Im having 2 seperate issues... or maybe they are connected. Here they are:

1. I dont know how its possible, but i found a local BP that claimed they have premium. I idled and waited for 30 min before finally filling up. After i filled up and restarted, THE DISTANCE TO EMPTY READ 250 MILES!!!!!.... i normally get 340 -380 depending on whether i was driving on the streets or highway prior to filling up. I shrugged it off thinking all that idling before AND street driving for a week prolly killed my mpg.

I aways reset my average fuel economy after filling up, and i know it fluctuates wildly....my guess is that as soon as u reset, it averages for the immediate short distance. So its normal for me to see 10 mpg driving in the streets after reseting, or as high as upper 20 if im on a highway. Im not concerned about avg fuel eco.

http://s11.postimage.org/6j6ees4oz/2..._06_47_253.jpg (large image)


I am concerned about "fuel economy record" bar graph. I dont know if it auto resets when i reset avg fuel eco, but i knew from the past that while avg fuel economy could easily change high or low, fuel economy record is pretty much consistent and does not change easily.... like the mpg history in the center dash. I always get around 19-20 for the last 2 years. As you guys can see from the pic, u can clearly see what the "norm" is in the first half of the fuel economy...... and when it went to hell by seeing the huge drop after leaving the gas station, post hurricane Sandy fill up. I attempted to reset again, with same results. I drove for 50 miles across NYC today, and i reset avg fuel eco while i was on the highway and now fuel economy record is off the chart... wtf?!? RESETTING AVG FUEL ECO ON A HIGHWAY NEVER AFFECTED FUEL ECONOMY RECORD THIS MUCH IN THE PAST... I had my eye on the distance to empty, during the trip and it slowly crept up from 250 to 340. I saw the fuel gauge slowly drop while i was driving .... to me it felt like consumption increased, but i cant tell cause everything is so screwy. Whats with my fuel economy record???????

http://s12.postimage.org/5jv9akt4d/2..._06_54_124.jpg (large image)


2. What does an engine knock / ping feel and sound like? I heard a sound that i thought was a rock hitting the body of the car.... either on the roof or the hood. No signs of impact though. It was like a single loud ping or knock. I did not feel anything different with my car at all performance wise. I did not floor or accelerate rapidly, but i did drive 60-80. I have doubts about this supposed premium gas.

If this was a engine knock/ping.... does this mean my engine is already damaged??



Wtf is going on here????

 

For the fuel economy. The miles to empty is determined by recent driving activity and resetting the average mpg tracking doesn't affect it. So it saw the extended idling and changed accordingly. After driving around normally it should gradually get back to what it usually is. It works the same way going from all highway to city only. After a longer road trip, my miles to empty was showing over 500 miles, but gradually got back to my normal 375ish at the next fillup.

The average fuel economy shown in the 1st pic takes a few miles of driving to show up after being reset. If you have been all city, it will reflect that, close to 10-15 mpg, and high, 25 or more, if it was on the highway. As you drive more miles, it will start to move towards the 20 mpg you probably normally get if you drive a mix of city and highway.

The fuel economy record shows the last 10 (?) average fuel economy records. If you reset the average fuel economy, it stores what ever was shown before resetting to the record screen. Since you reset it a couple times with low mpg on the average fuel economy, they show up in the record. As for the latest reading, if you reset on the highway, it would explain the higher reading. If you want to clear the entire history, there is a way to do it, but can't remember off the top of my head.

Hopefully that makes sense. I wouldn't worry about the gas.

Engine knock isn't a one and done type thing. It will continually knock. Even with regular grade, the ecu will retard the timing of the engine to prevent knock and limit output even if you floor it. But driving normally on regular grade, you should never encounter knock.

So no, it isn't knock. It most likely was a rock chip or something that didn't cause any mark. And even if it was knock, a single isolated knock will not damage the engine. Only if it is allowed to continue for extended periods of time

 

Thanks for the explanation, it puts my mind at ease a little.

I still don't ever recollect the fuel economy report being that screwy in the past, even while resetting on the highway... but maybe I just remember it differently.

One thing though... does the avg fuel eco ever reset on it own after a while, or does it always have to be manually reset?

 

1) That definitely wasn't a pinging/knocking/detonation event.

2) I never use the whole fuel economy tracking info on the main screen; always seemed too much trouble to use and didn't seem particularly accurate. I stick with the simple trip computer in the speedo cluster. If you routinely do the resets, those readings are phenomenally accurate.

 

The only other factor for my gas reduction ...however trivial... is that this is also my very first fill up using the new WIX air filter...

 

Man, you're overthinking this . . . that air filter had nothing to do with it.

 

Lol ur prolly right.