Instantaneous and Average MPG Reading Not Working?
Thread Starter
Heel & Toe
Joined: Aug 2001
Posts: 22
Likes: 0
From: Hawthorne CA
Instantaneous and Average MPG Reading Not Working?
'89 vett with 72k miles
My final - always final problem - is the average and instant mpg reads 0 or 99 - sometimes just random number that respond or not respond to the actual driving - it used to work somewhat intermittently.
All other readouts are seemingly correct except miles remaining - which I would guess it using the average mpg.
is there any sensor or other item I could check to troubleshoot this?
thanks,
barrypaul
[Modified by barrypaul, 1:41 AM 8/8/2002]
My final - always final problem - is the average and instant mpg reads 0 or 99 - sometimes just random number that respond or not respond to the actual driving - it used to work somewhat intermittently.
All other readouts are seemingly correct except miles remaining - which I would guess it using the average mpg.
is there any sensor or other item I could check to troubleshoot this?
thanks,
barrypaul
[Modified by barrypaul, 1:41 AM 8/8/2002]
Drifting
Joined: Dec 1999
Posts: 1,319
Likes: 2
From: Douglasville GA
Re: Instantaneous and Average MPG Reading Not Working? (barrypaul)
Would you by chance happen to be running some sort of ECM diagnostic scanner when the failure occurs? The features you mention are affected by Diacom and AutoXray...
Tom Melton
82 CE
86 Z51 Coupe
Tom Melton
82 CE
86 Z51 Coupe
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Instantaneous and Average MPG Reading Not Working? (gbody5)
Mine does that too.. but it's because i have 30# injectors in .. it has no idea how much gas i'm throwing in the cylinders, lol. :D
Guest
Posts: n/a
Re: Instantaneous and Average MPG Reading Not Working? (gbody5)
Have to agree with gbody5, the 2 items are the only display parameters supplied by the ECM. If you haven't changed ECM's leading up to this problem, it's either a loss of communication between dash and ECM or bad ECM. The calculations for these items is based on time and tank level so the only sensor involved is tank level. HTH
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Would you by chance happen to be running some sort of ECM diagnostic scanner when the failure occurs? The features you mention are affected by Diacom and AutoXray...
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Re: (scorp508)
The fuel readouts use injector on time in computing fuel efficiency, along with the distance computation, not fuel tank level. This can be noted when people install larger injectors and may see fuel mileage readouts going from say 25 to say 27 mpg. The larger injectors have less ON time and the ECM uses this on time to determine fuel flow but is using the stock injector flow rates. The ECM uses the flow rate with the distance traveled over time to determine mpg. Those engineers are so clever.
dlmeyers 90 coupe zf6 3 speed shocks
dlmeyers 90 coupe zf6 3 speed shocks
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
This can be noted when people install larger injectors and may see fuel mileage readouts going from say 25 to say 27 mpg.
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