Megasquirt on my Metro XFi - Page 3 - Fuelly Forums

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Old 07-04-2007, 06:35 PM   #21
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When you are at the 17.0 afr, is it still running smoothly? Apparently, when you get to lean, the engine will start surging.

Have you got any mpg figures?
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Old 07-04-2007, 09:20 PM   #22
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I drove it a few miles today to get the fuel map adjusted to the new target afr settings. It is still running pretty smooth but with it cutting off the injectors down to 1200rpm it can't catch it before it dies when the engine is slowing down out of gear. So if I rev it up to something like 2000 and let off the gas quickly it will drop down and probably 75% of the time it can't pick up the idle before it dies. This will be something that can be fixed with putting in a working IAC valve since the one in the car doesn't seem to work well with the megasquirt. I could just put the cutoff a bit higher so it has time to get stable before dying but seeing as how I am trying to push the limits, I might as well leave it. I like the way the car drives other than having to hit the starter a bit more often than normal. I will get a good IAC eventually and that will fix the idle problems.

Normal driving at 60-65mph is 3000rpm at 50-60KPa so that is where it is at on the table most of the time, so normally I will be at 15.5 afr. The 15KPa is pretty much only going to happen when coasting down a hill holding the throttle open slightly. The car does seem to run ok with 17 but it does miss some. I pretty much figure that is the fault of the ignition system so the MSD should fix that and let me run maybe even up to 18:1

I filled the car up today using A 2x4 under the left rear tire to get a good fill and I will try and put at least 200 miles on it in the next few days if possible to get a good mileage number. I am hoping it is something good cause it would really suck doing all this and only picking up 1mpg or something.
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Old 07-04-2007, 09:26 PM   #23
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didn't you say you have instant FE readout with this? What is it telling you?
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Old 07-04-2007, 09:34 PM   #24
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I haven't built the circuit to get the speed into the computer yet so right now I don't have any way to calculate the mileage real time. I Could look at the injector duty cycle and try and figure out how much gas is being injected then divide that by the speed to get mileage but that would be a lot of work to do while driving

The circuit won't be hard to build I will probably order the parts soon I am just working on first things first and getting the car running good before I start adding a lot more to it. But the MPG readout will be the first thing I add to it.
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Old 07-04-2007, 09:36 PM   #25
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The megasquirt does not take a vss signal so on its own, it cannot calculate mileage. it is possible to add a vss signal into one of its spare ADC inputs and modify the software to do it.

CoyoteX, I have saved some of the threads on the MS forum on how to do this if you are interested. By the 8x8 tables you are showing, you have an MS I, and apparently this is easier to do with an MSI then an MS II.
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Old 07-04-2007, 09:53 PM   #26
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On that same note, why not upgrade to Megasquirt-n-Spark Extra? You'll have the 12x12 tables.
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Old 07-04-2007, 10:09 PM   #27
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that subaru sambar is awesome. I've always wanted one of those things. They run them on the bike trail around here and I'd wondered if they are street legal. I'd definately prefer one over my ford ranger.
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Old 07-04-2007, 10:35 PM   #28
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I am running Megasquirt-n-Spark Extra the hires code variant actually. The target afr table is a 8x8 table because it really doesn't need to be that big but the spark and fuel tables are 12x12. The stock metro injector is way bigger than the car actually needs so the normal megasquirt n spark didn't idle well, the steps were bigger than it could handle. The hires code is pretty good though the steps are small enough to make it stay right on the target afr. 5500rpm wide open the car is running like 50% duty cycle on the injector so I bet the stock injector could handle a turbo at like 5psi of boost.

http://megasquirt.sourceforge.net/extra/antirev.html has the circuit to build the traction control system. To get the speed into the computer you only have to build the driven wheel circuit and hook it up. I guess building the whole thing and having working traction control would be a good thing but I don't really think I need it. I am not sure of it's accuracy but it should be good enough to do ABA type of testing so that is all I really care about. It can't do average mpg or anything like that so it really isn't going to be a perfect setup but it will be better than nothing.
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Old 07-05-2007, 04:32 AM   #29
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Awesome stuff. Now your getting a sense of what the eng. do everyday. One thing to remember is watch the road! I've seen eng. drive off the road by looking at their laptops to long!!??
This also gives you an idea as to what pleaseability is all about. What were willing to live with versus the everyday world. Plus the constrants of working within EPA requirements. Keep it up and enjoy.
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Old 07-05-2007, 05:06 AM   #30
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Man, grammar check minic. Does not do. Engines drive off the road? Pleaseability? We're not were. constrants? Ahhhhhhhhhhhh! I thought people in New Orleans were bad.
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