Ethanol sensor content changing during WOT affect AFR's?

[TAPyvehc93]

I am working on solving my issue of AFR's swinging out of my range of comfort during WOT. One thing that I did notice in my data log is that for some reason my ethanol sensor will sometimes get false readings during WOT. Will that have any affect on injector pulse width during a pull? Key on engine off the sensor is reading a stable 76-77 alcohol content. Under WOT I have seen it bounce to 60's, 50's, hell 39 lol.

[5FDP]

It's a real sensor right and not the virtual sensor that is useless.

[TAPyvehc93]

It's a real sensor right and not the virtual sensor that is useless.

It has the actual sensor wired in.

[realsquash]

It has the actual sensor wired in.

Is it in the supply or return line?

[schpenxel]

Yeah something's not right then. I've seen when there's no fuel going through them the readings change sometimes

Where is located?

[TAPyvehc93]

Its in the return line right off the rail.

[schpenxel]

Any possibility you're running out of fuel?

[realsquash]

Its in the return line right off the rail.

That's the problem right there. As demand for fuel goes up you will start having vapor in the return line along with the liquid fuel and your reading will be off. There are a couple ways to skin that cat, but running the sensor in the supply line is usually the best idea, if it works for your car.

[GHuggins]

That's the problem right there. As demand for fuel goes up you will start having vapor in the return line along with the liquid fuel and your reading will be off. There are a couple ways to skin that cat, but running the sensor in the supply line is usually the best idea, if it works for your car.

What other recommendations do you have if the return line is the only option? Restrictor of some sort or just better supply? What if you've got a dual pump kick In fuel feed setup - would you still have the aeration and drop out? Just wondering in case sensor moving isn't an option...

[realsquash]

What other recommendations do you have if the return line is the only option? Restrictor of some sort or just better supply? What if you've got a dual pump kick In fuel feed setup - would you still have the aeration and drop out? Just wondering in case sensor moving isn't an option...

As long as the pump(s) aren't cavitating you won't see a problem with vapor on the supply side. The return side is a tough one because the regulator itself introduces a lot of vapor, and if you don't have a completely filled line/sensor the reading is way off. You can put a restriction in the return side, like a very light (but high flow) check valve to try to help keep the return line at least full. The problem with that is if you restrict it too much the pressure regulator can't do its job and you get weird pressure fluctuations as demand changes, secondary pumps come on, etc.

Why isn't the supply side an option? It's the only correct place to put the sensor IMHO. If the sensor causes a restriction on the supply side that can be dealt with.

[schpenxel]

Yeah, can't be that big of a deal to add it to the supply side if needed. And the sensors flow quite a lot.. you'd have to be in the 1000rwhp'ish range for it to possibly be a restriction, and you can always Y the feed line, run sensor through one side

[LSxpwrdZ]

I never put them in the return line anymore due to this problem. The last car I had a sensor in the return line I set the volume delay to something like 0.1gal or more so that the content stays locked even if the sensor fluctuates. This gives you somewhat of a buffer but makes the sensor less responsive at the same time to actual ethanol content changes.

[schpenxel]

That's a good idea on changing the delay volume, assuming you aren't making 1 mile pulls or something

[GHuggins]

As long as the pump(s) aren't cavitating you won't see a problem with vapor on the supply side. The return side is a tough one because the regulator itself introduces a lot of vapor, and if you don't have a completely filled line/sensor the reading is way off. You can put a restriction in the return side, like a very light (but high flow) check valve to try to help keep the return line at least full. The problem with that is if you restrict it too much the pressure regulator can't do its job and you get weird pressure fluctuations as demand changes, secondary pumps come on, etc.

Why isn't the supply side an option? It's the only correct place to put the sensor IMHO. If the sensor causes a restriction on the supply side that can be dealt with.

I agree - I just wanted to know if there was a "work around" for when one might come in the shop in the future like this and now I know there is

This is the way I was fixing to install one - still technically on the supply side, but no risk of starving fuel before the injectors... And if this is who I'm thinking of - yes your AN fittings are larger in diameter internally than the said other main competitor - in fact your (-6) is right in between "their" (-6) and (-8) - guess only the external specifications are more or less mandated