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Delay on flex fuel sensor


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I'm running a g4+ plug in with my jza80 and on start up I'm getting a 4second delay on my flex sensor. It's gm sensor and I also have a gauge taped into the wire from my sensor to the di pin which Is for a brake light switch that isn't used in the factory loom.

my tuner is pretty stumped on this issue and I'm a bit concerned that he has not figured it out because it really effects my start up. 

Any help on the issue would be great thanks.

here is a link to the gauge and sensor I'm using.




Edited by Martyjet
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I would adjust the fuel pump prime time to be maybe 10 seconds.

Then adjust ethanol sensor lock out to be 5 seconds.

when starting car:

first put the key on,

Then count to 5 for the ethanol sensor to go live.

Then start the car before the fuel pump prime time ends.


ethanol sensor lock out time.png

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Thanks for your reply mate

but that's kinda giving me the same problem 

is there any way I can set it up so I can start the car without waiting for 4/5 seconds for everything to register? 

My mate has a thunder and the same flex set up and he does not have the delay 



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I'm having trouble understanding what problem the sensor start up delay is causing you?  During the "lockout time", the ECU will use the last ethanol content value that was measured before you last shut the engine down.  So unless you have significantly changed the fuel in the tank since the last start up then it shouldn't matter if the sensor takes a few seconds to start giving an accurate reading - the ECU will be using a ethanol % that is reasonably valid and will allow the engine to start up and run well.

You can set the sensor lockout time to zero if you don't wish to have a delay but then the ECU will start using the value that the sensor is outpuitng right away which is likely to be less valid as the suggested setup as air bubbles etc first pass through the sensor. 

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Also mate, thanks for your reply.

im just going off what my tuner is telling me. I'm not a tuner by a long shot.

he is saying on start up the car won't start first go because it has a 4 second delay to register what fuel is in the sensor??

when you first start the car it revs then stalls. Then on the second start it will start. 

is that normal?

before when I was running just pure 98 the car would start first kick. 


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he is saying on start up the car won't start first go because it has a 4 second delay to register what fuel is in the sensor??

No I think he is probably mistaken here.  The ECU should have a realistic ethanol content value stored in its memory to use for start up.

Your symptoms sound more like the idle valve set up or pre-crank and post start fuel tuning related.

Also keep in mind most engines are a more difficult to cold start on Ethanol based fuels as they are less volatile.  This effect gets more worse as temperatures drop so even when all settings are optimised/tuned correctly you will likely never see as good start up behavior as petrol.

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