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Old 09-17-2008, 11:50 PM   #21 (permalink)
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Thanks! I do understand the basics of engine tuning. I have a supercharged Integra that I tuned with Hondata and a wideband. In Hondata the tuning is done to Lambda, and a fuel map has just one point a map, and you enter in the "lambda" you want for a particular cell for example: (1100 rpm, 30 kpa)= .91 lamba @ 15 degree advance.

I was trying to figure out where Megatune actually "tunes" from, the VE or the AFR voltage. Now that you explained it, it sounds like Hondata functions from the same table, whereas Megatune has it in 2 places. Also, I think it may have something to do with the distributor set up, because it appears to be "retarded", no pinging, but you can hear it in the motor, it sounds sick. I will try to lean out the settings and try again. 30 mins of idling burned darn near 1 gallon of fuel and killed the o2 sensor.

This is my first time around with this set up, so there are many more variables to have to look at like Dist setting and other things that I am not familiar with. The car does start and run, though poorly.

One other thing I noticed, if I try to "shift" the table by a whole point or two, the VE map or Spark map goes cRaZy and puts all types of weird numbers in the cells.

Thanks again for your help. I really appreciate it.

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Old 09-18-2008, 09:50 AM   #22 (permalink)
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Sadly I couldn't find more example MSnS-Extra maps for your engine .

Quote:
Originally Posted by blownintegra View Post
I do understand the basics of engine tuning. I have a supercharged Integra that I tuned with Hondata and a wideband.
Ooops, sorry for the brick on the basics then .

Quote:
I was trying to figure out where Megatune actually "tunes" from, the VE or the AFR voltage. Now that you explained it, it sounds like Hondata functions from the same table, whereas Megatune has it in 2 places.
Yep, MS has two separate main tables for fuel (VE table) and ignition (Spark table).

The values in the VE table are fuel amount expressed as a percentage on 100% volumetric efficiency (simplifying a bit). You can't enter directly AFR settings (neither lambda nor voltage) in the VE table of Megasquirt.

The values in Spark table are degrees of ignition advance.

Then if you want to use Autotune for fine tuning the fuel, you fill the TARGET AFR table with AFR targets (expressed as wideband voltages, not lambda, in MSns-Extra). Afterwards when you activate it Autotune will reference from the Target table to modify on the run the VE table.

Notice Autotune is just an assistant tool for fine tuning fuel, and needs a more or less developed VE table to begin working on. Autotune can't and wouldn't fill a blank VE table.


Quote:
Also, I think it may have something to do with the distributor set up, because it appears to be "retarded", no pinging, but you can hear it in the motor, it sounds sick.
Experiment advancing and retarding a few degrees at idle, if one direction improves and the other worsens that will tell.

Quote:
I will try to lean out the settings and try again. 30 mins of idling burned darn near 1 gallon of fuel and killed the o2 sensor.
That looks waaaay too rich, a 1000cc engine should use less than 1 litre/hour of fuel per hour idling hot, that's about a quarter of US gallon/hour at most.

What is your 'Required Fuel' setting? (Basic Settings => Engine Constants) and flow of your injectors in lb/hour or cc/min?


Quote:
One other thing I noticed, if I try to "shift" the table by a whole point or two, the VE map or Spark map goes cRaZy and puts all types of weird numbers in the cells.
Strange. Maybe you didn't switch the dot from 'scale' to 'shift' in Tools => Table Transform?
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Old 09-19-2008, 09:51 PM   #23 (permalink)
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Okay, I figured the timing thing. Got it to "sound" normal, will need to do more fine tuning. But now I know fueling is an issue. I can tell that my fuel map goes waaaay lean with MAP pressure, because when i disconnect the MAP sensor, the car will rev pretty well, otherwise, it has a nasty "lean" condition. This is based upon the VE table. I have been trying to "guess" the size of the TBI injector, since this tidbit of info seems to be a mystery when searching all over the internet. I am sure that is a major issue with the fueling too. I will try to "tune" that in a bit. Trying to guess injector size is not fun. I did have the car moving with the bad, bad tune. Now with the timing working, I think I can maybe go back to the original fuel map and see what I've got.

The other thing is you can not open 2 windows of megatune to make comparisons of different tunes to try to put something together. Overall, I'm just happy that this thing actually works and is not just a gimmick!

If I can squeeze another few MPG, I'll be pretty happy.

So, to summarize, if I put "voltage" readings in, and make "adjustments" to the VE table, the computer will try to match the readings with the wide band? Also, with the wideband, the megasquirt will handle all of that internally? just plug and play? or do you have to take the leads from the wide band into the car. Because right now, I have a 1 wire O2 sensor.

Thanks again everyone.

Mike
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Old 09-20-2008, 12:45 AM   #24 (permalink)
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Without a wideband it is pretty much impossible to get a good ve tune. If it was me I would just wait till I install the wideband and go to the megasquirt at that time. Also I don't know if I mentioned it but using the high resolution code variant can help if you can't get the idle afr tuned in.

The wideband will have several more wires than the stock one so the best thing is just run them all in as a group and wire them to the wiring going to the megasquirt. The ground and power wires should be tied into the ms wiring so they both are running off a common ground and power source to keep noise down between them.

Once you get the wideband and mess with the megasquirt setup for a while you will get a better idea of how it works. Within a week of messing with it you will be good at it and will have no trouble tuning the car. It takes a good bit of reading and tinkering but it is worth it in the end.
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Old 09-20-2008, 10:29 AM   #25 (permalink)
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Quote:
Originally Posted by Coyote X View Post
Without a wideband it is pretty much impossible to get a good ve tune. If it was me I would just wait till I install the wideband and go to the megasquirt at that time.
Coyote is giving you very sound advice here Blownintegra.

Quote:
Originally Posted by blownintegra View Post
I have been trying to "guess" the size of the TBI injector, since this tidbit of info seems to be a mystery when searching all over the internet. I am sure that is a major issue with the fueling too. I will try to "tune" that in a bit. Trying to guess injector size is not fun.
In this thread they talk of 272 then 400 cc/min, no fuel pressure info:

Metro 3-cyl General Info - GasSavers.org - Helping You Save at the Pump

Being a 1 litre engine with ~55 HP, I'd guess the single injector should flow at least 260 cc/min. The '272' talked above may be correct. '400' seems oversize for the application, but could also be correct if Suzuki just used the same injector from the 4-cyl 1.3 in the 3-cyl 1.0 . Beware this is just speculation based on unreliable internet data.

Quote:
The other thing is you can not open 2 windows of megatune to make comparisons of different tunes to try to put something together.
Yep. What I do to compare is opening one Megatune in my main PC and another one in the laptop.

Quote:
Overall, I'm just happy that this thing actually works and is not just a gimmick!
Megasquirt can work superbly, but the learning curve is a bit steep at the beginning. Be patient.

Quote:
So, to summarize, if I put "voltage" readings in, and make "adjustments" to the VE table, the computer will try to match the readings with the wide band?
You first create a more or less coherent VE table yourself by hand (the car starts and runs better or worse), watching by eye what AFR the wideband display shows you at each combination of kPa and rpm, and correcting by hand when neccesary.

Then if you want to use Autotune for fine tuning the VE table, you wire the wideband sensor to the Megasquirt ECU, adjust the EGO parameters in Megatune for your particular wideband model, and create a coherent AFR Targets table filled with voltages.


MSnS-Extra Software Manual

Then you run the car and activate Autotune. Autotune will look at the AFR Targets table for reference, compare on the run with what the wideband actually displays, and correct VE Table when neccesary.



An example: Let's say you've set a target of 15.0:1 AFR at 30 kPa & 3000 rpm in the AFR Targets table (expressed as, say, 2.5 volts). And previously you've set a value of, say, '66' in the 30 kPa/3000 rpm cell at the VE Table.

You start running with Autotune on, and Megasquirt detects (via wideband) that actually in the real world your engine at 30 kPa & 3000 rpm is running at 12.0:1 (way too rich). Autotune will start decreasing the value at the VE Table 30 KpA/3000 rpm cell: '66' => '65' => '64' ... and so on, until the wideband actually shows the target 15.0:1 AFR. The final value in the VE Table cell will be, say, '53'. VE Table cell corrected, job done.
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Old 09-20-2008, 12:49 PM   #26 (permalink)
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Coyote X, thanks for the head start with the tune, at least the car is up and running because of your info. I will work the wideband once I can get the car to run and rev correctly to start driving it on the street. I wish I had your computer in the dash, but right now, its a computer on my lap in the driveway! Thanks a million for the contacts and the head start info to get me going. The learning curve is steep. Lots of reading, adjusting, and fiddling...I have a PLX wideband, but I want to do a DIY for permanent installation in the car for lean burn.

TELV, what I did is look at my Acura, 1.8 liters, 4 injectors @ 240 cc each, so I figured around 1/2 of that would be about 480 or 440 cc. 440 cc is a normal cc "off the shelf" so that's what I figured would be a good starting point. 270 seemed a bit small because the pulsewidths would be extremely long, and you'd be running close to 100% at 6500 rpm for 3 cyls, even as stock. I believe normally you wouldn't want to be more than 80% or else the injector never really closes. Also you can't be too big or the fuel would not atomize properly.

Thanks again for your help in getting things set, explaining a where to find things in Megatune and you support on this project as well.

Big thumbs up to these two gentleman for their help to my cause!

Sincerely,

Mike
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Old 09-20-2008, 02:04 PM   #27 (permalink)
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Quote:
Originally Posted by blownintegra View Post
... what I did is look at my Acura, 1.8 liters, 4 injectors @ 240 cc each, so I figured around 1/2 of that would be about 480 or 440 cc. 440 cc is a normal cc "off the shelf" so that's what I figured would be a good starting point. 270 seemed a bit small because the pulsewidths would be extremely long, and you'd be running close to 100% at 6500 rpm for 3 cyls, even as stock. I believe normally you wouldn't want to be more than 80% or else the injector never really closes. Also you can't be too big or the fuel would not atomize properly.
Those are well educated guessings, but the real flow rate from reliable source would be the best data. I did a search on the subject but couldn't find any better than the link above .

May be someone has uploaded the Geo Metro or Suzuki Swift 1.0 workshop manual in eMule or Torrent or similar, there you could find the data.

Also these cheap Haynes books are a heaven of information for the Do It Yourselfer:






By the way, if I were tuning a Geo Metro with Megasquirt for low fuel consumption and low emissions, the first I'd do would be kicking off the TBI injection and DIY to multipoint with three smaller injectors firing just upstream of each intake valve. Single-point wet-manifold injection sux big time.
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Old 09-23-2008, 08:10 PM   #28 (permalink)
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Alright! I've finally got it running good and have driven it!!! Yes, I need to get a wideband on it, but finally I have figured out the leaning out issue! I've gotten it to idle very smooth too! Wow! I thought it was a gimmick, but no! I will have to do some tuning to see what I can get with it. I'm pretty stoked right now! I do not have a lot of timing, so it doesn't pull great, but I do think that the car will actually be slightly quicker. I have a basic set up for those who are interested in the 1st gen geo xfi to get started. Thanks to the guys on the board for their help! Maybe I can turbo this silly thing after all???
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Old 09-23-2008, 09:57 PM   #29 (permalink)
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I will be able to get a better tune for you this weekend. I have a good exhaust and other than the timing being off a good bit on the bottom end it should be a pretty close setup on the ve table at least.

Adding a turbo to a single compression ring piston won't last long either Swap to the normal metro pistons with 2 compression rings to get a longer engine life with the turbo. But I figure the turbo will give the car a pretty good bit of power if you add it but it will not help mileage at all.

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