"Cant" run E85 on stock PCM? OK.. why cant we run this? - Page 6 - Tuning Forum

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Re: E85 sucks
Tuesday, April 23, 2013 5:07 PM
oh goodness what have I been missing out on!? e85


still got that 400+whp ecotec running stock pcm and e85. winter, summer, fall, whatever other seasons there are up there in Minnesota, it still runs all year round. No issues.

I'm just glad there is someone else that finally showed up and understands that an o2 sensor doesn't know what fuel is in the system. Don't know do't care. Compensate the injector constant for that necessary fuel demand of e85 and drive away. ** Clearly you will want to monitor and fine tune. But if you tune the car for petrol, compensate for the 30% excess fuel requirement of e85, the car will run, will drive, will get you to work and back. You know what is some craziness, I've been running my car for 1+ years without the oem o2 sensor at all. I unplugged it, put my wideband in the bung and tuned. If my car can run without an o2 sensor at all, I'm quite certain that it can run on e85 too.

I am now currently running a supercharged LE5/L61 with a 2.7 pulley and have yet to put the o2 sensor back in the exhaust. I tune and monitor my wideband and so far no issues. I just moved from MN to MI for my post college job and the car drove the whole way without an o2 sensor and netted 33mpg. The switch to e85 will be coming soon when I pick up some 80# injectors.


Now I am not telling anyone to run their car without an o2 sensor, I just trust my own tuning ability and have my tune set so I can lean cruise on the highway, 15-15.2 afr all the way home. The turbo e85 ecotec does run the oem o2 sensor and it runs fine, you wouldnt know it was on e85 if your nose was stuffed up that day. (e85 smells so good.)







Re: E85 is the bee's knees
Tuesday, April 23, 2013 5:07 PM
/thread






Re: E85 is the bee's knees
Tuesday, April 23, 2013 6:08 PM
I think I said running in open loop (same as running with no 02 sensor), it could be done, just requires more tuning.

It is also more or less a hack way of doing but could be done.





FU Tuning



Re: E85 is the bee's knees
Tuesday, April 23, 2013 7:58 PM
Well it can be done with the o2 sensor as well, and has been done and the car is still running strong. There is a reason they call it an o2 sensor and not a fuel sensor. It doesn't give a damn what fuel you run, it senses oxygen content. If you run stoich on petrol it will return the same value to the computer as if you run stoich on e85, the sensor looks for the oxygen content, not the fuel content. Simple as that. At the end of the day you will just have a higher mass flow rate of e85 into the combustion chamber vs. petrol but the o2 sensor will return the same value to the computer.





Re: E85 is the bee's knees
Wednesday, April 24, 2013 4:25 AM
I find it very very hard to believe that there are "no" issues, especially on cold starts, but I'll have to take your word for it. The fact that you are running open loop and chasing the tune as the weather changes re-enforces the points I was making earlier as well. My previous joking posts aside, E85 is not prevalent where I live, and I couldn't tune someone far away in good consciousness knowing the issues they can/will have.



Re: E85 is the bee's knees
Wednesday, April 24, 2013 5:53 AM
Interesting.... So you are tuning for 9.785:1 now? And manually tuning the PCM to run in closed loop?



Re: E85 is the bee's knees
Saturday, April 27, 2013 7:16 AM
oldskool wrote:

I find it very very hard to believe that there are "no" issues, especially on cold starts, but I'll have to take your word for it. The fact that you are running open loop and chasing the tune as the weather changes re-enforces the points I was making earlier as well. My previous joking posts aside, E85 is not prevalent where I live, and I couldn't tune someone far away in good consciousness knowing the issues they can/will have.



huh? ive never changed my tune. I just watch my afr's. So far I've not had to change my tune even tho ive only ran open loop. Also on his car the tune has never been changed unless he made a physical change to the car i.e. bigger exhaust, different turbo, new intercooler setup.






Re: E85 is the bee's knees
Saturday, April 27, 2013 7:53 AM
Another thing to note, and I think this is what is causing issues for some people, Is that most widebands are calibrated for pump GAS. Therefore when you run a stoich mixture of gas with say an AEM UEGO it will display 14.7. Now most people will assume that just dumping e85 in their car and tuning for it that they need their wideband to display 9.7 for it to be stoich, but the reality of this situation would be a very rich condition. You still need the gauge to display 14.7 because that is what it was calibrated to display when stoich. If you were to have your AEM UEGO set to P0, drive around with gas and it displays 14.7, if you switched to the P1 calibration it would then read lambda 1. If you then tuned your e85 car for lambda 1 (stoich) and switched from the P1 calibration to the P0 one, notice that it will be displaying 14.7 which is still stoich per the "gasoline" calibration. So when tuning e85 you will still look for the same display values, 14.7 stoich, and 11.7ish during boost while tuning. Or if you don't trust that logic, switch to P1 and tune lambda 1 stoich and roughly .8 during boost.
The OEM o2 sensor is the exact same, it has a calibration associated with its voltage output that has been set for the gasoline scale. Nothing on these cars tells the vehicle what fuel is in it, not even that there is gasoline in it, it runs based on a specified fuel flow and pulse width at the injectors with the aid of an o2 to add or subtract fuel based on oxygen content. If you change fuel, e85, meth, whatever, you will need to change the fuel flow and pulse width to provide the necessary fuel and the o2 will still stay there as a backup to add or subtract fuel if it sees the variance from stoich. Honestly the o2 sensor doesn't give a flying @!#$ what fuel you have, give the engine too little and it knows, so it adds more, give it too much and it sees that too, it subtracts. It's not that difficult people. It is also not that precise, its just a narrow band, it shouldn't be anything to rely on. Your tune should be on point where the o2 sensor is never needed or very seldom needed.







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