98 to 99+ fuel tables to get fuel gauge to read correctly

[fst100]

file attached now.

[laghinrat]

where is your file?

[fst100]

just attached it in my OP

[Holger]

I been reserching and doing some testing with this as well. I have a ECU from 2002 in a 1999 S10.
How did you come up with the -10 value? I haven't found any stock bins using a negative value, only positive.

And what does the "Primary Volume" really do? Because what i have found so far is that it doesnt do anything to the gauge.

[fst100]

i didnt, but others did holger. its basically that the 98s numbers are just flipped/inverted from the 99+

[laghinrat]

fst100 did you get gauge to work?

[Holger]

I can confirm it works great. Inverting the table does the trick.
I still have some dialing in to do on my truck tho. The gauge works, but im not sure how accurate it is yet.

[laghinrat]

mine seems to be real close....

[fst100]

i think when i used the -10 the first time it read correctly but for some odd reason i changed it to someone else's file which started with -11.99 and that was giving me inaccurate fuel level. im about to do another flash with the -10 at the zero value again and see if the needle reads differently. currently it reads in between quarter and half. if the -10 at the zero column is the correct one, then the needle should be reading lower/closer to the 1/4 marker.

[laghinrat]

the one i gave you started with -11.99

[laghinrat]

i would think you need to change your value in the are you think is not accurate....-11.99 is going to be empty by pwm.....if you think the 1/4 tank area is wrong then change the 20% area

[fst100]

ok i just did the reflash. before i did the flash, the needle was just a bit below 1/4 and after the flash its a bit above the empty. so you're saying -11.99 is correct?

[fst100]

i also noticed the file you have your fuel capacity is 16.6. did you swap over to the plastic 99+ fuel tank?

[LSxpwrdZ]

The proper way to calibrate the fuel tank takes ALOT of flashing and logging while at a gas pump....

How does the fuel gauge work?

The primary volume in gallons is the level used to calculate the percentage of fuel remaining. The sending unit outputs a signal to the PCM which looks up on the primary volume table to see current amount of fuel vs the primary tank volume. So if you have 16 gallon tank and have 8 gallons the fuel gauge "should" read half of a tank or 50%. This percentage is then used to lookup on the gauge output to send a signal to the cluster. So to get a fuel gauge to read correctly you need to calibrate both the gauge output vs percentage and the primary fuel level vs sender table.

I normally find the minimum gauge setting, half gauge setting and full gauge setting by entering the same value into the entire gauge output table and flashing the PCM. You will have to try various values to see where it puts the gauge on the dash. Filling the entire table with one value takes the primary fuel level out of the equation because now if its 100% full or 0% empty the PCM is going to output a set signal based off the gauge output table. Once you have plotted your fuel gauge output with various values between empty full and halfway you need to go onto the the primary fuel volume table. The easiest way to do this is to interpolate from 0 to 100 gallons on the other end of the table, flash it and start pumping gas 1 gallon at a time from empty. What this does is gives you a reference point on the fuel level table to show what the PCM sees when the tank is empty, 1 gallon, 2 gallon, etc. When logging the primary fuel volume you will need to cycle the key between 1 gallon entervals due to the averaging that gets done over time. This way when you turn the key on it starts averaging the current level and not previous levels while filling. Plot out the settings out by gallons and once you are done you can input those gallon values into the table and you will now have a properly calibrated fuel gauge.