Flex Fuel Conversion for more power problem

[Bill Marshalonis]

Any ideas on how to check the flex fuel sensor's output to the ECM?
I changed to a smaller pulley on the supercharger and now it gets 15 lbs of boost. However, I was running out of gas at 5500 rpm. The injectors were running at 100% and the fuel pump was not keeping up.
I changed the fuel pump to an aeromotive A750 and 60 lb/hr injectors.
Now I have enough fuel, but not enough octane to prevent pinging. I had to retard the timing.
I have installed a Flex Fuel sensor from Continental and have the correct connections to the ECM (Pin 56 blue) and put 10 gallons of E-85 in the tank to see if that would increase the octane.
The problem now is that HPTuners shows 0% ethanol. I cannot tune it for E-85 if it shows 0%.
I am going to check the Flex Fuel sensor's output, but my meter may not measure pulse modulated DC to the ECM. Any ideas on how to check the flex fuels output to the ECM?

 

[swathdiver]

It should be available in the Fuel Trims section. What kind of interface are you using to see what the computer is seeing?

 

[randeez]

I'm guessing this isnt a 2015+ truck?

 

[Bill Marshalonis]

It is a 2003 Tahoe Z71, and I am working with a tuner that uses HP Tuner software on a chassis dyno.
You can check out the Tahoe at my webpage at www.steelwebworks.com/BigRed/index.html

 

[randeez]

I dont know the answer for ya but, those years didnt use a continental sensor oem, i would start by finding some info on the oem sensor and see if it used the same output

 

[Bill Marshalonis]

The Tahoe did not come with Flex Fuel at all. It is a mod that I put together to boost the octane. There is a port and pin position on the ECM for a Flex Fuel input, but the engine did not come as a Flex Fuel engine.
The Continental sensor has 3 pins - 12vdc and ground in and % ethanol out to the ECM. Did a resistance test to the ECM, and verified the 12vdc and ground.

 

[swathdiver]

The Tahoe did not come with Flex Fuel at all. It is a mod that I put together to boost the octane. There is a port and pin position on the ECM for a Flex Fuel input, but the engine did not come as a Flex Fuel engine.
The Continental sensor has 3 pins - 12vdc and ground in and % ethanol out to the ECM. Did a resistance test to the ECM, and verified the 12vdc and ground.

I think this question will be answered faster if posed to the Performance Trucks forum. I do not know if the LM7s used the same tables as the L59s sans sensor but those guys over there might.