Vacuum gauge

[MetroMPG]

cfg: you're the linkmaster. Good info in those links & attachments.

Tomorrow I'm going to look into my idea of using a voltmeter to read the electronic vacuum sensor that is in most cars. If it works the way I think it will, it'll be MUCH easier than installing a vacuum gauge.

[Coyote X]

A digital voltmeter would be cheap and easy to install but will only work to show you vacuum at a 0.5 second sample rate or whatever the voltmeter does. So with that you will not be able to see any jitter or needle vibrations from an engine problem.

You can find a cheap diagnostic type vacuum gauge at advance auto/autozone for under 20 bucks that works great. It isn't backlit but that would be easy to wire in if you need it. The great thing is you can see a lot more about how smooth your engine is operating with that needle than you can measuring any sensors. You can tell when it is time for a tune up or any small vacuum leaks that would be impossible to detect otherwise.

Either way will be good enough to help control your throttle and improve mileage but with a vacuum gauge you can get a lot more information and keep your car running in top condition.

[MetroMPG]

I was thinking of using the DMM solely as an efficiency aid, rather than a diagnostic tool.

So, even if the sample rate off the sensor is low, do you think it'd work OK on an otherwise healthy engine just to give the driver feedback at cruise?

[MetroMPG]

Now that I think about it - the sample rate on the ScanGauge while watching the "instant" fuel consumption isn't any better than 1/2 second...

Edit: and btw - NICE SIG image, Coyote! Is it dynamic?

[Coyote X]

ebay link here is the voltmeter I have connected to my wideband, it would work just fine to connect to pretty much any sensor on the car. It samples at around 1/2 second but for non diagnostic stuff it works great and is cheap enough to put several in monitoring different sensors if you wanted.

Also the sig is dynamic, I am reworking my site and it will be building a gaslog on there when I get time.

[cfg83]

Coyote X -

Originally Posted by Coyote X

ebay link here is the voltmeter I have connected to my wideband, it would work just fine to connect to pretty much any sensor on the car. It samples at around 1/2 second but for non diagnostic stuff it works great and is cheap enough to put several in monitoring different sensors if you wanted.

Also the sig is dynamic, I am reworking my site and it will be building a gaslog on there when I get time.

Kudos on the website. Great stuff. If you go to the ebay store for this seller and search "Auto", you will see lots of other digital meters for cars. By searching for "Auto", it seems like the input power voltage is setup for 12 volt cars (5-15 volts). Here's another voltage meter :

19.999V dc RED LED Auto Digital Panel Meter Voltmeter
http://cgi.ebay.com/19-999V-dc-RED-L...QQcmdZViewItem

CarloSW2

[cfg83]

MetroMPG -

Originally Posted by MetroMPG

cfg: you're the linkmaster. Good info in those links & attachments.

Tomorrow I'm going to look into my idea of using a voltmeter to read the electronic vacuum sensor that is in most cars. If it works the way I think it will, it'll be MUCH easier than installing a vacuum gauge.

Thank you, that's a deliberate goal on my part. I try to write responses that will (hopefully) be useful to you and the next person that might read this months or years from now.

Carl(inkmaster)oSW2

[htaylor]

Thanks for the information on vacuum gauges. I ordered the one from
Auto Vacuum gauge - Save gas and your engine
It comes with all the hoses and fittings. seems like an excellent price only $15 My 95 metro can't use the scangauge

[PaleMelanesian]

FYI, accelerating at 75-80% load, as reported by the scangauge, corresponds to about 12 psi MAP. At 1500-2000 rpm, that's the optimum BSFC point for most engines. Useful for P&G. A simple vacuum gauge won't tell you about P&G, it'll tell you to use super-light throttle all the time. That's good, but not always the best. Do some reading about P&G and about BSFC.