ecartoys:
Quote from: redevo7 on January 15, 2009, 01:06:16 AM
You can run the AEM AFR Gauge with any Fuel ( except Leaded ).
The sensor is reading LAMBDA, not AFR, at any time.
So there is no need to read lower than 10.0 AFR.
The Gauge will transfer that LAMBDA to an AFR onto the display for selected Fuels ( Gasoline, Methanol...)
BUT: Stoich Mode is 14.7 equals Lambda 1 for Gasoline.
If you running E85, it will read also 14.7 equal Lambda 1. ( but you need app. 33% more fuel for Stoich )
So, leave the Gauge in Gasoline mode, you can tune with E85 like you do it with Gasoline. Choose the same AFR you will use for Gasoline. then try to map it as you want, you will feel what the engine needs. Sometimes its getting more power by leaning E85 a bit out, sometimes the engine likes it to run a bit richer than on gas. All depends on compression Ratio, Timing, Head shape,....
A little confused still. If I switched the gauge to show lambda instead of the AFR do I need to calibrate for 33% more fuel or can I just go by lambda value for E85 which is 0.714 for power rich and 0.867 for power lean?
Thanks.
TurbodGSR96:
You dont change anything, just pretend you still have Gasoline in the car and tune to Gasoline AFR's, the UEGO is looking for lambda and will convert its readings to display normal AFR's automatically. I run E85 in my Turbo Integra and its tuned to 11.7 AT WOT just like I was running Gasoline.
It took me a while to understand this as well, trust me I am correct.
pdeod:
Yes, Hes Correct about thr readout, it will convert. but the car has to be pretty much on wide open throttle. Carb adjustments( HOLLEY TYPE ) to the idle mixture screws must be made for whatever( leaner or ritcher) take the car out and monitor the gauge readout and readjust as nessessary.
Jim
ecartoys:
Thanks guys. :-D
A few more questions to the E85 gurus. According to the info I found, Rich Power AFR is 6.975 and Lean Power is 8.47 while Stoich is 9.765. If I am tuning to Gasoline AFR do I use the numbers above or use TurbodGSR96's AFR number of 11.7 which to mean is very lean on the E85 scale.
I am running a turbocharged 3.5L Inline Six with Motronic Injection - 1985 BMW 745i. I just want to make sure because I do not want to be leaning the engine out on boost. I understand that stoich is 1 Lambda for both Gasoline and E85 which the UEGO is translating to 14.7 for gasoline. Question is how does the translation go with the E85? Do I need to do the math separately to get the correct numbers for E85 or is there another way?
Thanks.
NS:
What TurbodGSR96 is trying to say is that acceptable gasoline AFRs basically translate to acceptable ethanol AFRs. We know that stoich for any fuel is Lambda 1. An acceptable high load AFR for gas is 12.0:1 which also happens to be .82 Lambda. Now, .82 Lambda for ethanol is an AFR of 8.00:1. If a gas AFR of 12.0:1 = .82 Lambda and an ethanol AFR of 8.00:1 = .82 Lambda that means that a gas AFR of 12.0:1 is the same as an ethanol AFR of 8.00:1.
If I were in this situation I'd just set my UEGO to read Lambda and know that anything less than about .87 Lambda is safe in high load. Or you can condition yourself to remember that the indicated gas AFRs on your UEGO are comparable to ethanol AFRs by ratio and not the actual number shown if that makes any sense.
