 11.264 is safe for E10 (AKA 93+10% Ethanol)
Well I asked JDM yesterday if they took into account for E10 in their tunes and they said that yes... they did. I'm currently on my break-in tune and haven't gotten into the boost at all yet, but when I get onto the throttle a bit on the HW to pass, I'll let my boost go all the way to 0 and my AEM Wideband will read as low as 10.8 right before it shifts. So that would be a tidge lean... correct? So I think it would be safe to say that if/when I get into the boost that it will be really lean. I'm just guessing here, because I haven't done it yet. But the truck idles @ around 15-16... which is really rich.
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Your assumptions are backwards...
 
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Sal is correct the high number lean, lower number rich. Meaning a 10.80 is richer than a 14.4

And it sounds like you have a nice safe tune! With those A/F numbers.

Wayne
 
So... since it's 15.5 while cruising... and as high as 16 and my meter even reads -- when i'm @ idle sometimes... That's lean, but it's ok, since there's no load on it?
But... 10 and 11 is GOOD when i'm giving it throttle... but 13 or 14 while i'm giving it throttle is NOT good? (sorry... i'm trying to grasp a concept here.)
 
autenb said:
So... since it's 15.5 while cruising... and as high as 16 and my meter even reads -- when i'm @ idle sometimes... That's lean, but it's ok, since there's no load on it?
But... 10 and 11 is GOOD when i'm giving it throttle... but 13 or 14 while i'm giving it throttle is NOT good? (sorry... i'm trying to grasp a concept here.)
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Correct!

Wayne
 
so here's the back breaker... how lean does it have to be before it causes detonation? I mean... since it runs @ 14.7-15.5 while @ 2Krmp @ 65mph... does that mean that it is very likely detonating?
 
I cant answer that question. Detonation has alot of factors. IAT2 Temp, Load, Timing, Fuel, Air/Fuel, compression ratio, etc...

Wayne
 
autenb said:
so here's the back breaker... how lean does it have to be before it causes detonation? I mean... since it runs @ 14.7-15.5 while @ 2Krmp @ 65mph... does that mean that it is very likely detonating?
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No, you should see 14.7-15.5 at that speed. Its when you roll into WOT you should see your wideband drop to 11.xxx.

Rich
 
Good. VERY good. I'll have to do some datalogging once I have my street tune installed here in a few hundred miles.
 
rtkjadams said:
I think I understand alittle.... Using the info from above, if I'm running 93 my A/F will be 11.712:1, but if filled up with E10 then I need to tune to get my A/F to show 11.264:1 (14.08 * .80) to be safe?????


Ray
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INCORRECT. No matter the fuel, your AFR wideband will read the same as it does with any other fuel if you do not reprogram the wideband to use a different stoich value for the different fuel. It does NOT care what fuel is in the vehicle it only reads the amount of oxygen is in the exhaust. It will take more fuel with alcohol based fuels than on petroleum based fuels to achieve the same reading on a wideband programmed for gasoline. I am on full E85 and my wideband has the same conversion from lambda to gasoline that most widebands come with from the factory--it is just a normal AEM wideband. So, when I tune, I want to see somewhere between 12.8 to 13.2 AFR or something similar to what a race fuel tune would have. The amount of fuel I am commanding is much greater than gasoline, but the wideband should read the same.

As for the tune:
When you have you tune to run an 11.712 on non-ethanol fuels and put in E10 your wideband will read a little leaner. Somewhere around 12 to 1 (depends on the actual blend of ethanol to gasoline in the E10--the reason why the signs say up to 10%). If you plan on using only ethanol blended fuels, then tune your wideband to read the same AFR as you would use for straight gasoline; i.e. 11.712 AFR reading on your wideband. It will take a couple % more fuel to achieve the same reading on your wideband.
To explain using your example above, you have a gasoline tune with an AFR of 11.712 at WOT. Now you retune to the ethanol blend fuel to achieve an AFR of 11.264. Now instead of adding 4% more fuel to maintain your AFR of 11.712, you added 8% more fuel and essentially richened up the tune and killed a little power.
 
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I did notice that my WB is reading alittle leaner then it use to before the E10 fuels..... It is actually reading 12.0 - 12.1 WOT now..... So would I be fine if I got it back to the 11.7 ???

Ray
 
Ethanol is a great octane booster. Are you running the 93 octane E10? If so and if you are not detonating and the plugs are coming out great, then you should be OK.
 
91 Probe GT said:
do you know what the numbers are for unleaded 91 octane e10? That's the best i can get where i live.
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If it says 91 octane and up to 10% ethanol, then it is probably much less than 10% ethanol. Most of the real E10 that I have used actually says "E10" at the pump with a stated octane of 93. I would just tune for 91 octane to be safe.
Here in Oklahoma, we have ethanol blended fuels with up to 10% ethanol but only 91 octane, however, it is not the best fuel nor is the non-ethanol fuels we have around here. That is why I run E85 and just take the hit on fuel economy.
 
What all would a guy have to do to convert and run e85? anything special a guy needs or is it just a matter of pumping more fuel in to compensate for the extra ethonal? Our pumps claim 91 octane with the e10. I have a predator tuner, and my maf extender is only on number 2 right now. I think I have 50lb injectors running a 2.3l kb. Can a guy make more power with a good tune on e 85? I would assume so beings it has a higher octane rating.
 
Great discussion! I do have a couple things to add that may make everyone's life a little easier.

It's really, really wise to get a wideband that also reads Lambda. That way you don't ever have to worry about doing some kind of conversion. Because no matter what fuel you are running, the stoich point will always be Lambda 1.0 - and you'll always know that your target lambda will be right. For instance if you are targeting an 11.5 A/F ratio and you want the equivalent A/F ratio with an alcohol fuel, all you do is log Lambda on the meter and look for around 0.79 Lambda and all will be good. As mentioned the 02 sensor doesn't 'care' about A/F ratio - putting it simply it's 'native' language is lambda. The A/F readings you see are based on internal calculations done within the wideband which you a reading for gasoline.

The other thing to consider is, as mentioned, E85, ain't always E85 - in fact here in Ohio, it varies by season, so you may get E60, E70 or maybe E92 sometimes. You never know. And virtually ALL gas nowadays is at least E10, sometimes it's posted on the pump, sometimes it's not.

To be really sure, and on a vehicle tuned on the edge, I always use Zeitronix's new nifty tool - an Ethanol content analyzer - you have to also buy a flex fuel sensor, but it works really well and is a must here up north.

Hope this helps,

Don LaSota
 
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