mpg readout on instrument panel????
Thread Starter
Racer
Joined: May 2000
Posts: 429
Likes: 0
From: chagrin falls,oh,usa
mpg readout on instrument panel????
this is a strange one....
while out this evening, i noticed that the average mph has locked on 99 mpg!
i guess i'll try to do a reset to clear it, but i'm curious if anyone has had this happen or what the cause of it is????
thanks for everyones help! its much appreciated.
while out this evening, i noticed that the average mph has locked on 99 mpg!
i guess i'll try to do a reset to clear it, but i'm curious if anyone has had this happen or what the cause of it is????
thanks for everyones help! its much appreciated.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: mpg readout on instrument panel???? (johndezman)
My instentaneous has gone into the 80s on a down hill run but the average is usually fairly reasonable, interesting to see if it resets.
Le Mans Master
Joined: Jul 1999
Posts: 7,072
Likes: 4
From: Maryland
Re: mpg readout on instrument panel???? (scorp508)
I've had mine lock on 99, and lock on 0 before. A reset fixes it. :)
Burning Brakes
Joined: Sep 1999
Posts: 786
Likes: 31
Cruise-In II Veteran
Re: mpg readout on instrument panel???? (johndezman)
As info the MPG readouts are determined by the fuel injector constants.
If you start to see abnormally high MPG readings (especially the "instant MPG") this is a sign of possible fuel injector failure. As the injector(s) go bad and start dumping fuel into the engine resulting in a rich mixture, the computer adjusts the injector on-time (constant) to lean the fuel/air mixture to the proper ratio. The computer then interprets this adjustment in the constant to mean less total fuel is being flowed resulting in an incorrect MPG reading.
Been there and done that! :(
[Modified by Wildride, 8:22 AM 1/17/2002]
[Modified by Wildride, 8:25 AM 1/17/2002]
If you start to see abnormally high MPG readings (especially the "instant MPG") this is a sign of possible fuel injector failure. As the injector(s) go bad and start dumping fuel into the engine resulting in a rich mixture, the computer adjusts the injector on-time (constant) to lean the fuel/air mixture to the proper ratio. The computer then interprets this adjustment in the constant to mean less total fuel is being flowed resulting in an incorrect MPG reading.
Been there and done that! :(
[Modified by Wildride, 8:22 AM 1/17/2002]
[Modified by Wildride, 8:25 AM 1/17/2002]
Drifting
Joined: May 2001
Posts: 1,630
Likes: 0
From: Brandywine, Chester and Ridley Valleys Pennsylvania
Re: mpg readout on instrument panel???? (johndezman)
Nope, the problem lies between the dash and the ECM. I recently replaced the ECM, as before for two to three years the "MPG" readout would either "freeze" on 0 or 99 at startup or it would work for a brief period and freeze on whatever MPG it happened to be displaying when the problem occured.
Now, the "MPG" usually works. I say usually, because there are times when it "freezes" on a number or is frozen on 0 at startup. But it's much more uncommon than before. And there's a completely different set of factors that lead up to a "MPG freeze".
I say all this because I think I had a couple of problems going on between the dash and the ECM, and the new ECM cured the faults which the old ECM was responsible for. Now I'm thinking either the wiring or the dash itself are to blame for the remaining gremlins.
Now, the "MPG" usually works. I say usually, because there are times when it "freezes" on a number or is frozen on 0 at startup. But it's much more uncommon than before. And there's a completely different set of factors that lead up to a "MPG freeze".
I say all this because I think I had a couple of problems going on between the dash and the ECM, and the new ECM cured the faults which the old ECM was responsible for. Now I'm thinking either the wiring or the dash itself are to blame for the remaining gremlins.
Thread Starter
Racer
Joined: May 2000
Posts: 429
Likes: 0
From: chagrin falls,oh,usa
Re: mpg readout on instrument panel???? (TrueBlue ChevyDude)
this is the first occurrence so i'll try to reset it and see what happens.
by the way, did you have any operational issues (or more correctly what were they)?
seems this started within the last week since i installed a msd 6a. i don't think there should have been a connection but it sure is coincidental!
the msd saga ...
installed the 6a per the instructions, used the tach feed from the side of the box and the tach worked fine. however it set a code 42 which is an open or short in the esc. called msd, they recommended installing the #8910 tach filter did that and no change yet. called msd back and they haven't returned my call yet (since last thursday) since then i've gotten the new design esc module from jeff at superior chevy and that seems to have gotten the the performance back but the code won't clear. still waiting on msd..........
by the way, did you have any operational issues (or more correctly what were they)?
seems this started within the last week since i installed a msd 6a. i don't think there should have been a connection but it sure is coincidental!
the msd saga ...
installed the 6a per the instructions, used the tach feed from the side of the box and the tach worked fine. however it set a code 42 which is an open or short in the esc. called msd, they recommended installing the #8910 tach filter did that and no change yet. called msd back and they haven't returned my call yet (since last thursday) since then i've gotten the new design esc module from jeff at superior chevy and that seems to have gotten the the performance back but the code won't clear. still waiting on msd..........
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