fast951

Since you are getting the V-FLEX, all you have to do is flip a switch to go between pump gas and E85 (which will handle both fuel and ignition for you). You will be able to further adjust when needed with the PiggyBack. Since the Etahnol percentage in the E85 varies from one area to the next or during the time of the year, you will need a lambda meter to keep the AFR under control.

blown 944

Also, I have found that it is not bad at all to just either lower fp or just adjust the AFR to run regular pump in a pinch. I just got back from a 600 mile RT and I had to use a little pump (didn't really have to but was being cautious). It was over the Rocky Mountains and I had a ton of fun up and down the hills. I ended up not having to re fuel on the way back at all. This is the second trip I have taken this car on this year on almost all E85 and ~20-25 mpg.

Patrick, you may want to get a handle on what AFR scaling is going on. If you are in the 10s on spoolup it probably would feel sluggish. At full boost and ~ 25 degrees timing I run 11.4 or .78-.79 lambda. On spoolup I am much leaner than that with more timing.

MPD47

Can also run standalone with one of these:

GM Flex fuel sensor. 0-5v output based on ethanol content.

You can setup a modifier on certain standalone EMS' for ignition and fuel based on sensor output.

http://ttp-engineering.com/catalog/p...roducts_id=427

spoolin51

So simple and to the point.
yet 100% accurate

67King

I misread this the first time. I'm apparently not being clear.

There are three factors that determine how much fuel goes into an engine:
1. Amount of time the injector is held open
2. Pressure across injector
3. Flow rating of injector.

The fuel "map" isn't a map in the sense that it tells the injector how much fuel to put in. All it does is turn the injector on and off. Gives it a duty cycle, if you prefer. That ONLY impacts option number 1.

That leaves two other ways to get the right amount of fuel in an engine.

For example, let's say you have a 35pph injector rated at 39PSI. Sorry for the standard units, it is what SAE uses. So, say you need 35 pounds of fuel. Turn on the injector for 1 hour. Yes, that is preposterous, but it makes the math simple.

Well, what happens if you need 52.5 pounds of fuel?
1. One option is to change the map. Command the injector to stay open for 1.5 hours. That is what I am inferring you are saying is the only way.
2. You could jack the fuel pressure up buy a factor of 2.25 (fuel flow increases with teh square of pressure increase). This is pretty impractical, though, at nearly 90 PSI across an injector (under boost, this would exceed 100PISG!).
3. You could just replace the 35pph injectors with 52.5pph ones.

I am saying that taking route number 3 is a viable option. The engine will NOT go boom - assuming your fuel pump can handle the volume (this is what I thought you were getting at). It still gets the EXACT same amount of fuel as it would if you left the injectors alone, and manipulated the map.

This is what my friend with the beater Saab did. He then cranked up the boost, and it ran like a raped ape. This is also a VERY common thing you see in the aftermarket. Ever heard a term to the effect of "MAF calibrated for ## pound injectors?" That is almost the exact same thing, but in reality, less precise. They resize teh orifice for the heated wire, which tells the computer the engine is seeing less air than it really is. So, the computer thinks the engine is at a lower load point, therefore picks off a different part of the "fuel map," and closes teh injector sooner. But, as you put in bigger injectors with teh MAF, you still get the correct amount of fuel.

Precise? No. Optimized? Hell no. Effective. Yup. Would I advise anyone to do it? Nope.........except in the context here where the poster was afraid he'd be stranded if he couldn't find ethanol. Just threw it out as a simple way to get around the problem.

CarbonRevo

So you're saying that if I'm stranded somewhere with only pump gas to use...I should change out my injectors?

Lol...I'm sorry, but Spare injectors aren't something I carry in my glovebox. Would rather just flip a switch or do a quick re-tune.

porshhhh951

I'll just flick my FQS switch in the cabin thankyou very much. If I need it fine tuned from there I'll open my notebook, not the hood.

blown 944

I say this with all sincerity, I have literally had to stop and put pump in a few times over the years and it was as easy as lowering the FP or adjusting the AFC.

Again I just did this last weekend. It is really not that bad.

Obviously, having a separate tune is the way to go, but honestly..... Who's to say that it will be perfect for a mixture?? You will still have to tune slightly anyway depending on how much pump vs fuel is present.

Myself I have just found that running on E85 99% of the time works the best and just change the tune (via pressure or AFC) when I need to use pump gas. I have done this with stock injector size, 76# , and 96 # injectors. If the chip is mapped for the injector size the adjustment to get a good tune for E85 or pump is really minimal.

I am still unsure why everyone makes this out to be so difficult???

I may just have to stay away from this thread for awhile until more folks actually switch, and see how easy it is. There are a few ways to skin a cat regarding changing the fuel increase necessary. You don't have to have the latest and greatest software to do so.

Hell I ran around for well over a year on the stock injectors and only had to touch the FPR 4 times at most to compensate for the type of fuel.

CarbonRevo

I just don't want to have to rely on something like that as a common fix. I mean....if it the last resort, I would not have a problem doing so. I'm sure it is easy like you say, but I haven't seen it done and surely don't want to be the test mule.

Adjusting pressure might not be bad...but switching injectors out? Ha...no thanks.

67King

Hey, you asked if you would have to change your tuning, you didn't put any constraints on it! You don't have to like my answer, but sheesh, what is it about human nature that causes negative reactions when people don't like answers to questions they asked?

Seriously, I thought you were averse to a retune. That means either fuel pressure or injectors. Upon further reflection, though, as Blown 944 states, adjusting the fuel pressure is a quick, easy solution. And as you are trying to reduce flow, rather than increase it, reducing pressure should be a lot easier than increasing it. So that probably is the best way to go (without a retune).

I guess having driven a 25 year old Pontiac, then a 25 year old Olsmobile in college, then later on, a 15 year old project European Ford desensitized me to keeping tools and spare parts with me.

333pg333

Just to digress, and not to call your knowledge into question as you clearly have done a fair bit of reading, but if you say the above statement and someone decides to 'give it a go', it could clearly finish in disaster. By merely swapping out inj you will not have any hope of supplying enough E85 to run the right mix. Even by slapping on a larger fuel pump isn't ideal either. I realise that you weren't making an absolute statement, more an off the cuff remark, but if the wrong person reads it and thinks it's ok to do this and their engine blows, who is going to pay for it? My guess is it won't be your friend with the Saab nor you.
I also don't think people are taking what you say badly and having a negative reaction. Clearly people will opt for the ease of use option rather than wanting to pop the hood.

pjburges

It was mentioned above that the tolerance held on the fuel content (mixture) regarding ethanol is pretty poor. I could see how you could get around that with one of those GM sensors, but wow - Id expect them to be mixing this stuff with gas pretty accurately for the sake of production and whatnot....

Has this been others' experience with E85 so far? Is it more like E63-E91? Id be worried about getting too poor an octane fuel for a really extreme race mapping - or too much ethanol and not being able to lubricate the upper end of the motor....

blown 944

It has been my experience that the ethanol content seems to be pretty stable.

I have filled up at ...counting.... _13_ different stations from the North Denver metro area, to Alb NM, to the western slope (Grand Junction). Using my knock counter and wideband for reference I have seen no difference in performance.

My philosophy goes, that if it has a full e85 mix run whatever boost I want. If I have any pump in, I limit boost to 15psi until next fillup.

Actually 14 I forgot I once filled in Ft Collins .. Make that 15 from the souther station in Parker........ Hell if I keep thinking, I bet I have filled at over 20 stations.

eniac

I will confirm everything Sid has stated in this thread. Listen to him, I have done many of the same things myself. I have been putting a TON of miles on my car this summer and 95% of the time it's with E85. These miles are 1000 - 1500 a week and includes a few track days.

I rarely have to make an adjustments with E85 in between fill ups. I get gas at Meijer since they have the most E85 stations in Michigan. My knock counter seems pretty consistant in between fill ups.

There have been a few times I was low on gas and could not make it to the nearest known E85 station so I had to put in Premium. The easiest way for me in that case is to run the E85 out as much as possible and fill with Premium. The ONLY two changes I have to make are:
1. To turn my boost down which my EBC has an A/B setting. A is set to 27/30 psi, B is set to 18/22 psi.
2. I simply scale my overall fuel map down 15%

This is not optimal however the few times I get stuck and have to run premium, I am on a trip and driving mostly on the highway. The speed limit is 70mph and I typical drive 80-90mph so it's basically slow cruising and easy on the car and engine.

I switched to E85 last summer and 20,000 miles later I still can't figure out why anyone would not switch to it. I'm not sure how many fill ups there would be in 20,000 miles(~50?) but I am sure that less then 10 of those were on premuim, the rest were all E85.

95ONE

.. what they said..

Once again.. mixtures are different at different types of the year on PURPOSE! Colder temps = slightly harder start for e-85. So the winter mixtures are PURPOSELY less E-85 with more fuel..
It also depends on where you are geographically. Here in Houston, colder temps aren't a problem.. Ever. So it's almost always an 85% mix.

And yes.. if you have two programs in your ems, it's just a matter of flicking a switch.. It really is that easy..

You know, this is funny.. If Alcohol were the norm, the argument to go to petroleum based would be way worse, with a whole lot more difficulty's to do.. Engines would be built with higher compression ratios that burned more efficiently and wouldn't be able to burn the crappy petroleum fuel. Think about it.