Average MPG Malfunction
Thread Starter
Pro
Joined: Apr 2001
Posts: 663
Likes: 0
From: Omaha, Ne GO BIG RED
Average MPG Malfunction
Getting around to fixing all the little problems now that the big ones are done, had a question about the average MPG radout on the digital display. When I am at a stoplight, it reads 0.0 As I leave, it goes to 12.8, then 25.6, then 52 and goes between those numbers. Every once and a while it actually reads a good number, like 18.1, 18.2, 18.3 etc, but for the majority of the time it reads the 12.8, 25.6 and 52. Being a math person it seems a little linear to me. What controls this readout and what is the most likely cause for it's discrepency? I'd assume ECM, but looking for help first.
Thanks in advance
[Modified by 86Coupe, 7:43 AM 6/25/2003]
Thanks in advance
[Modified by 86Coupe, 7:43 AM 6/25/2003]
Advanced
Joined: Jun 2003
Posts: 54
Likes: 0
From: ST Inigoes MD
Re: Average MPG Malfunction (86Coupe)
sounds like it is set for instant average if it goes to zero when not moveing if you hit the botton one more time it should show over all average thats how my 91 works anyway I dont know about 86
[Modified by Phil stock 91, 2:46 PM 6/25/2003]
[Modified by Phil stock 91, 2:46 PM 6/25/2003]
Thread Starter
Pro
Joined: Apr 2001
Posts: 663
Likes: 0
From: Omaha, Ne GO BIG RED
Re: Average MPG Malfunction (Phil stock 91)
on my '86 the switch next to the info center can switch you between instant/off/average, the instant goes to 0 when stopped as well, and also show eradict numbers when in motion. But the display mentioned in the first post is when the switch is on average. Pretty sure it's an ECM or a sensor that causes it, hoping someone else has had the same problem and remedied it :)
Thanks again :)
Thanks again :)
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Average MPG Malfunction (86Coupe)
MPG is from the serial data line of the ECM and when erratic, usually the ECM is bad. Yours though sounds like a problem with the function switch. Switch Assembly is replaced as a unit. I don't know if it's available.
