Virtual Flex Fuel and Headers E38

[jaker]

I apologize if this has been previously covered, I did search for awhile. I have an 08 Suburban with flex fuel e38pcm and would like to do some long tube headers. Obviously the virtual sensor works with the gas gauge and 02 sensors among other things to find the percentage of ethanol. Knowing transient times for the o2's and even trying to keep them warm can sometimes be an issue with long tubes.

Would running long tubes be a huge hurdle with virtual flex fuel? Would it be easiest to just run a flex sensor? What are my options?

Thanks in advance!

[5FDP]

Virtual sensor is useless to me, it can't be very accurate because it's not a real sensor. I just disable it because they can read wrong all the time. You'd be better off installing a real flex fuel sensor if you want to run E85 fuels.

[jaker]

Being in WI I'd love to keep running E85 in the summer like I have in the past. It's been working OK so far but I did have some issues with it a few months back. LTFT's were +25 with e85 in the tank. Should of been around e60 at the time, some reason it f'ed that up.

I did do some research with the flex sensor. Seems like it's a decent install, but I'm totally blind on the tuning aspect. How would you disable the virtual and enable the sensor? If anyone can lead me to a write up that'd be awesome.

[schpenxel]

I've seen a few people around here chasing their tail by having the virtual sensor turned on.. At the very least I would disable it while tuning and set the whole stoich table to match the actual stoich for the ethanol content you're running.

Or you could add a physical sensor.. it's not bad at all to install

There should be a drop down box to change virtual to physical or something like that

[jaker]

Been doing some research again on adding the sensor.

This I thought was fairly informative even though it doesn't relate with trucks or my ecu.
http://www.sonicownersforum.com/foru...formation.html

This was also a nice write-up using the e38 pcm that you schpenxel, posted a week ago
http://www.grrrr8.net/showthread.php...l=1#post524941

Still trying to figure out exactly what needs to be changed in hpt. I do see the drop down for virtual to sensor, that's easy. Is there anything else that I need to know for the tune once I add the sensor?

[schpenxel]

It depends on current tune but if it's already setup for "virtual" flex fuel sensor then it will likely just be switching it from virtual to sensor to get it working. You can log ethanol sensor frequency or something like that to see if it's working. 50hz = 0% ethanol, 150hz = 100% ethanol and everything inbetween is pretty self explanatory

It's pretty much stoich AFR table, flex fuel spark, flex fuel spark comp multiplier and PE (alcohol) are the main ones that I can think of

[jaker]

Awesome, you've been a huge help! Thanks