[Marc Roberts]

I recent drove a ten mile trip and experienced a false reading on the mpg display. It read only zero or 150mpg, nothing in between. The problem did not appear on the next or any subsequent trip since. Does anyone have any ideas on what caused this?

 

[Rick Reece]

Marc,

Others have reported this occasionally. Seams to be a software glitch that some say is because they started the car too fast. I don't think anyone has had it happen more than twice and most have never seen it. Anyway I doubt the car was actually getting 150 mpg so depending on how long it took to clear I would go with the gas guage for fillup vice the trusty FCD this time. Have fun, Rick

 

[bfivelover]

I was going to post the very same thing as it happened to me on the way home from work today. This happened stopping at a red light and auto-stop didn't engage. I turned the ignition off and restarted when the light turned green. It stayed at 150 and didn't move until I stopped, turned the engine off, and restarted. It was fine the last 20 minutes going home.

 

[Insightful Trekker]

Its a "glitch" in the MPG "computer" I've seen it 3 times in my 02. Simply takes a "reboot" to fix. Key off, wait 3 seconds, restart.

Or go for broke and leave Rick Reece's MPG record in the dust :!: :twisted:

 

[Rick]

This has come up several times, but in some 40K miles I've never ever had this happen. Wounder if it's some specific sequence done at start up that no one realizes they're doing.

 

[Aaron Cake]

Happens to me everytime I run out of gas. The next start and short trip afterwards will always show this behaviour. Only seems to be present in the new software, since pre-ECM replacement I never observed it.

 

[bfivelover]

Wonder if it's some specific sequence done at start up that no one realizes they're doing.

It happened again yesterday just after leaving work, second day in a row. I stopped at a red light, and since the engine wasn't warmed up enough to auto-stop, I turned the key to"Accessory" or "On"(not sure which) just as I had done the day before to turn the engine off. After restarting, it went to 150mpg and stayed there till another red light when auto-stop engaged and the graph went to "0". After the red light, the graph didn't move, but the MPG continued to rise as if the graph were at 150. At the next red light, I turned the ignition completely off and restarted which fixed the problem. These were the first two times this has ever happened to the car. I have never really turned the engine off at red lights before until recently, so it must have something to do with that.

 

[kNOwtalent]

I recent drove a ten mile trip and experienced a false reading on the mpg display. It read only zero or 150mpg, nothing in between. The problem did not appear on the next or any subsequent trip since. Does anyone have any ideas on what caused this?

Greetings Marc,
It happened to me today I didnt notice it till I had gone some distance, 15mi or so, as the area was somewhat hilly and I was in traffic I wasnt paying that much attention to my FCD. It was only when I saw my assist at half and the FCD that I processed what had happend

 

[freezin4]

False sMPG and Bar Graph Reading

Resurrecting an old issue which is new to me. A glitch in the MPG calculation after you do a FAS. The Bar Graph was moving between zero and 150. Zero at stops and 150 when car in motion.

I was excited for a while until I figured out it wasn't for real.
But I got a cool screen saver for my phone now.

 

[diamondlarry]

I've had it happen a dozen or so times and it was always after using the ignition to do a FAS. Since I've installed my injector interrupt switch to initiate a FAS, I haven't had it happen again.

freezin4, I've had a couple of times that I had the FCD maxed out for about 15 miles or so and it was actual; I had to switch to metric to see what I got on those trips. One of them was 1.2L/100km.

 

[weelliott]

I figured I'd interject my two cents in case it might give curious people some knowledge to figure out why this happens.

In my case, I'd had the CEL come on about 10 days prior, and had checked those as the 0420 and 1420 codes. I'd intended to go to the dealer and have the 07-036 TSB software update performed, but never got around to it.

So as I'm driving to work yesterday I get the eratic behavior, which at first I thought was awesome mileage, until I started climbing a hill at 35 and it was still at 150 mpg. Upon stopping at a light it went to zero, and wouldn't budge from zero until I got up to speed, at which time it went to 150. The IMA still seemed to be working correctly, so I didn't worry too much. About ten minutes of this went on until I forgot to turn off climate control coming up to a stop light so the car didn't auto stop. So I wound up shutting off the ignition and restarting the engine once the light turned green. Upon restarting, the bar graph started working correctly again, and the CEL was gone.

It might be coincidental. It might not be. Is it possible that every once in a while the software recalibrates or reboots, and while it is doing so the first start-up has wonky mpg numbers? I can't say I'm all that vested in figuring out the why of the phenomenon since it doesn't seem to be detrimental to the car, but figured I'd throw my piece of data into the mix if others care to mull over it.