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Discussion Starter #1
Just curious if anybody else has experienced this problem or if there is something I'm missing regarding the flex fuel sensor.

I'm using a brand new GM/Continental 13577379 flex fuel sensor on a Motec M1 system. I installed it today and found that it's reading 72hz exposed to air, and 84hz with premium gas. This sensor is supposed to be a 50-150hz setup and it's claiming my pump gas has 33% ethanol. It's all wired as it's supposed to with a 12volt source, ground and an input sensor. The motec seems to read it just fine, but the readings are abnormally high.

As a test, I put some e85 in it and it read 150hz or 100% ethanol.

So question is has anybody experience issues with these being bad and if so is this something they do? I googled and only found one other issue on the miata forum of someone having a similar issue of reading high, but there was no resolution to the thread.

any input would be helpful :)
 

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Good catch, I never ran my car on ethanol yet but made sure my identical flex sensor came in around 9% as 93 gas in my area is E10.
 

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Discussion Starter #7
Got another new one and having the same issue. Now not sure whats up.

We tested the first one on a proefi car with a working sensor and it read 22% on that car exposed to air. Exact same as it read on my motec

Put new sensor in today and got 30% ethenal again :(. Not sure what to do now.
 

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What are your settings? Mine works just fine with my M1.

You can send me your file if you want to compare... PM for email

DP
 

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Discussion Starter #9
What are your settings? Mine works just fine with my M1.

You can send me your file if you want to compare... PM for email

DP
John reed has the car now. Here is how I had it setup:



The strange thing is we plugged the first sensor into a friends car with Pro EFI and the same model sensor. His sensor on his system measured properly and then when we plugged mine into his it registered the same that it was reading on the motec. That's what made me believe it was a sensor issue, and why I got a second sensor.
 

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John reed has the car now. Here is how I had it setup:



The strange thing is we plugged the first sensor into a friends car with Pro EFI and the same model sensor. His sensor on his system measured properly and then when we plugged mine into his it registered the same that it was reading on the motec. That's what made me believe it was a sensor issue, and why I got a second sensor.
So John is dealing with it now?

If that is the case he will most likely find the issue.

DP
 

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Discussion Starter #13
Update from John Reed on the flex fuel sensors. Both are bad. One was purchased from GMPartsdirect and was in OEM GM packaging, and the other was purchased from amazon. Had to pull the sensor out of his rally car to get it to work, which also was the same model sensor.

Pretty crazy I got two with the exact same issue. Wonder if it's a manufacturing defect that will be more common here in new sensors.
 

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Update from John Reed on the flex fuel sensors. Both are bad. One was purchased from GMPartsdirect and was in OEM GM packaging, and the other was purchased from amazon. Had to pull the sensor out of his rally car to get it to work, which also was the same model sensor.

Pretty crazy I got two with the exact same issue. Wonder if it's a manufacturing defect that will be more common here in new sensors.
Had the same issue, also from gmpartsdirect. Builder swapped in a known good sensor.
 

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Just to add to the list, I am having the exact same problem as the OP. I tested my sensor in open air and I am getting 72hz and 84hz with pump gas. I am ordering a 13577394 sensor, because the OP said that is the only thing that fixed the issue. He had 3 bad 13577379 sensors. I will post with my findings when I get my new sensor.
 

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I have the Continental 13577394 and it seems to work just fine. The only difference is that i used 5v reference from the Proefi and sensor ground to power this sensor.

It reads 9% on Pump gas which sounds right and E81 when i put Ignite E90 in the tank with a splash of pump left.

Now everywhere i read it seems that this sensor should have 12 v. Mine works just fine with 5v.

Ryan
 

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Discussion Starter #18
I should also add I bought a 3rd one and it also provided the same readings. I'm now on 13577394 version and it's working just fine.
 

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I have the Continental 13577394 and it seems to work just fine. The only difference is that i used 5v reference from the Proefi and sensor ground to power this sensor.

It reads 9% on Pump gas which sounds right and E81 when i put Ignite E90 in the tank with a splash of pump left.

Now everywhere i read it seems that this sensor should have 12 v. Mine works just fine with 5v.

Ryan
I changed the voltage to 12v and it is reading the same... So for reference, this sensor will work with 5v or 12v.
 

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It may work but using a 5V reference output for a component with unknown power consumption seems risky (so far I couldn't find any Continental datasheets online). I would not recommend that as it could damage the ECU hardware or shut down the flex sensor because of the low current limit of the output.
 
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