2 problems with Scangauge II. Can you help?

[regor]

I have 3 scangauges, which are used on a:
08 Honda Civic
01 Chevy Silverado
99 Ford Contour

I have 2 problems and 1 problem deals with all 3 vehicles. They have the latest firmware.

Problem 1 (Impacts all three scangauges and vehicles): Almost every time, when I take the foot off the accelerator , the “MPG” guage under gauges will read “9999”. Only if I put my foot back on the accelerator will the gauge read normal. I’ve unplugged the cable on back and have also switched the scanguages-same problem.

Problem 2 (Impacts only the Silverado): While driving, the radio will turn itself off and reset to 1:00.

SO I’m open to fixes.

Yes, I have emailed Linear-Logic, Inc. about the problems.

[cfg83]

regor -

I suspect the 9999 is not a problem per se. When you take your foot off the accelerator, your cars cut off fuel to the injectors. In this situation you have "infinite MPG" :

MPH / GPH = MPG => 50 MPH / 0 GPH => Infinity MPG

The Scangauge's don't have a symbol for infinity, so they display the largest number on a 4 digit display, 9999.

This could also be an artifact of the algorithms. For instance, if I were programming the scangauge, I would be watchful for divide-by-zero errors as displayed above. In that situation, I would probably divide by a super-teeny constant, say 0.0000001 GPH, which would yield "infinite MPG" for practical purposes :

50 MPH / 0.0000001 GPH = 500,000,000 MPG (aka infinite for comparison purposes)

Since my above example can yield "different infinities", they probably compromise and just display 9999 in all cases.

I saw this exact-same behavior on a Renault Megane diesel in Europe. I don't have fuel cutoff in my Saturn. You should be happy!!!!!!

In terms of the second problem, that's really whacky!

CarloSW2

[Matt Herring]

when u take your foot off the gas pedal the engine continues to run and burn fuel so infinite mpg is not accurate. engine off coasting would be the only time infinite mpg is true. i do not have a scanguage but would like an accurate reading when my foot is off the gas too...good luck with the problem

[trebuchet03]

As already said

1st problem isn't a problem - when you aren't on the gas and in gear, engine management can cut fuel (maybe no completely, but as cfg said, potentially outside the SG's range). Many modern cars do this

As for the second...
Sounds like your radio has a problem o.0
a) does it happen when the SG isn't plugged in?
b) if no, did you try using the SG from another car in the silverado?
c) even if it only happens while the SG is plugged in, something tells me it's not the SG and a preexisting electrical problem (the SG is just making it evident).

[regor]

Radio works fine w/o scangauge. I've put the other scangauges and same issue. It's not the radio but some thing with the scangauge.

[trebuchet03]

Originally Posted by regor

Radio works fine w/o scangauge. I've put the other scangauges and same issue. It's not the radio but some thing with the scangauge.

Have you tried any other OBDII devices other than the SG?

So I take back what I said before.... It's not an electrical problem, it seems to be a programming problem with your Silverado's computer....

I found this thread, which may or may not be of use:

ScanGauge Troubleshooting - CleanMPG Forums

[cfg83]

trebuchet03 -

Originally Posted by trebuchet03

Have you tried any other OBDII devices other than the SG?

So I take back what I said before.... It's not an electrical problem, it seems to be a programming problem with your Silverado's computer....

I found this thread, which may or may not be of use:

ScanGauge Troubleshooting - CleanMPG Forums

That's a sticky whicket. Technically, the Silverado computer came first, so it's up to Scangauge to "work with it". But, it *could* be the Silverado's fault if it is grossly non-compliant with the OBD II spec. They must be doing some kind of "trick" to control the radio.

regor -

Is there something special about the behavior of the Silverado's radio? Does it do anything other than be a radio? What I mean is, does the Silverado use the radio display to "report" any special car information? If yes, then it is likely that there is custom programming between the radio and the car computer. A generic radio would likely work in it's stead.

As trebuchet03 said, it would be interesting to see if another OBD II compliant gizmo caused the same problem.

.....

I wish I had the URL, but I remember reading that it is *possible* for the scangauge to program some settings of the car ECU/PCM, but it depends on the capabilities of the car computer.

If I were a car ECU/PCM, I would likely be annoyed by the scangauge because it would be like an impatient child in the back seat ...

What's your MPH? ... What's your TPS? ... What's your RPM? ... What's your IAT? ... Are you going to eat that? ... I know your MPG! ... What's your MAP? ... What's yout WT? ... Are we there yet? ... What's your MPH? ... What's your TPS? ... What's your RPM? ... What's your IAT? ... Are you going to eat that? ... I know your MPG! ... What's your MAP? ... What's yout WT? ... Are we there yet? ... What's your MPH? ... What's your TPS? ... What's your RPM? ... What's your IAT? ... Are you going to eat that? ... I know your MPG! ... What's your MAP? ... What's yout WT? ... Are we there yet? ... What's your MPH? ... What's your TPS? ... What's your RPM? ... What's your IAT? ... Are you going to eat that? ... I know your MPG! ... What's your MAP? ... What's yout WT? ... Are we there yet? ...

CarloSW2

[cfg83]

regor -

Just a thought, I wouldn't do this without full knowledgeg. I suspect there's a special wire going to the radio that could be cut that would stop this.

I also think this could be a Silverado-forum question.

I just googled "scangauge radio reset" and found this :

new to scangauge - Scangauge | Google Groups

Hi, I just installed a new Scangauge ll in my 2002 GMC pickup truck.
It is a 5.3l gasoline engine. The Scangauge itself seems to work
great, but everytime I shutoff the engine and restart my clock in my
radio goes to 1:00 o'clock. Resetting the clock will not retain
setting. Can someone tell me if there is a fix for this problem. I
also want to make an xgauge for "this tank average MPG". Any help will
be appreciated.

Thanks in advance.

rgw3955

A GMC is still GM, and 2002 is real close to 2001, so the above looks like a (slightly?) different flavor of your problem.

CarloSW2

[PaleMelanesian]

I can almost guarantee your Civic does cut off the fuel when it's in engine braking. Mine (1996) does. You'll just need to adjust the "cutoff" setting on the scangauge. It should be explained in the manual.

[MetroMPG]

Originally Posted by cfg83

If I were a car ECU/PCM, I would likely be annoyed by the scangauge because it would be like an impatient child in the back seat ...

You forgot: "I need to go to the bathroom."

Thanks for the chuckle!