Megasquirt features
 

Does megasquirt have the ability to measure instant MPG or would I need to get a scangauge/supermid to compliment the Megasquirt? It would be nice to not have to spend another 200 dollars after putting that much into the Megasquirt system. I wouldn't mind having a laptop/pda in my car semi-permanently.

Also, what would scangauge/supermid use to measure my mileage? Is my odometer electronic? I think it is a cable that spins from the transmission. Would I need to install a sensor for the gauge?

Thanks for any advice or links you can give me!

Fourthbean

Megasquirt does not take a Vss input, so out of the box, no it does not calculate mileage.

I'm planning on putting a Megasquirt into my CRX HF. To get it to calulate mileage will be a little work, but it can be done. The speedo in my CRX has a cable input and produces a square wave output that is fed into the stock ECU for Vss input. This square wave can be fed into an LM2917 frequency to voltge converter IC, (produces a 0-5V output proportional to speed). The output from this IC can be fed into one of the spare ADC inputs of the Megasquirt and the software modified to calculate mph, an odometer, and then from this, calculate mpg. It will be a bit of work, but that is what I'm going to try. I will then have a PDA in the car to output and log the data.

I will post all of this when I do it, I just have to keep having life expenses from preempting my Megasquirt purchase.

Doesn't matter as Megasquirt allows the use of a wideband O2, which allows for superlean cruise. Miles divided by gallons will still give you an average, and a vacuum gauge on the dash can help determine when you are getting max mileage for throttle position.

Only bad thing about Megasquirt is it's batch fire, not sequential, although they are working on a way to make it sequential. Big Stuff is more expensive, but allows a wideband with sequential, and may allow you to hook up a MPG minder.

For the same money and far less time investment, you could have an E-Manage Ultimate tuning your fuel and ignition curves. The EMU has wideband O2 support as well as digital outputs to control features based on load and rpm. It also allows the conversion from batch fire to sequential. Just a thought. You'll have LOTS of your own R&D time tied up in a Megasquirt system.

Spence

Whoa, same money? Those E-Manage units seem to be ~$500, while a MS kit is ~$150. For $350, I think I'd rather assemble and tune it myself, especially since maps for a lot of cars/setups are out there already, so it's not as much work as it was when they first came out. The more people provide info on different kinds of cars/engines, the less everyone has to do, very OS imo.

Greddy says it is a piggy back Engine management system. Does that mean you have to have an ECU and then install this one on top if it? That wouldn't work very good for me :)

Sounds like more work than I want to get into right now. If you get it working on your crx I would love to read about it and pick your brain.

Not sure if I want to deal with sequential as I would need to drill holes in my manifold and all. Would be much easier to just use a TBI where my carb is.

Unfortunately, superlean cruise is more complicated than simply leaning out your AFRs at cruise. It would still be preferable to have some sort of instant feedback, in any case, I'd think.

I think I messed up my last post...how would you run MS on this since it is carbbed? And I don't think you'll find anything to measure actual fuel use on a carbbed car with only a mechanical vss.

I would put the money into buying another car, :p

EDIT: I didn't mess it up after all.

What complicates it? Setting the cruise fuel map to a superlean setting, slowly leaning it out while monitoring temps, wouldn't be an issue. What other stuff is needed to run extra lean? Aside from emissions worries, which I wasn't considering.

Does a megasquirt know how much gasoline is being used?

SVOBoy -- I was introduced to megasquirt by a friend a few years ago. I always thought the purpose was to make a carbed car into a FI one. LOL

You can do it with a carbed car, just have to throw a TBI from an old chevy or something and get all the little parts needed like the TPS to hook up. Would be more work to an extent I suppose, but I would know how it all worked after hooking up every single sensor and wiring it all up. :)

What is involved in Lean cruise besides editing the AF ratio.

Effective lean burn requires a lot more than just leaning out the mix...the civic vx has a whole load of crap done to allow it to run lean effectively, while something like the RSX will see little benefit from a simple lean condition. Wikipedia has a bit on the vx lean burn and somewhere there is an article where a few folks with a dyno made an AFR v. FE graph on an RSX and found very little improvement...

Ah, okay, I didn't know you were going to convert to FI, I must have missed where someone wrote that part, :p

Linkz por favor? :thumbup:

Gimme a sec, I'll edit this post when I find them. I have issue with never citing unless it's graded, :)

Wikipedia: https://en.wikipedia.org/wiki/Lean_burn

I don't feel like finding any more detail on it, perhaps that PDF on the VX that has floated around can be dug up.

The RSX tuning stuff: https://hondatuningmagazine.com/tech/0510ht_fueleconomy/

That's np, I was mostly interested in the RSX tune since I couldn't google it quickly. Thanks btw!

Does a megasquirt know how much gasoline is being used?

There is code in the MS1Extra code that can do this. I want to use an MS2 which will mean modifying the code to calculate it, but being open sourced, it can be calculated and displayed. Again, it is a bit if work, but with a forum with thousands of users, I'm confident I can find the help I will need to get this to happen.

Interesting reading, thanks. Not much more is needed to run superlean, but it would take a while to find optimized settings, if emissions weren't an issue to you. Have to give this some thought.