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Adding flex fuel sensor to my e85 04 GTO?

27K views 63 replies 21 participants last post by  Nothubertjfarnsworth 
#1 ·
Alright, so either I suck as using the search function or there isn't any solid info on this topic.

I have an 04 GTO that I already have set up and running on e85. Been running great for over a year, but I have it running full time with no flex sensor. I'm getting tired of the occasional fluctuation of ethanol content in e85 in my area, and having to adjust the tune to compensate. I know I will need to pin in and plumb a flex fuel sensor. What's all needed on the tuning side? Segment swap? Different OS? I have HPtuners and am fairly fluent in it, and do all of my own tuning. So what's needed to be done on the software side of things?

Thanks
 
#3 · (Edited)
#5 ·
It's not plug and play, tune still needs to be adjusted
 
#11 ·
SNS stage 2 cam, ported 241s, long tubes, 3800 stall 4l80e, 100-150 shot depending on the day, and full bolt ons except for intake. No idea on numbers or ET gain, since I went to the 4l80e, changed the cam, and e85 at the same time after wrecking the old cam.

Fuel system is stock aside from TRE 42lb injectors and quantum 320lph pump.

Main differences I feel are a wayyy smoother idle and its a lot more forgiving if it goes lean (OLSD). Accidentally set a few cells so lean at one point that it pegged my wideband. Barely felt a difference in driveability while on gas, it wouldn't even try to run.
 
#7 ·
Os needs to be swapped. Gto os is missing some background stuff to work with the Sensor. Sensor needs to be pinned in. I ran into fuel gauge issues when I did it. Had to try a couple different segments with the new os to get the gauge to read. I could log the fuel level sender with the scan tool but the instrument cluster would say fuel gauge error.
 
#12 ·
So is yours reliably running with flexfuel enabled now or are you still working out bugs? I haven't had time to do anymore research on the topic since I first posted.
 
#8 ·
Interesting. Please go on.

LR
 
#9 · (Edited)
dreadpirateroberts

You subbed for info and your profile indicates that you have an '05. It was for YOUR benefit.
 
#19 ·
Eaglegoat who posted somewhere above should be able to point ya in the right direction. It will take an OS change, and an added wire but it's otherwise pretty straight forward. Spoke to dedicated motorsports they hooked me up with a sensor and a pigtail harness, I'll be doing the rest. Will be doing the install over the winter so I'll have some feedback in the spring
 
#23 ·
Looking at the pin outs for the 2004 gto and a 2004 flex fuel 5.3 the trucks used pin 56 on blue connector and 04s ate unused there. The rest of the wires on the blue connector for each vehicle are nearly identical. Anyone with the sensor care to confirm which pin you used on the pcm?
 
#31 ·
I recently found a station with e85 less than 20 miles from my house. I guess now I have an excuse to look into bigger injectors for my new turbo build, as 60's won't be nearly enough anymore. I previously had no reason to even consider e85, as it just wasn't available.
 
#32 ·
Doesn't look like it is possible to have the PCM control the reverse lockout solenoid using the truck OS. They did not have this function and isn't anywhere to be moved or turned on the truck OS.

Pin 44 on the green connector is the ground from the pcm to engage the solenoid. Looks like you will have to run your own switch to use reverse. Yellow wire c2/44 is the ground from the pcm for under 3mph or w/e. I'm going to run a switch to break ground for now.

If you look threw the 04-07 blue green p59 truck pinouts there is no reverse lock out solenoid.

Maybe a trans segment swap would work.
 
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