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Old 07-22-2009, 07:32 PM   #1 (permalink)
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Join Date: Jul 2009
Location: Eureka, CA
Posts: 16

Daisy - '90 Toyota Corolla DX
90 day: 43.82 mpg (US)
Thanks: 2
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MPGuino rebooting and freezing also... Power issue?

I've browsed the many fine posts relating to the MPGuino locking up but still haven't found an answer yet.

Here's a brief history of the problem:

A mechanically-minded friend helped me install it in my 1990 Toyota Corolla 5 speed. (We also installed a tach and a vacuum gauge.)

We tapped the injector wire, ran a wire from the combination meter's VSS port, tapped an always-on 12v+ wire from either the stereo or the clock memory (can't remember which) and added a bolt to the firewall and ground both the MPGuino and the tach to it. All of these wires run to an RJ11 box so that I can easily plug and unplug the MPGuino if necessary.

We fired it up and configured the values (injectors for my 1990 Corolla seem to be in the ballpark of 322620341 usec/gal if you have the same injectors) and it worked great.

BUT... when doing EOC or turning the engine off/on, it would often reboot and lose my MPG info (especially when turning it off for some reason).

So, I tried running a wire directly from the battery (but kept the initial ground) and now its even worse! It reboots constantly while the car is on, totally loses all memory, and finally freezes and I have to leave it unplugged for a while. Also, the VSS doesn't even seem to register on the unit anymore. Curiously, as long as the car is OFF, the unit will run indefinitely. I tried running it with both the VSS and/or the INJ cables unplugged to see if they were the culprit, but it still misbehaves with just the power input.

I'm not sure what the problem is. Do I need to install some kind of car-based UPS to clean up the 12V power? I know a car's electrical system can very greatly in its output.

Thanks a lot and I hope my post makes sense.

PS: I'm not too good under the hood but I love FE had SG envy and so the MPGuino was a dream come true for me. A big THANKS to all the effort that went into producing it!

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