How much latitute in stock ecu for low blend E85 flexfuel?
 

Did a search and couldn't find an proper answer and decided this was the best place to ask my question as the expertise should exist here.

Let me explain the situation. 93 octane (98 ron) is hard to find here, and there is plenty of E10 and E85 available where I live. And 93 is 60% more expensive than E85. So I see a window of opportunity to get the stock engine running properly with a blend of E10 (89 octane) and some E85. And, believe it or not, I do care if I can reduce oil dependency and reduce some Co2 emission also. If this could work it seems a win-win. Oh, I don't feel like running 100% E85 which I have considered of course, both because I am not sure about long term issues and because I don't want to fiddle with computers reflashing my ECU and all that.

So I am asking you experts here, on a stock NA car, how much latitude is there in the stock programming to run a higher blend than E10? Not thinking power gains here (but always welcome ;) ), but rather how much can the ECU adjust fueling so that the engine doesn't run lean, which I see as the main danger. How does the ECU adjust, does it read a real lambda... The stock car runs very rich above 6000rpm so assuming that fuel delivery capacity itself won't be a problem.

Also, is there any immediate danger in experimenting, will the ECU protect the engine from running lean? As knock sensitivity should decrease I don't see an issue on that account.

Purely mechanically a low blend is safer than a high blend... won't go higher than E50 for that reason alone, that is sure already. Also, quite a few people over here run E50 (50:50) or even E85 on stock gasoline cars, but their cars aren't new and don't have high compression, part-DI and 100hp/litre...

Thanks for reading and perhaps taking your time to answer my inquiry to your best knowledge :)

There aren't any significant long term issues that have been proven to be directly correlated with 100% E85 usage on this platform; check out this thread: http://www.ft86club.com/forums/showthread.php?t=64621

I am by no means an expert but my Moto-East Flex Fuel Kit took me about two hours to install and flash the tune which required no fiddling what so ever. The whole kit is plug and play with high quality, factory spec fittings and pre-built ECU harness. The EcuTek ProECU software is as easy to install as any other Windows program and flashing the tune is as easy as plugging in a cable to your OBD2 port and pressing a few buttons and it's done flashing in a few minutes. I couldn't think of a better solution for you, unless the real reason you're avoiding it is the cost, which is very small compared to a new engine if you blow yours while running higher than 10% ethanol content on the stock tune.

As to your questions about the risk using guesstimated blends of up to 50% ethanol on a stock tune, I can't imagine that wouldn't cause issues running too lean. I wouldn't risk it when there is no reward aside from saving a little money at the pump. The FF kit and tune would maximize power and safety and add the convenience and piece of mind knowing the car is running perfectly with the correct timing and AFR that's been adjusted on the fly based on the actual ethanol content in the lines.

Thanks, I was aware of this kit. I've flashed plenty of cars before, I know how it's done. Without getting into detail, I just don't want to open that door...

Getting Tuning done to support flex fuel or e85 is your only option. Running e85 or e10 on the stock ecu will be asking for trouble in the long term maybe even short term. A flex fuel kit sounds like your best option if you want to be putting that type of fuel in your car.

You dont want to deal with having to fiddle with computers and reflashing, but you want to sit there and try and calculate a proper e85/93 fuel mixture everytime you fillup?

Like the others said, just go with a tune/flex fuel kit. Or openflash (My method of tuning). The tune/flashing for this car really is simple.

It will be much simpler, safer and better for you in the long run.

Yes I understand and that is a nice piece of kit.

But for the original preposition not knowing the relevant facts, the careful/sensible thing to do would be to refrain from it. But I'm just curious and would like to hear, if it is a bad idea, exactly why it is so.
Most modern cars will adjust fuelling to match the tabled lambda which is independant of fuel type... Neither am I looking for a performance gain, just a 'street smart' alternative to fuel my car with a matching octane number...

Fuelling up with a certain mix is dead easy, I can do grade school math and the fuel nozzles sit just besides eachother at our gas stations...

Oh, and people that run 100% E85 in performance applications here (northern europe) like to use a friction modifier additive, adding that is just as much a hassle as mixing...

Okay well you already know it's not smart at all to do what you're proposing since its extremely risky and could easily damage your engine. You'd be better off just using Torco Accelerator if your true goal is to increase the octane rating of the gasoline available to you. I've used it before on the stock tune with good results. It's the only octane booster that actually works and isn't composed of a bunch of kerosene and MMT. Torco is actually concentrated race gas.

Engine oil or fuel additive? Do you have any other data about that because I've never heard of that being absolutely necessary for a performance application. I do use Lucas Ethanol Fuel Conditioner once in a while as a preventative measure.

Ok.

Some more background. People have been experimenting with blending for over a decade here. If works on many engines with blends of E20 to E50 without reflashes. Including GDI and FSI engines. So it can definitely work long term. Question here is engine specific risk... For that matter, people have by mistake run their engines on E85 with a gasoline map and their engines didn't go bang...

Alsox fuel prices are completely different here. With a E30 mix (~92 octane) I would save 15$ a tank. Even accounting for decreased mileage, that is approx. 10$ a tank or 500$ a year since I fill up every week. Not a massive saving, but not insignificant and with a smaller environmental footprint too. And better availability also...

So still wondering if anybody can answer the original questions on how the ECU works in this matter...

You may save money per tank but you take a mpg hit. Running e85 I'm floating between 20-22mpg and running 93 I get 28-30 mpg. Less money per fill up but filling up much more often. With pricing here it kinda breaks even.

The stock map like tuned maps can adjust for differences in fuel density usinf fuel trims. The ltft and stft have a range of about 20% but this can be adjusted in tune.

The stock tune cpoes with E10 this way and the manual states car is fine on e10 blend fuels.

I would imagine it would adjust to e20 or so but after that your fuel trims would be getting fairly high. If you wanted to try it you would need to be able to monitor your long term fuel trims and AFR . Although its slow you could probably use android torque app and a cheap elm327 adapter.

You would not want to go much past ltft od say 10 to 15% and check you afr is adjusting back to close to stock values throught rpm range.

The oft e85 tune uses this method to adjust between E60 and E85 with no flex fuel kit however they may have made some tweeks to learning values in tune

You might be able to go past e20 but that going to be your call

As othrs have said you going to take a mpg hit as ethanol has less energy value per volume than petrol

Thanks, this is the kind of feedback I was looking for. I can monitor through the Torque app.

I am well aware of increased fuel consumption, I already adjusted for that. Different locations and usage patterns result in different priorities, we share a car and an interest in how it works ;)

torque will monitor fuel trims and afr , its refresh is too slow for tuning but is ok to get a general idea of what is going on, you should not run into knock problems as ethanol is highr octane.

no guarantees here is all your call

Fully understood. Just want to gather as much qualified input as possible before considering actually trying this...