Tune specific for "flex fuel"?

[Ritz]

The Shell station about a mile from my house just started selling 96 octane "flex fuel". The sign says it's 51%-83% ethanol and it's about 15 cents cheaper than regular unleaded. Is there a fuel map for the JB4 already setup for this grade of fuel? Maybe I'm not looking in the right places, but I didn't see one.

Best,

 

[turboAWD]

Look through the jb4 threads, and the CPI / fuel-it threads. In summary: stock - up to E15 should be ok. With jb4, you should be able to go up to E30 mix. E50 with jb4 + CPI. More than E50 is generally discouraged, so far. With stock parts, not enough fuel to run it safely.

But DEFINITELY read up. Just search for E85. Only 15 cents cheaper? Wow - although, you're already SUPER cheap. We're around $3.70 for a gallon here in NorCal, and E85 is around $2.80-3.00..

 

[Ritz]

Ah...thanks for the info. I should have spent more time searching.

Re: cheaper

Heh...yeah, I keep getting job offers in the San Jose/Sunnyvale area and can't believe how expensive everything is out there. My god....

Cheers!

 

[turboAWD]

Ah...thanks for the info. I should have spent more time searching.

Re: cheaper

Heh...yeah, I keep getting job offers in the San Jose/Sunnyvale area and can't believe how expensive everything is out there. My god....

Cheers!

Yeah, most things are relative - except cars. If you make 3x, houses are 3x, etc, a nice car like a Stinger is relatively cheap..

 

[eflyguy]

One reason I like Atlanta.. not the cheapest, but paid only $2.229 here yesterday (Costco, which is ~$0.40 cheaper than most places)..

 

[Ritz]

Yeah, most things are relative - except cars. If you make 3x, houses are 3x, etc, a nice car like a Stinger is relatively cheap..

Indeed. Anything close to the house I have now would be $2-3 million in the valley. No thanks.

Anyway, not to side track the thread....it would be great if there was a plug n play map for this particular grade of fuel, even if it meant changing the injectors or some other fuel system parts. If I was worried about the warranty, I wouldn't be here.

Best,

 

[Manaz]

You'd need a tune (or piggyback unit like the JB4) and also a flex fuel sensor to tell the tune/piggyback unit what the actual ethanol content is.

As I understand it though, the stock fueling system runs out of juice at anything above about E50 (in that it can't supply enough fuel to burn), which would mean you'd either be running much lower power levels (bad) or running lean (much, *much* worse).

 

[Soulection]

Interesting, is there a release day for BMS CPI?

 

[ecko04]

I’d test that fuel before dumping it into the tank. We’re getting close to the time of year where the switchover to fall/winter mixes start, which tends to impact the ethanol content.

It could be E83 today and E51 next week. Depending on what else you have in the tank you may end up with either too little or too much ethanol for the map you’re running.

 

[Manaz]

I’d test that fuel before dumping it into the tank. We’re getting close to the time of year where the switchover to fall/winter mixes start, which tends to impact the ethanol content.

It could be E83 today and E51 next week. Depending on what else you have in the tank you may end up with either too little or too much ethanol for the map you’re running.

This is where a flex fuel sensor is handy...

 

[ecko04]

This is where a flex fuel sensor is handy...

True, but still not foolproof. As you know, the flex-fuel sensors don't actually read the ethanol content but rather the absence of gas. If fuel is contaminated, let's say with water, the ethanol readings will be off. In actual application, the flex-fuel sensor really helps only after about 10 miles after a refill, once the fuel has had time to mix with whatever was left in the tank and has stabilized. It's virtually impossible to get an accurate real-time reading after an immediate refill and even more so when you're trying to achieve an accurate E30 mix. But once things have mixed and stabilized, the flex-fuel sensor is worth its weight in gold if only for validation purposes.

Even with the flex-fuel sensor, i'll probably still test my local re-fill stations once I switch to my winter wheels during my next oil change.

 

[turboAWD]

True, but still not foolproof. As you know, the flex-fuel sensors don't actually read the ethanol content but rather the absence of gas. If fuel is contaminated, let's say with water, the ethanol readings will be off. In actual application, the flex-fuel sensor really helps only after about 10 miles after a refill, once the fuel has had time to mix with whatever was left in the tank and has stabilized. It's virtually impossible to get an accurate real-time reading after an immediate refill and even more so when you're trying to achieve an accurate E30 mix. But once things have mixed and stabilized, the flex-fuel sensor is worth its weight in gold if only for validation purposes.

Even with the flex-fuel sensor, i'll probably still test my local re-fill stations once I switch to my winter wheels during my next oil change.

But if you have a jb4, for example, that can react to the instantaneous mix and "do the right thing", then it doesn't really matter that for the first mile, it's E15, then E20, then E32, etc... As long as you don't exceed E40/E50, you should be fine.

 

[ecko04]

But if you have a jb4, for example, that can react to the instantaneous mix and "do the right thing", then it doesn't really matter that for the first mile, it's E15, then E20, then E32, etc... As long as you don't exceed E40/E50, you should be fine.

I do not believe this to be totally accurate. We have to stop conflating CPI with other setups.

It is true that the JB4 samples more often than the vehicle’s sensors and can make adjustments on the fly, to keep things within the bounds of the vehicle’s sensors.

However, it is also true that the HPFP will max out much quicker than the LPFP. It is also true that ethanol flows at a much higher rate than gasoline, which exacerbates the aforementioned issue.

The JB4 when paired with CPI, which feeds off the LPFP, can handle ethanol mixtures up to E60, to bypass the HPFP falling flat on its face. Terry found the sweet spot for CPI to be around E50. This is only true when paired with CPI.

If you do not have CPI then the target ethanol mixture is E30. This is not to say that E33 or E35 will cause issues, but then we are creeping into an area where the HPFP will become strained. Worst case scenario, the JB4 will keep things tidy, and you’ll notice fuel pressure drops in the logs and/or timing being pulled.

Also, the JB4, as of now, does not alter the mapping based on ethanol content.

I am a believer that we need to do our own due diligence and stop depending on a product, in this case the JB4, to protect us from our own ignorance/arrogance.

If we know that the HPFP can max out, and we know we don’t have CPI — and even if we do, there’s no reason to run a mixture that our current setup cannot handle with the fallback of well the JB4 will save us.

 

[turboAWD]

I apologize if I caused any confusion between CPI and not - my goal was to post in general. I believe for CPI, the target is E50, but E60 is probably a good "do not exceed" limit, although Terry has run E100 with CPI. He's advised against it, but it sounds like, in a pinch, E100 wouldn't kill you if you had to drive 2-3 miles to get to another gas station.. That's WITH CPI.

Without CPI, I figured E40 was the danger zone, since everyone seems to say E30 is fine. If you want to say I'm off, and E35 is the cutoff, I won't dispute that.

However, I thought that the jb4 has an input for the fuel-it ethanol sensor and adapts based on it? It doesn't do map-switching, but if your ethanol content goes too low, it will default back to a less-aggressive map, or map0 (off)? I may have misread, though, and may be putting in too much of my understanding of how flex fuel works on a Subaru..

 

[ecko04]

I apologize if I caused any confusion between CPI and not - my goal was to post in general. I believe for CPI, the target is E50, but E60 is probably a good "do not exceed" limit, although Terry has run E100 with CPI. He's advised against it, but it sounds like, in a pinch, E100 wouldn't kill you if you had to drive 2-3 miles to get to another gas station.. That's WITH CPI.

Without CPI, I figured E40 was the danger zone, since everyone seems to say E30 is fine. If you want to say I'm off, and E35 is the cutoff, I won't dispute that.

However, I thought that the jb4 has an input for the fuel-it ethanol sensor and adapts based on it? It doesn't do map-switching, but if your ethanol content goes too low, it will default back to a less-aggressive map, or map0 (off)? I may have misread, though, and may be putting in too much of my understanding of how flex fuel works on a Subaru..

No, i'm not saying you're wrong about the E30 - E40 piece, i'm just saying if it's advised to not do so then we should try to avoid it and not put it out in the ethos that it's ok to do. I'm sure someone will lack the context that you and I have and run with a single post to believe it's the gospel without the background knowledge.

The JB4 does have an input for the fuel-it sensor as i'm using it. However, no it does not adapt to anything based on it. All it does right now is provide an accurate log that includes the correct ethanol level, not one based on the virtual reading, but it does not do any adaptation based on it and this is as of firmware v11, which i've been running since 7/24.

Based on your assumption, you would've thought that the JB4 would auto-tune based on the ethanol level, it does not. However, the same protections that are in place with the JB4 continue to be present with the inclusion of the fuel-it sensor.

 

[cncBilly]

I apologize if I caused any confusion between CPI and not - my goal was to post in general. I believe for CPI, the target is E50, but E60 is probably a good "do not exceed" limit, although Terry has run E100 with CPI. He's advised against it, but it sounds like, in a pinch, E100 wouldn't kill you if you had to drive 2-3 miles to get to another gas station.. That's WITH CPI.

Without CPI, I figured E40 was the danger zone, since everyone seems to say E30 is fine. If you want to say I'm off, and E35 is the cutoff, I won't dispute that.

However, I thought that the jb4 has an input for the fuel-it ethanol sensor and adapts based on it? It doesn't do map-switching, but if your ethanol content goes too low, it will default back to a less-aggressive map, or map0 (off)? I may have misread, though, and may be putting in too much of my understanding of how flex fuel works on a Subaru..

Can I ask what CPI is please. Thx in advance.

 

[ecko04]

Can I ask what CPI is please. Thx in advance.

Charge pipe injection. Basically, teeing into the LPFP and spraying directly into a bung either on the chargepipe away from the throttle body or at the intercooler. Think of it as adding another fuel injector to the system. It’ll help bypass the limitation of the HPFP. CPI is most useful for folks who have easy access to E85. Power is about the same as having WMI. WMI provides a superior cooling benefit. While CPI does cool, it doesn’t do so to the extent of WMI. Installation of CPI is done completely under the hood and doesn’t have lines to run to the back of the car and you won’t have to sacrifice a spare tire.

Stinger fuel system development

 

[Terry@BMS]

You can run up to 30% JB4 only and up to map5. For higher mixtures the high pressure fuel pump can't keep up so will require WMI or CPI. Fuel-IT has a CPI kit in production now, we have it on our development Stinger and it works nicely.

CPI is a 7th injector that mounts in a special bung you have to add to your intercooler piping or chargepipe, which allows the JB4 to inject extra fuel when the factory high pressure fuel pump isn't able to keep up.

 

[ecko04]

So basically what I said

 

[turboAWD]

You can run up to 30% JB4 only and up to map5. For higher mixtures the high pressure fuel pump can't keep up so will require WMI or CPI. Fuel-IT has a CPI kit in production now, we have it on our development Stinger and it works nicely.

CPI is a 7th injector that mounts in a special bung you have to add to your intercooler piping or chargepipe, which allows the JB4 to inject extra fuel when the factory high pressure fuel pump isn't able to keep up.

Do you do look at the E85 sensor input in the jb4? Or is it purely for logging purposes?