Scanguage vs MPGuino - 96 Prizm

[justjohn]

Hey guys,

I'm interested in monitoring my instantaneous mpg, (largely because I want to run some controlled tests to determine the most efficient acceleration method).

MPGuino vs Scangauge

As I understand it the Scanguage is:
More expensive
Needs OBDII
Less Accurate

But the MPGuino is:
Harder to install
Not easily removable
Displays only one readout at a time


As such, I'm leaning toward the MPGuino, but being non-removable bothers me a little, and I'm worried I won't be able to install it correctly. So,

1. Does anyone have suggestions?

2. Has anyone put an MPGuino in a prizm before that could help me if I get stuck?

[dcb]

If you aren't really sure you understand how to install the guino and/or if it will work w/your vehicle I would suggest the SG. I've heard figures that it is within 3% to 5% accurate which is a huge improvement over nothing. And it comes with warranty and paid support people. The guino is really targeted at pre-96 and geeks on a budget. The truly geeky just build their own mpguino

[Daox]

I'd go for the scangauge. The mpguino is great for preOBDII, but the SG just has so many more features.

Accuracy can be tweaked pretty close, but you really just need to get a baseline. From the baseline you can tell if you are doing better or worse.

[justjohn]

Thanks for the input. I'm a little worried about inaccuracies when the car goes into open loop.

Since the main thing I want to test is efficiency of different modes of acceleration I need to know for sure that it's going to be accurate at full throttle. A couple other threads suggested the scangauge gets off significantly when the air ratio changes (ie: especially in open loop).

That being said, would you still go with a scanguage?

[Daox]

If you are doing open loop testing, neither will be absolutely accurate. In open loop, fuel is just being wasted to enable easy starting in cold weather, or its injecting extra fuel to cool down the combustion chamber due to ping/knock. You don't know how much extra is being injected. And, there is no easy way to calibrate either of them to get close unfortunately, unless you get on a dyno and do some serious testing.

[dcb]

well, the guino is watching the injector so it should not be faked out by open loop(and it does display more than one thing at a time), but john you are ultimately responsible for making it work on your vehicle and may have to do your own research to see if it will work and how to make it work (or who to buy a case of beer for to make it work), the guinos are not consumer items where you can try it and send it back if you don't like it, just fyi.

[justjohn]

Originally Posted by dcb

well, the guino is watching the injector so it should not be faked out by open loop

See, that's what I was assuming.

Daox sounds like he's saying there's a way for fuel to get in there that the guino can't see. That doesn't seem likely to me, but my car knowledge is relatively limited. Can anyone reassure me one way or the other?

Provided the guino won't get faked out I would prefer it over the scanguage (price is a factor as well). I'm basically trying to get an idea of just how hard the guino is to install.

I can handle digging up some wires and soldering them, but if it's going to be complete guesswork on which wires I want then I might just say forget it.

[Daox]

Its pretty easy to install. I have one on my Paseo. Yes, the mpguino is more precise, and it will not be faked out by open loop. For your testing purposes it is a better choice.

[justjohn]

Alright, I'll probably try the mpguino then. If it's the least bit intuitive I'll be able to figure it out, and the worst that can happen is a couple holes in a 14 year old car, right?

[MetroMPG]

No holes required (for the MPGuino). You just have to find and splice into a few wires.

Also: I can tell you right now, you're unlikely to find that open loop acceleration is more efficient than closed loop.