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jasonz28camaro 09-15-2020 01:50 PM

e85 tuning strange things happening
I installed my flex fuel sensor on my swap 68 camaro and I'm having some issues. FYI i have a 6.2/10l80 on a truck OS.

First issue was the alcohol % PID and ethanol % PID initially did not line up correct. Ethanol read correct (50%) and alcohol (10%) never changed. I went through a few ignition cycles and let us run for about 10 minutes total with no changes to the alcohol. I re-flashed the tune and the alcohol % PID read correct after this.

Next issue was me adding full e85 and the alcohol not reading right again. Ethanol went up within 5 minutes to 77% but the alcohol stayed at 50%. Did a few more ignition cycles and let it run for about 10 minutes again with no change. I reflashed the tune and it read correct like before.

This is cause for concern and I'm looking to see if there is a solution out there? The tune is looking for alcohol % not the ethanol % PID and I can see the the commanded EQ going of the alcohol so I need to get this sorted.

Ive been in the process of MAP tuning in open loop and after I got it dialed in going from 50% ethanol to 77% I'm running about 6% lean. Does the tune need some time to get the fueling right after such an increase in ethanol and could the fact that I'm in open loop be hindering the EQ transistion?

thegoat 09-15-2020 02:52 PM

What is alcohol. Is that what the cops install after getting a dui?

Only ethanol pid

jasonz28camaro 09-15-2020 04:58 PM


Originally Posted by thegoat (Post 10868573)
What is alcohol. Is that what the cops install after getting a dui?

Only ethanol pid

Are you a tuner and comedian or just comedian?

I hear you on the ethanol PID but its not the case for me at the moment.

See attached photos.
This determines what AFR you are commanding based off "alcohol" content. This is the main flex fuel table.
This image shows the commanded AFR that reflects the stoich table above and its referencing the alcohol content of 9% not the ethonal PID that shows 44%. If it was referencing the ethanol content of 44% the AFR would be commanding around 12.1, not the 14.1 that reflects the 9% alcohol.

thegoat 09-15-2020 06:00 PM

Do you have flex fuel set to sensor or virtual?

jasonz28camaro 09-15-2020 06:50 PM


KingLT1 09-15-2020 06:56 PM

You only use the Alcohol PID to monitor Ethanol content. The fact that your only seeing 9-10% tells me the ECU is not seeing the sensor. Check your connections.

jasonz28camaro 09-15-2020 07:27 PM

It sees it after the reflash and the alcohol matches the ethano, the alcohol and ethanol both matched after the reflash. Then today I added more e85 and my blend measured 77% ethanol but the alcohol did not pick it up and stayed at previous blend percentage until I reflashed it. Now both measure 77%. Something is happening and I don’t want me fueling to be crazy when I change the blend up each time.

All connections have been checked and double checked at each pin including the ECM pin.

6spdhyperblue 09-15-2020 07:28 PM

How long do you drive it after you fill up and it mismatches? Before reflashing it

jasonz28camaro 09-15-2020 07:38 PM

Not long that’s one of the questions I had asked. Roughly 10 minutes. My only concern about that is that the ethanol PID reads correct within 2 minutes but not the alcohol PID and fuel trims are off by 12%. They both pull the data from the sensor so it’s just strange. If this is normal and I need more drive time then I’m good with it.

6spdhyperblue 09-15-2020 07:46 PM

It could take 15-20min. What volumes do you have in the fields like liters before it levels out etc, and what’s the distance between the ff sensor and the injectors

jasonz28camaro 09-15-2020 08:01 PM

I’ll need to check but it hasn’t been altered. I think it’s like .25L or something

6spdhyperblue 09-15-2020 08:05 PM

Is the sensor near the engine or back by the tank

jasonz28camaro 09-15-2020 08:07 PM

Yea it’s .28L.

So this makes a little more since. This learning trigger says it is the volume required before the new composition reaches the engine. This I guess could apply to the alcohol pid and the ethanol pid could be more of an immediate number. .28L is a very small amount, maybe a mile worth of fuel or so? I’m pretty sure I either did not use that much or was very close to hitting it.

jasonz28camaro 09-15-2020 08:08 PM


Originally Posted by 6spdhyperblue (Post 10868758)
Is the sensor near the engine or back by the tank

3 from the engine

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