Don't make the mistake I did with MPGuino

[hummingbird]

I bought an MPGuino a couple of years ago. It was a great tool while the initial euphoria held. Then it started giving trouble - resetting itself without warning.

As soon as it resets, it starts giving out garbage instead of useful MPG values, and it is a pain in the neck. I kept forgetting the parameter values, and it was a pain to enter them even if I had them handy with me. And doing this potentially each week or even more frequently was getting on my nerves as well as my wife's nerves.

So off it went after a while. I kept the wiring with 2 signals, battery and ground , and kept the wire coming inside the cabin neatly coiled inside the glove compartment in the hopes that I would get my hypermiling mojo back at some point in the future.

However, over time, the wire must have rubbed off the firewall port and stripped it's insulation when I undertook a 2300 km cross-country journey that had some pretty rough roads (in spite of all having been designated as state level or national level highways! :/ ). This led to the wire connected to the injector signal getting grounded intermittently, leading to some loss in FE as well as power, with some characteristic unburnt fuel smell.

I initially blamed this on the poor quality of fuel available enroute. It can be pretty rough out here, on not-so-well-maintained highways. By the time I came back, I had my regular ~50 mpg FE languishing at ~30. I didn't get the connection and blamed it on bearings, spark plugs, and other sundry reasons, at the behest of my mechanics. Nothing helped.

I was also misled by the ECL indication going ON for a few times, and when we read out the codes, it was high O2 sensor. The service center guys just reset the ECU saying "it can happen sometimes. Come back if it persists".

And persist it did. When I went to them the second time, the FE was as bad as 7 mpg. I was just bleeding fuel.

The second time, when the mechanic looked that the engine, he made me go through all the hoops like throttle body cleaning, injector cleaning, spark plugs change (in spite of them being new -about a couple of weeks old, but not from authorised service center). Then he chanced upon the injector signal tap. He broke it off, without even the courtesy of asking me for it. I too was too tired at this point to object vehemently. The problem was solved, but it cost me about INR 20k (~USD325) in fuel, parts and labor, while the malady persisted.

The moral of the story is, please take care of your wiring, if you have MPGuino installed, and when such symptoms show, suspect the MPGuino wiring for a short to ground. It can save you a lot of heartburn!