[Glowin]

Totally new to using ethanol, so bear with me please! First time using it yesterday as it just became available in my area.

Two questions:

1 - I know I'm supposed to log and make sure all is good, and will do so, but I was wondering, the E30 maps require at least E30 blend, or as close as you can get to it? I realized after I filled up yesterday that the mix I've ended up with is probably about E50, so was wondering.

2 - Also, what happens if you run the regular maps on a higher concentration of ethanol gas? Is it actually bad for the car, or you just don't take advantage of the extra power you could have by not running an E30 map? I'm thinking if I have E30 in the car, and need to fill up, and don't have E85 around, so the new blend becomes E20 let's say, then what happens if I go back to the regular 2+ maps?

My car's got stage 2+ mods.

[UMich_335i]

I would imagine your main concern would actually be your lpfp. The stock pump may not be able to handle the additional fuel request so watch your lpfp pressures to make sure you don't get sustained drops in the low 60s or 50s.

[Jeff@TopGearSolutions]

Originally Posted by UMich_335i

I would imagine your main concern would actually be your lpfp. The stock pump may not be able to handle the additional fuel request so watch your lpfp pressures to make sure you don't get sustained drops in the low 60s or 50s.

I agree, the concern with too high of E85 is the LPFP not being able to keep up.

Going down to E20 by no accident may not have enough octane for the more aggressive map.

[Glowin]

Thanks. So I'll drive it easy for the next little while, til I can fill up with E10 and get the mix close to E30. I thought that maybe it would be ok, just that the car's not taking advantage of the higher ethanol content. Sort of like running race gas 100 octane on a 93 octane map. From what I understand, it's ok, just that it's a waste since the higher octane isn't really being taken advantage of.

If I'm at E20 at some point, now that I think about it, I guess the regular maps are designed for a max of E10, so I should again take it easy until I can even out the mix.

[UMich_335i]

Originally Posted by Glowin

Thanks. So I'll drive it easy for the next little while, til I can fill up with E10 and get the mix close to E30. I thought that maybe it would be ok, just that the car's not taking advantage of the higher ethanol content. Sort of like running race gas 100 octane on a 93 octane map. From what I understand, it's ok, just that it's a waste since the higher octane isn't really being taken advantage of.

If I'm at E20 at some point, now that I think about it, I guess the regular maps are designed for a max of E10, so I should again take it easy until I can even out the mix.

You don't want to lean out no matter what gas you are running, so its safer to have a slightly higher ethanol content than not enough for combustion purposes. Search for the "e85 mix calculator" on your android phone for help with mixing amounts.

[AmonFire]

Here are the things that you need to look out for while running high concentration ethanol blends. I'll also include some pictures from an e50 log of mine.

Fuel Trims:

Make sure you monitor your Short Term Fuel Trims (STFT) for banks 1 and 2. This is a measurement of how much the fueling system has to compensate percentage wise to supply sufficient fuel for the engine. The N54 can run up to +34% compensation for supplying that extra fuel. If you hit 34 you've completely tapped out the cars ability to supply fuel and you run the risk of leaning out your mix and possibly damaging your engine. You can see that I peak out around 16% extra fueling demand.


Timing Corrections:

Check your corrections for cylinders 1-6 and see if there are any spikes into the negative numbers. More than around -3 is a concern. This indicates that premature detonation of the fuel mixture has been detected and the engine is easing up timing as a result. My DME is happy and does not need to correct timing anywhere through my pull.


Fuel pressures:

Compare the pressure the DME is requesting from your Low Pressure Fuel Pump (LPFP) and High Pressure Fuel Pump (HPFP) and the pressure they are actually producing. This will let you know if your fueling hardware is not up to the task you are asking of it. I'm currently maxing out my LPFP on the top end and this is with an upgraded 450 LPH pump.


AFR:

Just to be safe you can monitor your AFR to see if past all the other sensors your engine is running lean. Our Direct Injection engines idle a little leaner than people are used to at around 14.7:1 and will probably worry a dyno operator if they're not used to DI engines. At full throttle my tune keep me around 12:1 which is nice and safe.


If you have any questions just let me know and I'll explain the best that I can.

[UMich_335i]

Pretty impressive use of your 3rd post!

[BoostedE90]

Nice post AmonFire! Probably one of the most informative/helpful posts I've seen on this forum in a long time.

And way to knock it out of the park on your 3rd post

[UMich_335i]

When upgrading pumps you can also just add an additional 255 inline pump like SteveAZ offers. I chose to go this route and it has proven to have plenty of extra pumping power to meet demands.

[Jeff@TopGearSolutions]

Originally Posted by AmonFire

Here are the things that you need to look out for while running high concentration ethanol blends. I'll also include some pictures from an e50 log of mine.

Fuel Trims:

Make sure you monitor your Short Term Fuel Trims (STFT) for banks 1 and 2. This is a measurement of how much the fueling system has to compensate percentage wise to supply sufficient fuel for the engine. The N54 can run up to +34% compensation for supplying that extra fuel. If you hit 34 you've completely tapped out the cars ability to supply fuel and you run the risk of leaning out your mix and possibly damaging your engine. You can see that I peak out around 16% extra fueling demand.


Timing Corrections:

Check your corrections for cylinders 1-6 and see if there are any spikes into the negative numbers. More than around -3 is a concern. This indicates that premature detonation of the fuel mixture has been detected and the engine is easing up timing as a result. My DME is happy and does not need to correct timing anywhere through my pull.


Fuel pressures:

Compare the pressure the DME is requesting from your Low Pressure Fuel Pump (LPFP) and High Pressure Fuel Pump (HPFP) and the pressure they are actually producing. This will let you know if your fueling hardware is not up to the task you are asking of it. I'm currently maxing out my LPFP on the top end and this is with an upgraded 450 LPH pump.


AFR:

Just to be safe you can monitor your AFR to see if past all the other sensors your engine is running lean. Our Direct Injection engines idle a little leaner than people are used to at around 14.7:1 and will probably worry a dyno operator if they're not used to DI engines. At full throttle my tune keep me around 12:1 which is nice and safe.


If you have any questions just let me know and I'll explain the best that I can.

This should be a sticky on it's own!

[C.Pop]

I ran the OTS e30 map with a tank of e50 and the car didn't like it that much; it ran a little lean. I wouldn't call it unsafe, but it's not ideal. It's very easy to adjust your fuel scalar on the OTS e30 map to make it e50, which is what I did and I recommend you do. I'm also something of a stickler for maintaining whatever e% blend you choose, not just "eh... close enough" and go.

[stanlalee]

If your fuel pump is up to the task change the fuel scalar accordingly. It won't hurt anything if your fuel pump is up to the task other than leaving power on the table running a conservative (for e50) tune.

[Eat.Sleep.Race]

Originally Posted by UMich_335i

Pretty impressive use of your 3rd post!

Heck yea! Nice share!

[Glowin]

Originally Posted by stanlalee

If your fuel pump is up to the task change the fuel scalar accordingly. It won't hurt anything if your fuel pump is up to the task other than leaving power on the table running a conservative (for e50) tune.

For someone who hasn't used AccessTuner Race before, just learning how to tweak the fuel scalar, how many hours you figure it will take?

Or to do just that, you've got to read up on a bunch of other things too and tweak them all? I know nothing about load, WGDC, etc. tables...

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@AmonFire thanks!

I've got an idea of the stuff you're talking about, from hanging out here and reading the Cobb logging notes, but this is a great visual summary.

1 - So the STFT is more important to log than the LTFT?

2 - Do the fuel trims and fuel pressures tell you different things? I'd have thought if you're maxing your STFT, it means you're not getting enough gas (and therefore not enough pressure).

3 - Can one thing be ok, while the other isn't? ie 15% STFT but max pressure. What would that tell you?

4 - Or 30% STFT, but pressure is fine. What about that?

[C.Pop]

The problem with just looking at fuel trims is that they can get confused sometimes, especially when changing maps to ethanol mixes. Look at both your LTFT and your STFT. I've seen STFT's at +34 but LTFT at the same point at -30, which means you have diverging trims, not that you're maxed out. A simple log will tell you much. You can reset fuel adaptation via INPA or Bavarian Technic. It does not reset with an ECU reset.

Learning AccessTuner Race, the fuel scalar, will take you about 5 minutes. It's very easy, it's just one table. SteveAZ showed me and I had no issues at all when I wanted to run an OTS map but had e60 in my tank.

[themyst]

in my personal experience, E50 blend on stock turbos should be ok. Change fuel scalar and monitor STFT to confirm under heavy load. Generally speaking you can probably get away with a global 0.5 - 1 degree of additional ignition under E50 vs E30, although every car is different.

On upgraded stock frame turbos, no dice; your LPFP will take a dump at E50.

[stanlalee]

Originally Posted by Glowin

For someone who hasn't used AccessTuner Race before, just learning how to tweak the fuel scalar, how many hours you figure it will take?

Or to do just that, you've got to read up on a bunch of other things too and tweak them all? I know nothing about load, WGDC, etc. tables...

No hours. Start with Cobb fuel scalar table for e50 across the board except the high load/rpm points of the table (4500rpm up at 180 load) adjust it a little higher (e55-e60 per table) OR just proportionately raise the values based on the e30 map for e50 (using the scalar table as a reference). From there its just a matter of going up/down based on fuel trim logs (going up should lower fuel trims if its possible). Your not really tuning just compensating for the stoic difference between gas and ethanol mix.

[AmonFire]

Originally Posted by Glowin

For someone who hasn't used AccessTuner Race before, just learning how to tweak the fuel scalar, how many hours you figure it will take?

Or to do just that, you've got to read up on a bunch of other things too and tweak them all? I know nothing about load, WGDC, etc. tables...

--------------------------------------------------------

@AmonFire thanks!

I've got an idea of the stuff you're talking about, from hanging out here and reading the Cobb logging notes, but this is a great visual summary.

1 - So the STFT is more important to log than the LTFT?

2 - Do the fuel trims and fuel pressures tell you different things? I'd have thought if you're maxing your STFT, it means you're not getting enough gas (and therefore not enough pressure).

3 - Can one thing be ok, while the other isn't? ie 15% STFT but max pressure. What would that tell you?

4 - Or 30% STFT, but pressure is fine. What about that?

1 - They are two different measurements of the same value but with completely different connotations. STFT are for the immediate trim values the DME is currently running. LTFT values are learned over time and are more of an indicator how the DME is overall adjusting itself to run a certain fuel mixture. This is why resetting your fuel adaptations like C.Pop said is a very important step if you plan on running a certain mix for the foreseeable future rather than just a single fill up for a glory dyno run or something. Your LTFT will stay adapted for a decent time to the previous mix of fuel you were running and could negatively affect your performance.

2 - Yes. I am not an expert on these things so someone can correct me if I'm wrong. As I understand it fuel trims are not measuring extra or reduced load/demand on the fuel pumps. They are in fact a measurement of the time the DME keeps the fuel injectors open. This is why there is a limit of +34/-34 %. The injector hardware can only decrease or increase its fueling window that much before it runs into its limits.

3 - I assume by max pressure you mean your pumps are running past capacity and not supplying the fuel the DME is asking for. You should ask tuner about that rather than me, but check your AFR and timing corrections. If you're not getting any knock and your AFR is in a safe area I wouldn't worry about it.

4 - 30% trim is still within the DME's capabilities and the pressures are fine so technically I guess that's okay. I myself would like to run a little less trim. With properly adjusted scalars and a fuel mix your hardware can actually support I personally would like mine to be under 20. But really, like I said about 3, you should be asking an actual tuner about that.