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Have 2 fuel tables. How to tell which when each one is active..any idea why?


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Hi guys. 

Ive just bought a car that has a link extreme g4+ on it. Im trying to do a bit of fine tuning on the fuel map, as it runs very rich.  Im familar with megasquirt, as i have 2 cars running on that very well. 

It seems i have 2 fuel tables in the G4+ . What would the point of useing 2 fuel tables be? (They are both different btw) 

Where in the software does it tell the ecu which fuel table to run?...or is it running both at the same time??

Under parameters list, if i log it says fuel table 2 is active....but fuel table one says anywhere between 69 and 45%.

Is this normal?  

Thanks for the help. 

This is on a supercharged 1996 Dodge Viper GTS.



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  • Dunebuggyjay changed the title to Have 2 fuel tables. How to tell which when each one is active..any why?
  • Dunebuggyjay changed the title to Have 2 fuel tables. How to tell which when each one is active..any idea why?

Thank you.

Its set to interpolate between both tables. 

What would be the correct way to tune this? If its using both fuel maps, and interpolating between them both depending on ethanol content (looks like there is an ethanol sensor somewhere on this car,as i see a digital input for one (ethanol sensor) in the Link for it) ..what would be the correct way to adjust both fuel tables. Table 1 is not say 10 percent diff than table 2.  Each fuel cell is off by a different percentage from table 1 to table 2. 


Was hoping I could easily just fine tune the fuel map using mixture map.

But now with 2 fuel tables, and the car running a percentage of one and another, not sure its going to work that easy for me. 


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10 minutes ago, dx4picco said:

post your calibration file

See attached.


Note, I have turned off accel enrichment, and closed loop correction to try and dial in the fuel map table (when i thought there was just one)


I looked at one of my pc log files, and ethanol sensor is coming up as an error.


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As per dx4picco's comment, it looks like the ecu had been set-up for flex fuel at some time in the past but now has no flex sensor assigned/connected so it has defaulted to the sensor fault value which is set at 0% ethanol - so it is effectively running on fuel table 1 and ignition table 1 only.  

If you are going to run just 1 fuel you can turn off the dual fuel table and dual ignition table to simplify things.  If you want to run flex fuel then you would need to reconnect/assign a flex sensor and the typical tuning process is to drain the tank, fill with pure petrol, tune fuel table 1, then drain, fill with ethanol or E85 and tune fuel table 2.

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Thanks for the help guys. 

This car does have water/meth injection...that was turned on and off originally via a VEC 1 or 2...not sure which) . The last owner had the VEC removed, and this Link Extreme put in. So im wondering if the water/meth is even doing anything on the car anymore. Was thinking maybe that was why there are 2 maps. but if there is nothing triggering the water/meth injection...then who knows.







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33 minutes ago, dx4picco said:



furthermore, your ignition table1 seems a bit wierd.

Yes agreed. Not really sure whats up with the high load timing. The car does have a 10psi supercharger pulley...and if there is no meth turned on, maybe they are trying to keep the engine from knocking or blowing apart. The table 2 timing looked slightly better if i remember correctly. (Not at computer at the moment) 

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