Flex Fuel Kit?

[Powersfrs]

Who's doing this?? Tell us namesss

[whitefrs]

Originally Posted by Powersfrs

Who's doing this?? Tell us namesss

Doin wat?


I love boost!!!!!!

[jamesm]

I'm not out to hatchet job anyone, but suffice to say there's only one that I know of. It's simple, just look at your trims. If they're off you'll notice it's pretty apparent., ie you'll have a steady +15% stft and no ltft. And your car will probably drive like crap around town lol.

[steve99]

Originally Posted by jamesm

Good call. Going to get a gauge now that you mention it lol. Or maybe an led could suffice. I really just don't want a gauge in my car. Rice rice baby lol. Maybe keep it in the glove box if my led idea doesn't work out.

Actually couldn't you theoretically set another custom map with a threshold below say 5 or so (whatever you'll never realistically be under as far as ECA) on the other custom map's output (ECA scaler) then just have that map trigger the cel and do whatever else you want? If you do activate below threshold ~5 (or 2, or whatever) you'll only activate if it goes open unless you put ethanol free gas in the car, which I don't think I've ever seen around here. Just an idea.

Just trying to get my head around the basic operation of these flex fuel kits.

1. you need a "spare" input sensor to "hi-jack" eg second O2 or some other non essential input sensor.

2. Flex fuel sensor is connected in to spare sensor input.

3. ROM needs extra code or changed code to interpret the new input from the flex fuel sensor.

3. Depending on the input read from flex fuel sensor input (I assume its calibrated for Ethanol content) the ECU via changed ROM code can

Automatically switch between maps eg low/med/high ethanol content or does the new code make continuous scaling adjustments depending on ethanol content or a combination of both ??

The Guage or indicator LED you talking about would be driven of an ECU output or some electronics directly off the flex fuel sensor input ?? or the ECU is coded to throw a CEL code/light when ethanol content is out of range ??

Thanks

[jamesm]

Originally Posted by steve99

Just trying to get my head around the basic operation of these flex fuel kits.

1. you need a "spare" input sensor to "hi-jack" eg second O2 or some other non essential input sensor.

2. Flex fuel sensor is connected in to spare sensor input.

3. ROM needs extra code or changed code to interpret the new input from the flex fuel sensor.

3. Depending on the input read from flex fuel sensor input (I assume its calibrated for Ethanol content) the ECU via changed ROM code can

Automatically switch between maps eg low/med/high ethanol content or does the new code make continuous scaling adjustments depending on ethanol content or a combination of both ??

The Guage or indicator LED you talking about would be driven of an ECU output or some electronics directly off the flex fuel sensor input ?? or the ECU is coded to throw a CEL code/light when ethanol content is out of range ??

Thanks

Flex fuel is set up like any other custom map using an external 0-5v input. First, you create a scaling map that takes the 0-5v signal and resolves it to ethanol content, in the case of zeitronix just a straight 0-5v, 0-100% interpolation iirc. You can then use this custom maps output as an input to any other custom map, so you'd set up additional one to compensate for cranking ipw, fuel quantity (to compensate for density), afr target, timing, boost or whatever else you want to vary based on ethanol content.

[Powersfrs]

Originally Posted by whitefrs

Doin wat?


I love boost!!!!!!

What tuners are known to disable knock

[DSTL]

Eh. My experience is totally different. I usually use an e70 map and test fuel frequently to add the appropriate amount of gas to "e85" to make it true e70. It runs waaaaay better than running on an e85 map that is "close" to actual fuel and letting the ECU make up the difference. I'm thinking of going flex fuel this spring because it's a PITA to test all the time and the performance difference is so noticeable.

Originally Posted by Sportsguy83

Depends on your goals. If you are going to stay N/A, I would not do FF.

Only thing to keep in mind is always switch to the required map and always try to empty tank as much as possible before switching.

Wether you end up with E18 or E65 (because you did not completely drained the tank and had some fuel left over before switching), the ECU will adapt via Fuel Trims to that.

If you plan on going FI, I would highly recommend it.

Of course, this is IMHO and from what I've seen and learned with this car.

[DSTL]

I've done this. Car feels like you're pulling a heavy trailer up a steep hill and makes a lot of racecar noise. It lets you know something is wrong. Mine still runs fine it didn't break it. I can also say that running at e60 on an e85 tune means you are getting crappy mpg with less power than just sticking to pumpgas. This is where the flexfuel systems shine. They would be pulling extra power in this scenario.

Originally Posted by jamesm

I agree flex fuel is a serious improvement over running two maps, and is great to have, but id be shocked to see an fa20 actually blow up due to low ethanol content e85 or even regular gas on an e map. The ecu would pull a ton of timing, throw the cel and go into limp mode before that could happen. Of course I've never seen it happen, but just given the hyperactivity of the knock control and it's operable range, and how limp mode works, it seems incredibly unlikely. If you made it through the first wot pull you'd be in limp mode by them, and you'd notice a problem before you ever made that pull just from the drivability.

Not saying it's a good idea, but at the same time it's a bit alarmist to suggest that normal e content variation would cause catastrophic failure without it.

Now if your tuner is a moron and disabled knock control, all bets are off.

[Sportsguy83]

Originally Posted by DSTL

Eh. My experience is totally different. I usually use an e70 map and test fuel frequently to add the appropriate amount of gas to "e85" to make it true e70. It runs waaaaay better than running on an e85 map that is "close" to actual fuel and letting the ECU make up the difference. I'm thinking of going flex fuel this spring because it's a PITA to test all the time and the performance difference is so noticeable.

I am not suggesting not going FF is better or anything similar. If anyone has the money to go FF, its a no brainer. What I am saying is, the car will not blow up if you get a bad batch of gas as long as the fuel trims are working and not turned off by your tuner. The ECU is good enough and in a few minutes it will adjust via fuel trims. Doesn't mean I encourage it, doesn't mean the car will drive 1000% perfect.

I honestly don't see how a tune for E85 would be waaaay worse powerwise than running a tune for exactly E70 on an N/A car, given that with an E85 tune you would probably have one more degree of timing and when you put E70 on the car it will not knock, thus will not pull timing.

If you run an E70 tune, it already has the degree of timing removed, you will not ever make the power the E85 tune made. (I am using one degree of timing as an example, might be half a degree of timing or something similar).

Hope that made sense and please take this with a grain of salt, no expert here....

[jamesm]

^this. No one is saying that running e70 on an e85-optimized tune is... optimal. The point is that it's not going to cause any damage. The car won't knock itself apart. Of course it will make less power than if it had e85 in it.

The same goes for pump gas even, to a lesser degree. If having your wife or someone screw up and put 91 in your tank when the car normally runs 93 causes damage, it means your tune was too aggressive to begin with. The factory knock control system should handle that case with no problem. Everyone running and oft ots tune on 91 is relying on the factory knock control system, right now (really, check your iam lol).