DIC calibration

Does anybody know if the GM garages can calibrate the MPG readings on the DIC. Mine shows 20.4 and I'm averaging 18 MPG whem I check it manually after a fill-up. The 20.4 makes me feel good with the gas prices going up but, wish it was actually getting that.

dmince

Wow, wish my reading would say such to make me feel good! :) I'm avg'ing 15...sigh***

Does anybody know if the GM garages can calibrate the MPG readings on the DIC.
You can reset the milage setting by holding down the return key (the key on the bottom right that looks like an arrow). It will reset it to zero and start calculating from that point. It will never be 100% accurate, because it doesn't actually measure how much gas is used, it calculates it based on a special formula (don't ask me what it is).

Ummm.....that resets the mileage counter. I think the problem dmince is experiencing is more due to having the cluster programmed for the correct truck configuration. The "special formula" it uses is pretty simple. In the PCM there are contsants for the size of the fuel injectors. The PCM transmits this data, along with the "on" time commanded to the cluster, which then calculates the fuel used. It takes this data and accumlates it from the last reset (for the avg economy) then divides it by the accumated mileage to calculate the MPG, or GPM, or LPK. It's pretty simple, but the cluster needs to know the gear ratio of the truck, the engine, etc.... My guess is that the MPH is off on the replacement tach as well....and probably reads high.

I don't know if the tach was ever replaced. It has 3.42 gears and at 73mph the tach reads 2k. Are you saying the tech will need to fool the computer to get it more acurate? And it can be recalibrated?

dmince
'02 TB LTZ