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Old 09-14-2018, 11:18 AM   #1
vwengineer
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Stock engine, stock map running E85?

Hey guys,

I'm tempted by a small experiment. I would like some advice, in France E85 is lots cheaper than standard unleaded because they give it a huge tax cut (it's about half the price) so a lot of shops there propose so called E85 kits (that increase the injection duration) or E85 remaps.

Lots of people also try to drive with E85 without any modifications as on most cars the ECM will change the fuel trim and automatically increase the quantity of fuel injected so that most cars can drive with no issues with 50% to 100% E85 without any mods (it's not as efficient as with a custom remap especially because you don't change ignition timing to take advantage of the high knock resistance of E85 and the ability to run leaner but still interesting financially).

I would like to try a 50%/50% mix (mostly as an experiment because in Switzerland E85 is not that cheap). I wonder if running a 50%/50% mix could result in the same knock resistance as premium gas?

I am pretty sure that the ECM with it's wide band lambda sensor can make good adjustments in order to avoid running lean, however I am more worried about the fuel line resistance to the ethanol. Especially LPFP, HPFP and injectors gaskets.

Does anybody has experience with E85 or comments?

Thanks
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Old Today, 02:02 PM   #2
vwengineer
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So I did the experience today. Filled around 40% of E85 and the rest with standard unleaded. Car drove well, still had I believe the same amount of power, I still have to check what the knock sensor say, if E85 reduces the knock or not.

VCDS shows an LTFT of 12.9% which is normal I think at this level of E85, I think the car can trim up to 20% before lighting up the check engine light? That would be around 60% of E85.

Will update the post as soon as I do more tests but for the moment it's encouraging.
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Old Today, 03:14 PM   #3
GIACUser
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Quote:
Originally Posted by vwengineer View Post
So I did the experience today. Filled around 40% of E85 and the rest with standard unleaded. Car drove well, still had I believe the same amount of power, I still have to check what the knock sensor say, if E85 reduces the knock or not.

VCDS shows an LTFT of 12.9% which is normal I think at this level of E85, I think the car can trim up to 20% before lighting up the check engine light? That would be around 60% of E85.

Will update the post as soon as I do more tests but for the moment it's encouraging.
As I understand it, parts of our fuel system may not tolerate alky very well. In the building of my motor they did swap out a number of parts to make it e85 compatible. Might be worth investigating.
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