Continental Flex fuel sensor

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jasaircraft
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Continental Flex fuel sensor

Post by jasaircraft »

Hi so im trying to get a reading from a continental flex fuel sensor my client bought, i have 12v on vcc, ground on gnd, and the Vout to my ms3 input which is js07 but cant get a reading,i also get "flex fault" flashing.
For the test i placed a measured jar with alcohol and a fuel pump with return back to the jar. The sensor is i the return line. Maybe it has a sense of flow or should i use 5v?
So its a small fuel circuit.
Last edited by jasaircraft on Fri May 19, 2017 1:27 pm, edited 2 times in total.
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

I cant see any part numbers
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

I also found it strange to have a ground on the VCout, i was expecting a 12v from a 12v pullup...
Edit: it should be 5v from pull up according to page 39 of the hardware manual, i have the 10k resistors installed as in that page.
I also saw a diagram from continental which stated the pullup should be from 1.3kohm up to 5kohm and lower would yield a fast output rise time and viceversa, maybe i should try with lower resistor values?
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jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

According to AEM flex fuel sensor (which looks exactly the same) specs they use the same frequency and pw specs that are default on tunerstudio.
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

How can i test both the ms3 input and the sensor separatelly?
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

Ok today i tried using a 12v pull up with 4700ohm resistor on the signal wire (keeping the inside circuits as the manual states) and nothing no signal just flex fault sign.
Then i installed an expansion board to use the dedicated flex in.... nothing, tried with and without the 12v pullup.
Then i tried with a second sensor and still nothing (did not try with 12v pullup with this second sensor).
So im out if ideas.
Should i see 12v from a pull up on the expansion board's flex in pin?
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Re: Continental Flex fuel sensor

Post by jsmcortina »

The Flex input is 5V MAX. Do not apply 12V to the input.

I've tested before using a "Generic PWM" frequency output on PT4 connected to the Flex input.

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jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

jsmcortina wrote:The Flex input is 5V MAX. Do not apply 12V to the input.

I've tested before using a "Generic PWM" frequency output on PT4 connected to the Flex input.

James
Hi James
Today i tried using the PT4 like you said and both flex in and JS7 inputs read the signal OK. So I can discard a problem in the ecu.
Could it be that the difference is that PT4 outputs a 5v pwm signal and the sensor is a 12v pwm signal?

My wiring as far as I have checked is also ok, sensor gets 12v, tried ms ground and chassis ground, signal wire(Vout) from sensor has good continuity up to the 10k resistors inside.
So either there is something wrong with these two sensors or the alcohol....

Does the sensor have to have flow through it or can it just be submerged in alcohol? does it have a sense of flow?
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

Ok so i found my problem...
Turns out this alcohol wont mix with gasoline, they separate.
Trying to measure pure alcohol wont put out a valid signal apparently and it measures "1% flex fault"
When there is a little air in the sensor's tube it will put out a readable signal.
When its all air it will put out "1% flex fault"
If i force the gasoline to mix with the alcohol by constantly shaking the jar where the pump is pumping i get a good reading.y
So i need to get an alcohol that can mix with gasoline.
nathaninwa
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Re: Continental Flex fuel sensor

Post by nathaninwa »

What kind of alchohol are you using? Is there more than just ethanol and methanol?
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Raymond_B
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Re: Continental Flex fuel sensor

Post by Raymond_B »

What Nathan said, any why not just go purchase some E85 or something? If it's not available then why use a flex fuel sensor :)
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jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

There is no e85 in my country, and since the sensor is an alcohol content sensor i supposed it would be able to sense isopropil alcohol in this case and it actually does but only when its mixed with gasoline and is stirred (forced to be mixed). If its pure alcohol it wont sense it, and i have actually seen a vid on youtube about a guy having pure e100 i a barrell and the same sensor not picking up any ie 0%

The rally evos here are using a 95+alcohol blend but i have yet to know what alcohol they are using that can blend. Toluene i know does but is also hard to get because of antidrug policies here.
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

Turns out the alcohol i tested was at 70% purity
I just tested isopropyl and ethyl 96% and both mixed ok with avgas... im letting them rest to see if by tomorrow there is a separation.
nathaninwa
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Re: Continental Flex fuel sensor

Post by nathaninwa »

You should watch this video. I test all my fuel now manually. I googled the difference between ethanol and iso, come to find out it is ethanol with water and other stuff mixed in. I would not trust the flex sensor for use with anything other than actual E98

(Mods, link is for information only, sorry it's from another company)

https://youtu.be/XEPJo1FN32k
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acedeuce802
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Re: Continental Flex fuel sensor

Post by acedeuce802 »

Unrelated to Megasquirt, but you want some sort of locking on the hose. Such as this connector: https://www.summitracing.com/parts/rnb- ... /overview/
elaw
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Re: Continental Flex fuel sensor

Post by elaw »

jasaircraft wrote:Turns out the alcohol i tested was at 70% purity
Yikes... throw that stuff out! The other 30% is probably water which of course is the last thing you want in your fuel.
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jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

thanks for the tips guys, yes that 30% is water but i only made it flow through the sensor and an external pump.

Turns out you cant read 100%ethanol btw... there has to be a different fuel for the sensor to be able to sense... in one of those vids on youtube a guy tested 100%ethanol and it read 0%.
it seems water contamination can also increase the reading a lot.

The sensor will use those hoses with clamps so no leaks can appear.

None of the tested alcohol (iso or eth) separated from the avgas now on day 2.
We tested ethyl mixed with avgas at around 50-50 and the gauge showed 47% so it seems very accurate.

The next problem I had is that flex fault label shows up all of the time for some reason i dont understand (the fuel rail and tank or lines having avgas only in them)
I "fixed" that by setting 49hz as 0% (50hz would give flex fault).
jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

Any ideas why 50hz throws the fault?

Also, when using the basic blend setup, how do I set the increase in boost at 100%ethanol?
Seem i have to enable blend curve6 on the boost table switch, which i did and i ended up with a lower boost that what the duty1 table gives me even though duty2 table was exactly the same.
slow_hemi6
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Re: Continental Flex fuel sensor

Post by slow_hemi6 »

It is probably set to raise the fault when the frequency is out of range. It Seems this is one of those times when 0% (50hz) is not out of range and you could say at some point should be expected. Probably just not enough leeway in the fault trigger point. If setting 0% @ 49hz fixes it I would say that that probably proves the point that the trigger is just a little too close, maybe it is 1hz under the 0% set point that raises the fault?
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jasaircraft
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Re: Continental Flex fuel sensor

Post by jasaircraft »

im on another car this time with the bigger square type of continental flex fuel sensors and input on ms3x flex in.
no problem with the default flex fuel setting throwing flex fault codes :?:
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