[LeeTaylor]

I have a flex sensor and running E85 all works well have my flex corrections and VE dialled in, but at full throttle the ethanol percentage likes to jump to ~100%.

I'm currently running ~88% ethanol in the tank, notice this log screenshot where TPS @ 100% the ethanol percentage jumps from 88 to 99% which adds more Flex enrichment.
I also noticed the fuel temperature sometimes randomly jumps to very high or low temperatures for less than a second.

I have tried playing with the flex filter in tunerstudio, the recommended says 75, I have it at 150 and have tried all the way up to the maximum but too high and its too slow to react, I tried high filtering but after starting the engine it runs lean for a few seconds as the ethanol percentage slowly creeps up to the correct ethanol content.

Is this a noisy signal? I have the flex sensor powered from the same 12V positive & ground as the Speeduino.

I am running it in the feed line as there is no return line in this factory Toyota fuel system, I understand most run in the return line, but I know a lot of people will run it on the pressure feed line with no issues as long as it isn't a restriction, this won't be a restriction as its only factory making less than 100hp.

Can I place a resistor or capacitor of some sort in the flex sensor circuit without interfering with the signal it outputs?

[PSIG]

There is a lot of info and data we cannot see with a screen shot. Please post the tune used and a good log of the issue as a pair. Combined in a ZIP file is a good way to do it. Pairs (tune & log taken with that tune) ensure we are seeing the specific settings and logged effects together.

If you have oscilloscope data of your sensor's electrical and signal, also include those.

[LeeTaylor]

I've attached a short log of a 2nd and 3rd gear pull, and the tune file. I did notice after just installing a pressure sensor I lose a few PSI fuel pressure, but as you can see from the log even 5th gear full throttle towards the end when pressure is stable the fuel temperature is all over the place.

BTW is currently naturally aspirated, will be turbo hence the unused rows on the VE tables . Trying to work out these issues before I start adding boost to the equation

[PSIG]

I would first turn all Local Aux channels OFF. Then load Calculations.dash in TS to see why GammaE is pushing oddly and affecting PW, DC and resulting O2 when Eth% is relatively stable. I would 'scope the flex sensor signals to know what Speeduino is supposed to be reading. I can't tell from here if it's a bad signal or a confused ECM.

[LeeTaylor]

Thanks so much for your input, I will be sure to try that, I didn't even think of using the calculation dash. I'm new I don't even use the Aux Channels anyway, if I set the secondary serial off it will achieve the same thing, yes?

I have a scope on the way as it's a handy addition to the toolbox anyway

I'll let you know how I go

[LPG2CV]

Be aware that flex is pwm, and the signal contains both E content and fuel temp.

[jonbill]

which speeduino version? if its recent, perhaps its possible the demux of the two values got broken by a PR

[LeeTaylor]

which speeduino version? if its recent, perhaps its possible the demux of the two values got broken by a PR

It's a new "Everything Fuel Injection" basic unit with version 2022.07 on it

[jonbill]

it's quite a lot of work, but it might be worth trying an older version. go back a year or so 1 e. g. 202103.

[LeeTaylor]

Update on this issue!

I was having random missed syncs once or twice in 45 minutes of driving. I was running only the crank sensor with it in batch and wasted mode, and cam sensor disconnected, but eliminated the shared ground in case there was something weird with the shared ground and the shielding even with the sensor disconnected.

Zero sync issues now FIXED!

Flex signal was still noisy and bounced around fuel temp up to 125 deg C and down to -40 randomly, and ethanol content would jump around and then increase under throttle until it maxed out.

Changed all my grounds to run separately all to the cylinder head, main ground to the same point, grounded the flex sensor to the same point. Star point grounded everything. Still noisy signal.

Then this afternoon had a random thought about a 1JZ I had 5 years ago with these "Yaris" coils that are standard on this Toyota Echo, but are used as an upgrade for big horsepower builds.

Everything online showing pinouts of the Toyota COP's suggests the IGF ignition feedback wire that sends a signal back to the factory Toyota ECU to confirm the coil has fired, is not needed. I had noise on my 1JZ with these coils at 16psi of boost causing misfiring. Against everyones advice online saying the feedback pin was not needed, I was told by Wolf EMS whose ECU I was using that it needed to be grounded on each coil. As soon as I did that all the issues went away and made 32psi and 530hp on E85 for a few years. Haven't ever seen anyone else ground the IGF pin, everyone says it isn't used.

I didn't have the feedback pins connected to anything as I was running off the factory loom with a patch loom I made and left the IGF pins disconnected without realizing. I grounded the feedback pins from each coil to the cylinder head and WIN WIN! No more noise!

Flex sensor works perfectly now ethanol percentage and temperature is spot on!

Noisy coils was the issue the whole time!

This is the pinout everyone gives for these Toyota NZ / Yaris coils. The IGF needs to be grounded when not used with the OEM Toyota ECU. The car will run, but you'll be generating stupid amounts of electrical noise.

Hopefully this info helps someone else some day