View Single Post
Old 08-14-2009, 01:06 AM   #40 (permalink)
2000mc
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,049

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.74 mpg (US)
Thanks: 43
Thanked 331 Times in 233 Posts
nope, didnt, looked like re hashed version of

http://www.ethanol.org/pdf/contentmg...yStudy_001.pdf

back when it didnt work for em at all except with some wierd denatured alky/biodiesel stuff i've never heard of....
...but now i see they have

http://www.ethanol.org/pdf/contentmg...inal_12507.pdf

now they think they have something but they dont... they forgot to bring a gm tech to thier tests...

theyre excited about a chevy that cant handle the test because they dont use actual fuel sensors anymore, and only recalibrates to adding e0-e10 or e85, it cant handle adding mixtures in between, you can drive on e10, add some e85, and have a tank of e30 just fine.... but dump in e30, what will happen isa crapshoot.


from gm SI fora 07 impala
E85 Flex Fuel Description

E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.

The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.

Air-fuel ratios and the corresponding ethanol percentage are updated following each purge-off sequence. the fuel alcohol content percentage value can be read on a scan tool.

When an E85 compatible vehicle is built, an ECM replaced, or if the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10% or less ethanol content.

A minimum of 11 Liters (3 gallons) must be put in the tank in order for the vehicle to recognize a re-fueling event. It is not necessary to turn the ignition off in order to have the re-fueling event recognized; however local safety regulations should be followed.

After the re-fueling event, the system registers the amount of fuel that was added, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines if the fuel added was either ASTM Gasoline or ASTM E85. Based on that determination, the system adjusts to the expected alcohol mix in the fuel tank, and then the fuel trim and O2 sensor activity fine tunes the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or E85 to gasoline, can result in driveability symptoms due to the inability of the system to adjust for fuel composition by not attaining closed loop operation.
  Reply With Quote