Hello everyone! I got a 2004 HCH and am currently getting around 46.5 mpg. I have noted fluctuations in the mileage where it will go to as low as 40.

I know what everyone is going to say next: 'it's the way you are driving' . I can assure everyone my driving is the same.

I first noticed a change from around 47 mpg down to about 40 after adjusting the valves. I did rotate the crank with the engine off to do the adjustment.

The mpg stayed roughly around 43 -44 for a month or so then after a long trip (yes it was freeway) the mpg jumped to around 50 mpg and stayed like this for at least 2 tanks of fuel. On another recent trip I had a load of people and drove a mountainous route. The mpg dropped to its current state through 1 tank of gas.

My question is does the computer learn and try to adjust fuel consumption based on engine/motor load or driving conditions? It seems the my computer may be changing fuel consumption for some reason. I was thinking it needed to relearn the crank position or something like that since the the MPG dropped after valve adjust and crank movement with engine off.

Is there a way to reset the computer?

Thanks for looking!

 

Seems to be a connection that I have uncovered.

FYI

When I use Chevron unleded/super unleded my mileage jumps to around 50/mpg. If I use Arco, Shell, or Valero the mileage drops to 45 or below.

Haven't tested with Mobile yet.

So far my little car seems to really like Chevron for some reason....