Megasquirt on my Metro XFi

[Coyote X]

I have now driven the car 100 miles with the megasquirt installed and have the fuel tables pretty much where they need to be. I have some knock under load under 1000rpm I need to get lined out but other than that the car is running great. But I figured it was time to share my progress with everyone here.

To put it in perspective I have modified the engine by shaving the head 0.040 to get the compression to around 10.5:1, advanced the cam slightly, ported and polished the head, free flowing exhaust, smoothed and deburred the throttle body/intake, and installed a windage tray and crank scraper. All of this made the car run pretty far out of tune, I hooked a voltmeter to the oxygen sensor and the readings were all over the place and the plugs where showing it running rich. After installing the wideband sensor it confirmed the car was running super rich and there was nothing I could do to get the factory computer back in range.

So after looking around at Megasquirt options I came across http://mtengineering.ca they have a basically plug in setup available for a metro for $325 plus shipping. enquiries@mtengineering.ca is his email. I got this setup and you can pretty much just unplug the factory computer and plug it in. You have to run a vacuum line from under the hood to the megasquirt though so it isn't totally plug and play but it is pretty close. Using the wideband sensor lets me set the computer up for lean burn at cruising speeds. I am running the Hires megasquirt extra code variant to get the injector timing down to a really precise number.




My current configuration as well as the HR Megasquirt installer can be downloaded so you can play with the numbers and see what is possible on this setup. I have set it reasonably conservative on the target air fuel ratio for now but I will be moving up to maybe 17.5:1 crusing after I get a MSD ignition box installed to get a good solid spark in it. Right now the car runs smoother and has more power than it has ever ran in it's life. The engine has always shook a little bit at idle and you could feel engine vibrations at speed but now it is dead smooth at idle and very smooth and noticeably quieter at speeds. I can let it idle in the yard and not make a black spot on the grass from the tailpipe. Overall I am very happy with this computer and can say that if are going for the highest mileage possible and can afford the $325 for the computer and $200 for the wideband oxygen sensor then you will pick up a pretty good gain in mileage. You will also have more information about how your engine is running and can configure all the stuff directly instead of having to trick the factory computer into doing stuff it does not want to do. Getting lean burn is simply a matter of setting your target air fuel ratio in a table and the computer will get it there for you.

I will be filling up probably tomorrow and try and get a good drive on the car to see what kind of improvement I got by installing this computer.

Here is how I modified my dashboard




The computer can show pretty much anything on the 8 gauges. Once I build a small speed sensor circuit it can give a MPG reading on one of the gauges. Then I will finally be able to actually see how my driving is affecting my mileage.

[baddog671]

Sounds like a lot of work. Shouldn't you be well over EPA?

[Bill in Houston]

Too cool. Can you post a screen shot of the AFR vs MAP and RPM like you did when you were asking about target AFRs?

[Coyote X]

With all the mods I have done to the car most people think I should be well beyond the epa numbers but I drive really really fast

[Coyote X]

This is what I am currently driving with and will probably leave more or less alone until I get the MSD 6A installed. I do need to adjust 1500rpm column to basically the same as the 2000rpm and maybe lean out the cruising area just a tiny bit more.

I plan on raising the entire cruising area 2000-3600 x 46-55 to around 17:1 once I get the MSD in. That should give me a good jump in mileage.

[Red]

Awesome What kind of computer are you using for the carPC?

[Coyote X]

Fujitsu Stylistic LT C-500 tablet pc running windows xp tablet edition. It is a bit old but gets the job done real well.

Touch Screen 800x600, Celeron 500, 128mb ram, 40gb hd, 6hr battery life. I cut up the mini dock and mounted it into the dashboard so I can just drop the computer in place and go.

[Jim Dunlop]

Cool stuff.

[DaX]

You know I always wanted to do Hondata on my car and set it up really lean - kudos to you for actually doing it!

[jharbert]

That's pretty cool. I've been considering using a MegaSquirt on my Metro as well. I look forward to reading about the impact on your mileage.

[baddog671]

Originally Posted by Coyote X

Fujitsu Stylistic LT C-500 tablet pc running windows xp tablet edition. It is a bit old but gets the job done real well.

Touch Screen 800x600, Celeron 500, 128mb ram, 40gb hd, 6hr battery life. I cut up the mini dock and mounted it into the dashboard so I can just drop the computer in place and go.

Sounds like its more expensive than my car x5!

[Coyote X]

It is a celeron 500 computer so it is getting old and cheap. I see one on ebay for $200 right now but it is not a good deal. I got the computer, dock, wireless keyboard, car and ac power adapters for $350.

I guess you can say I am past the point of only spending as much on mods as I will make back in gas. I am now spending way more on mods than I can save in gas. But that is typical for me I guess, I usually start out with a kind of normal car then I get bored and I start going nuts with it

[Bill in Houston]

All in the name of science... Nice work.

[MetroMPG]

This is very interesting.

I always think, "yeah, but what about emissions..." when people start talking about modding the stock maps & A/F ratios in general.

If that's a concern, I guess you could befriend one of the guys who runs an e-test dyno and test the changes to the car.

Looking forward to future MPG reports.

[mrmad]

Very cool. Are you using an Innovate LC-1 for a wideband? Also, have you seen David Andruczyk's Megatunix software? Since you have a PC in there, you can customize guages with it.

http://www.msefi.com/viewforum.php?f=76&sid=dbec46846875b69826beb02ddbc 25963

[baddog671]

Metro, there is a dyno business in Buffalo NY that did some work on my dad's stang. I've always wondered if they could "work in reverse", tuning to make the car more fuel effiecient, other than working to squeeze out hp regardless of fuel.

[88HF]

very nice mod, who cares that you don't make the money back... experience is invaluable. Only matters if someone can do it for less, same experience. But you still did it first.

[Coyote X]

I guess when you run a car lean you get more NOx than normal so it might not be great for emissions but then again I still have not gotten around to putting a catalytic converter back on the exhaust so I guess it really doesn't change much coming out of the tailpipe.

I figure cars around here make no difference to the area's pollution since you have no idea what kind of mess they make with the emissions from coal mines around here. If you have a carbon monoxide detector in your house it will go off randomly if you are downwind of a mine. Mines around here are really bad for your health.

I am using the LC-1 wideband it is a pretty nice little device. Well worth the money they want for it. I would like to take my car and dyno tune it one day and get the fuel maps dialed in perfectly but with the wideband on the car it really isn't as important to dyno tune a car as much as it used to be. I figure the car is putting out less emissions now than it was since the car is running closer to ideal. But without finding a shop with a tailpipe sniffer around here there is really no way of knowing.

Also if anyone has downloaded the map I put on the car notice I put the fuel cutoff while coasting down to 1250rpm So pretty much any time I let off the gas it cuts the injectors There is a lot of stuff you can tweak to help mileage so once I get some miles on this setup it might be pretty impressive.

[diamondlarry]

Originally Posted by Coyote X

I guess when you run a car lean you get more NOx than normal so it might not be great for emissions...

That's not neccesarily true. If you can get the combustion efficiency to go higher, the mixture will burn quickly enough that the temp won't have time to get hot enough to produce NOx. In the short time that I got to drive my first Saturn that had the modified head, I noticed that the coolant temperature was lower after the mod since the combustion event was happening much quicker.

[Coyote X]

Well not being able to leave well enough alone....



I also lowered a bunch of other settings and it seems to be running ok. Now it cuts the injectors when coasting in gear at anything over 1200rpm and when decelerating but still under throttle it cuts the fuel by 50%. As well as no warmup enrichment after 30 degrees C. Car is still running smoother than it ever has before. I updated the msq file in my earlier post so download the new one and look around at it if you want.

[mrmad]

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?

[Coyote X]

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.

[88HF]

didn't you say you have instant FE readout with this? What is it telling you?

[Coyote X]

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.

[mrmad]

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.

[Colin]

On that same note, why not upgrade to Megasquirt-n-Spark Extra? You'll have the 12x12 tables.

[88HF]

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.

[Coyote X]

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.

[minic6]

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.

[88HF]

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.