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

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.

vwengineer said:

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.

Click to expand...

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.

Thanks for the feedback, I appreciate it. Do you know which parts in particular? I did not find that many informations only a marketing sheet saying that the HPFP is resistant to ethanol. I know they tune similar cars with ethanol maps and that they need to upgrade the HPFP to do an "E85" stage 1 due to the additional fueling required but I am not sure if they do other changes.

Usually a car the is designed to run E85 has special rubber hoses and lines that do not breakdown because of the alcohol. Not sure if it is a major issue, I ran e85 mix in my BMW for years and it was not rated for it and I never saw a problem.

I guess over time though the rubber can fall apart and so you could have tiny particles clogging injectors etc.

I've read that any rubber gaskets or hoses exposed to fuel that arn't neoprene rubber are subject to alcohol rot. Aren't you concerned about the higher temperature in the combustion chamber that alcohol produces? I've heard it can cook your valves over time if they are not made to handle that heat. I'll throw in the catalytic converter too while I'm ranting.

Thanks for your inputs. I am not sure about the lines but in some European countries (France, Germany) now the standard unleaded is in fact mixed with 10% ethanol and apparently most cars since 2000 are compatible. I would think that compatible cars have lines that are resistant to ethanol but I am not 100% sure.

Regarding heat you are correct if we speak about an E85 specific tune because you can run E85 very lean as it is knock resistant, so that the temperature gets higher and cooks the valves. However this is not the case with the stock map because it injects actually 13% more gasoline which leads to lower temperatures than with straight gasoline to my understanding.

Did you look in your owners manual about blended gas. They list E10 as the maximum.

No disrespect intended...I'm sorry, risk/reward from this exercise just isn't worth it. I know it can be hard, but let the temptation pass my friend. Pick another project....

GTI's said:

Did you look in your owners manual about blended gas. They list E10 as the maximum.

Click to expand...

I didn't but I understand that as a liability/software limitations because the engine management has no ethanol sensor and no E85 map its adaptation ability is limited. It's more like a hack because you rely on the O2 sensor and fuel trims to get it running right which is not 100% optimal but works (I get an LTFT of 13% with 40% E85, while with 100% E85 you need to trim by 25-30% so it's almost spot on).

Another advantage assuming the gasket and fuel lines hold is that E85 is pretty good at cleaning everything like injectors, combustion chamber, etc...

As I said this is a limited experiment as E85 is expensive in Switzerland so economically it makes no sense so I will not run it that often, in France that would be a saving of about 12$ per tank taking everything into account.

So I did a pull in third today with logs, it might be a bit difficult to read but I am quite happy with the results, car pulls really well, it runs actually a tad richer than specified under high load which is good for the engine and most importantly, there are no ignition timing corrections due to knock.

So using standard unleaded + E85 = premium gas. This is actually great because I have the AXX engine which has higher compression than BPY or BWA so it is highly sensitive to the octane level (VW advises to use only premium fuel but it can run on standard if needed). With standard unleaded it corrects up to 6.

Engine Speed Engine Load Boost Pressure Boost Pressure Timing Retardation Timing Retardation Timing Retardation Timing Retardation Lambda Control Lambda Control

TIME (G28) (specified) (actual) Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Bank 1 (actual) Bank 1 (specified)

Marker STAMP /min % mbar mbar ｰKW ｰKW ｰKW ｰKW

74.5 2080 20.3 350 970 0 0 0 0 0.98 1
74.89 2080 19.5 360 970 0 0 0 0 1 1
75.26 2080 21.1 380 970 0 0 0 0 1 1
75.66 2120 36.1 1230 950 0 0 0 0 1.02 1
76.05 2200 82 1850 1030 0 0 0 0 0.97 1
76.43 2320 95.5 1850 1290 0 0 0 0 0.99 0.96
76.81 2520 115.8 1820 1570 0 0 0 0 0.97 0.95
77.2 2680 130.8 1810 1820 0 0 0 0 0.95 0.95
77.59 2960 143.6 1790 1970 0 0 0 0 0.95 0.95
77.98 3160 142.9 1780 1910 0 0 0 0 0.93 0.95
78.35 3400 136.8 1760 1840 0 0 0 0 0.94 0.95
78.76 3640 133.1 1760 1790 0 0 -0.8 0 0.94 0.95
79.14 3840 130.1 1750 1750 0 0 0 0 0.94 0.94
79.54 4040 125.6 1740 1720 0 0 0 0 0.88 0.89
79.91 4240 126.3 1740 1690 0 0 0 0 0.87 0.88
80.31 4440 129.3 1740 1690 0 0 0 0 0.84 0.85
80.69 4640 131.6 1730 1680 0 0 0 0 0.81 0.82
81.08 4840 131.6 1720 1700 0 0 0 0 0.8 0.82
81.45 5040 130.1 1710 1690 0 0 0 0 0.8 0.81
81.84 5240 128.6 1660 1680 0 0 0 0 0.8 0.81
82.24 5400 127.8 1620 1650 0 0 0 0 0.8 0.8
82.63 5440 26.3 400 1360 0 0 0 0 0.77 0.83
83 5480 16.5 310 1100 0 0 0 0 0.98 1
83.39 5320 17.3 320 1070 0 0 0 0 0.98 1

vwengineer said:

I have the AXX engine which has higher compression than BPY or BWA so it is highly sensitive to the octane level (VW advises to use only premium fuel but it can run on standard if needed). With standard unleaded it corrects up to 6.

Click to expand...

So your AXX has higher compression than the 10.5: of the BPY.

Mmm are you sure about this 10.5:1 number? AXX has 10.5:1 but it was made only in 2004 to early 2006. Then they redesigned it with different pistons and a compression of 10.3:1 which is the BWA engine which equips all GTI in Europe from mid-2006 to 2009. It is supposed that they did that for cost (I read that AXX had forged pistons) but also to improve the compatibility with standard unleaded fuel (AXX requires 98 RON octane by default while BWA requires 95). BWA engine map uses more boost than the AXX engine and supposedly has a bit more power, not sure if it's true or not.

Now the BPY engine I am not sure but I would have thought it would have been based on the second revision of this engine since the GTI arrived in the US in 2006. It also use the same pistons as the BWA engine (06D107066C vs 06D107066D for AXX) so I would think they have the same compression

AXX pistons:



BWA (BPY) piston:

Everything I have seen from VW show the BPY at 10.5:1.

Just had a look in ELSA:

AXX October 2004, 10.5:1, 98 RON, compatible with 95 RON with reduced performance
BPY March 2005, 10.5:1, 95 RON, compatible with 91 RON with reduced performance
BWA June 2005, 10.3:1, 98 RON, compatible with 95 RON with reduced performance

So BPY has an higher compression than BWA (different head?) but is actually compatible with lower octane fuel... Seems a bit strange, maybe the ignition is not as agressive (less efficient)? (all the octane ratings are RON ratings). I was also wrong about BWA requiring only 95 RON but it probably changes the ignition a bit less using 95 than on AXX.