evo 1-3 /gsr octane sensor

[khubner1]

so i was looking over the gsr ecu pinout diagrams the other day and noticed one labeled octane sensor. now the description was intank octane sensor for the emergency use of less then 98 ron fuel. and it got me thinking how hard/ easy would it be to change this sensor out for an eflex sensor for use with either a chiped or aftermarket ecu.

the sensor supposedly retards timing when lower quaility fuel is used to safely get you home. now obviously changing this sensor would be so that you could run pump available e85 which is never true e85. this would be handy istead of having to buy barreled e85 you could just use pump gas.

what are your thoughts on this. since the section of the forum has been alil quiet of late.

 

[JETGSR]

thomas is working on ECMlink so that interfaces with the GM flex sensor i think

my haltech can interface with them, which gives you 1 of 2 things

either run 2 maps on of lower ethanol rating and one at E85/E98 the sensor will measure the amount of E in it and intertopilate between the 2 maps
the only problem is E85 is very much temp related so tuning may be off.

the other is using the sensor as a trim which would either trim the fuel / ign or both not the best as you need to have your map checked at both extremes so that the triming is enough to make it safe.

 

[caged]

so i was looking over the gsr ecu pinout diagrams the other day and noticed one labeled octane sensor. now the description was intank octane sensor for the emergency use of less then 98 ron fuel. and it got me thinking how hard/ easy would it be to change this sensor out for an eflex sensor for use with either a chiped or aftermarket ecu.

the sensor supposedly retards timing when lower quaility fuel is used to safely get you home. now obviously changing this sensor would be so that you could run pump available e85 which is never true e85. this would be handy istead of having to buy barreled e85 you could just use pump gas.

what are your thoughts on this. since the section of the forum has been alil quiet of late.

Just tune on the caltex winter blend aprox E70 and tune slightly rich, that will cover all the caltex blends. You can still make great power on caltex fuel flex. Heaps of aftermarket ecu's can run fuel flex sensors, if you haven't seen the sensor before it taps into the fuel return and the fuel runs through it to calculate ethanol content.

 

[khubner1]

Oh I'm not planningon running or any time soon since none of my local stations stock it. Just trying to generate conversation.

 

[4piknup]

thomas is working on ECMlink so that interfaces with the GM flex sensor i think

ECM link has hi and low octane tables, but I have no idea how it chooses what octane the fuel is. Maybe it has something to do with knock or sone other sensor.
But, if it sender based you could have your e85 map on the high map utilizing bigg boost, then use the low octane map as a 95 Ron tune and switch the sender as well as the street boost setting on your boost controller??

 

[khubner1]

currently ecm link uses the octane sensor in the tank to switch the tune. problemb is with e85 flex fuell the octane is supposed to stay the same via adetives etc. just the amount of ethanol changes.

my thoughts were on using a proper flex sensor and using that octane sensors input for the flex sensor.

 

[brisvr4]

currently ecm link uses the octane sensor in the tank to switch the tune. problemb is with e85 flex fuell the octane is supposed to stay the same via adetives etc. just the amount of ethanol changes.

Where did you hear that rubbish?
If you don't know the correct answer please don't answer at all. It helps to stop misinformation getting out there!

This is a direct quote from Ecmlink's wiki page with the correct answer...

Effectively, the DSM ECU uses two tables to calculate a “basic” ignition advance value. One table is used when the ECU believes fuel octane is at its highest value. The other table is used when the ECU believes fuel octane is at its lowest value. The ECU interpolates between these two extremes by adjusting its idea of fuel octane. This adjustment is done by monitoring knock retard (the amount of ignition delay added in by the ECU in response to knock sensor activity). More detonation means more knock retard and a lower “value” for the ECU's fuel octane rating.

Octane “update” only happens if the following are all true.

Coolant temps are above around 180F
RPM is above about 2500
Airflow is above some threshold
The airflow threshold is actually a table lookup indexed by RPM. So it varies slightly, but basically you can think of it as only active while running with a decent bit of airflow (not cruising or idling).

Once those conditions are met, the ECU will look at knock retard and adjust the long term octane scaling according to the following rules:

Increase LTOctane by 1 if knock retard < 1° (raw knock “sum” of 3)
Decrease LTOctane by 1 if knock retard > 2° (raw knock “sum” of 5)
Between these two values, no update takes place
LTOctane has a scale of 0 to 255. A value of 0 means use the timing value retrieved from the “bad octane” table. A value of 255 means use the timing value retrieved from the “good octane” table. Values in between result in interpolation between these two extremes. At 128, for example, the timing value used will be the mid point between the “good” and “bad” octane table values.

The update is further gated by a timer that requires a certain amount of time to pass between updates. That time varies from 1G to 2G. For a 1G, it's a flat 0.4 seconds between updates. For a 2G, the ECU requires 1.2 seconds to pass after an increase in octane rating and 0.6 seconds after a decrease.

 

[4piknup]

so i was looking over the gsr ecu pinout diagrams the other day and noticed one labeled octane sensor. now the description was intank octane sensor for the emergency use of less then 98 ron fuel. and it got me thinking how hard/ easy would it be to change this sensor out for an eflex sensor for use with either a chiped or aftermarket ecu.

i dont see the octane sensor pin on our evo 1-3 ecu pinout drawing.
what pin is it?

 

[(2much)]

Need to read, people