$289 Flex Fuel conversion kit for fuel management

nutty1 · 03-26-2008, 05:08 PM

With high gas prices i've been reading up on the e85 Flex fuel kits.

based on the fuel mixture being in thte tank, it senses the factory O2 sensor , and shorten or lengthen the injector pulses too lean out or add more fuel to correct the AFR.

I wonder if this can this be used to the manage the fuel of our modified engines .

If this works, it would be very simple plug and play kit for AFR. Horsepower freaks has something similiar but little more complex for around $500 bucks.

Anyone try this yet? dynoed?

karl · 06-13-2008, 12:29 AM

factory O2 sensor can only tell it if it's rich or lean, not HOW rich or HOW lean. meaning it would have to add in small increments to get the mixture right. that's fine for cruising, but you don't want it doing that when the ECU is in open loop under boost. granted, E85 can run pretty freekin lean under boost (i've seen 13:1 gas equiv and no signs of det on my car), but something that works the way you're describing would be too slow in real-time.

there are other kits that basically just take an injector pulse and add ~25% to it to make it run E85, but MR2s can run as high as 100% duty cycle, and you can't add duty cycle to 100%. add to that the fact that each injector is basically running 1 cycle behind where the ECU thinks it is.

neither is a good strategy. if you want to have flex-fuel capability on the stock ECU, your best bet is a fuel pump, an AFPR and a wideband.

Enthalpy · 06-13-2008, 03:32 PM

I have done quite a bit with E85. It's not really a substantial cost benefit, but you do get higher octane fuel for the overall price of pump gas.

It's very corrosive. Even some factory flex fuel vehicles have issues with this!

As for adding it to our systems, that's rolling the dice. It can fail in ways you might not realize until something catches fire. I personally wouldn't do anything but redesign the system and EMS it. I cringe when people half-ass fuel systems.

rousegk7 · 06-13-2008, 04:18 PM

03-26-2008, 05:08 PM	#1 (permalink)
nutty1 trading luck for skills Join Date: Sep 2007 Location: houston, tx Posts: 136 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	$289 Flex Fuel conversion kit for fuel management With high gas prices i've been reading up on the e85 Flex fuel kits. based on the fuel mixture being in thte tank, it senses the factory O2 sensor , and shorten or lengthen the injector pulses too lean out or add more fuel to correct the AFR. I wonder if this can this be used to the manage the fuel of our modified engines . If this works, it would be very simple plug and play kit for AFR. Horsepower freaks has something similiar but little more complex for around $500 bucks. Anyone try this yet? dynoed?

06-13-2008, 04:18 PM	#4 (permalink)
rousegk7 Cage Fighter Join Date: Mar 2007 Posts: 322 Thanks: 15 Thanked 9 Times in 9 Posts iTrader Rating: (5/100% )	^ +1

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06-13-2008, 12:29 AM	#2 (permalink)
karl all macgyver on it Join Date: May 2006 Location: robbinsdale, MN Posts: 296 Thanks: 1 Thanked 30 Times in 23 Posts iTrader Rating: (0/0% )	factory O2 sensor can only tell it if it's rich or lean, not HOW rich or HOW lean. meaning it would have to add in small increments to get the mixture right. that's fine for cruising, but you don't want it doing that when the ECU is in open loop under boost. granted, E85 can run pretty freekin lean under boost (i've seen 13:1 gas equiv and no signs of det on my car), but something that works the way you're describing would be too slow in real-time. there are other kits that basically just take an injector pulse and add ~25% to it to make it run E85, but MR2s can run as high as 100% duty cycle, and you can't add duty cycle to 100%. add to that the fact that each injector is basically running 1 cycle behind where the ECU thinks it is. neither is a good strategy. if you want to have flex-fuel capability on the stock ECU, your best bet is a fuel pump, an AFPR and a wideband.

06-13-2008, 03:32 PM	#3 (permalink)
Enthalpy EMS Harmonizer Join Date: Feb 2006 Location: Denver, CO Posts: 1,219 Thanks: 8 Thanked 54 Times in 42 Posts My Google Map iTrader Rating: (2/100% )	I have done quite a bit with E85. It's not really a substantial cost benefit, but you do get higher octane fuel for the overall price of pump gas. It's very corrosive. Even some factory flex fuel vehicles have issues with this! As for adding it to our systems, that's rolling the dice. It can fail in ways you might not realize until something catches fire. I personally wouldn't do anything but redesign the system and EMS it. I cringe when people half-ass fuel systems.