Megasquirt

[Conover]

anyone here ever play with the Megasquirt system?
I've ordered an assembled Megasquirt ECU and harness with wideband o2. I'm going to give it a run on a 2.0L 8V VW engine mounted in a 1979 VW scirocco. I was just thinking that with all this ECU talk going on, someone might have some advice, there are tons of forums and how-to's and such on the web, I know, but I thought it might be fun to toss the subject around here a bit. At the very least I will report on my experience, I expect it to be a fun entertaining one. Hopefully the new system will free up some horses. it will be a basically stock engine to start with, standard bore, stock cam, nothing major done to the rotating masses, so hopefully the results will be somewhat comparable to something in IT trim.

[JamesB]

Cam,


MS is a nice little system and I know a few who run it. I have never worked on it myself, but I hear its pretty strait foward and pretty simple to tune. if you poke around vwvortex.com like the rest of us do I am sure you can find some baseline fule and timing maps.

[Conover]

Yeah, I've found some base line maps. I'm going to be starting the install next week, hopefully be able to tune it on the dyno in a couple of weeks. It should be a fun little car when it's all done up.

[Eagle7]

I installed a MS in my '86 RX-7 a little over a year ago and raced with it last year. I didn't know much about ECUs nor fuel injection before I started and learned a bunch in the process, both about MS and about my car. If you're a tinkerer with time on your hands I highly recommend it. Some of my comments below assume we're talking about a street car, not an IT car.



MS is a very customizable system, both from a hardware and a software standpoint. It needs to be built with the correct options to work with your car.
If your coolant and intake air temperature sensors don't match the "standard" MS sensors, you may need to change some resistor values on the MS and use EasyTherm to calibrate the firmware. Or you could install the "standard" sensors and not have to fiddle with it. If your injectors are low impedence, you may need to have the optional PWM drivers on your MS.
Different kinds of crank/cam sensors require different interface hardware. I had to build a second variable reluctance circuit on my MS to interface with the stock RX-7 crank angle sensor.
If you're doing spark, different kinds of ignition require different output circuitry or mods.
If you're doing spark, you need to be using the Megasquirt-n-spark-extra firmware. Make sure you have the latest version (029w), as there were some bugs in prior versions. Another option is the HR (high resolution) version of the extra firmware.



If you are a tinkerer, you NEED a wideband O2 sensor. You can get a good start at a tune on the dyno, but you'll really want to tweak it afterwards to make it optimal, and you've got to be able to see where your mixture is under all kinds of situations. The least expensive one I know about is about $200 from Innovate.



You've got to have a laptop computer to be successful at this. You'll certainly be using MegaTune. Make sure you also get and use MegaLogViewer (free software) - it's wonderful. You can log long runs and see in detail exactly what happened. It also is very good at processing the actual fuel mixture from the logs and calculating new fuel maps to produce the mixtures you'd like.



If you're a die-hard, get a Palm Pilot so you can log and/or tune without the laptop in the car.

[Conover]

Yep, The box came in yesterday with the innovate WBO2, the assembled ecu, Stim card, cables, GM sensors, etc.

I'm going to play with the Stim card and learn the software this weekend. Apparently I can log data one of two ways, on the Innovate software or on the Megasquirt, with the laptop. This is going to be fun!
Happy Easter!

*edit* For the Record, total investment so far about $700, the wideband is going to cut the dyno cost some I expect, so, we'll see how cheap we can make some good results here!

[Eagle7]

'm going to play with the Stim card and learn the software this weekend. Apparently I can log data one of two ways, on the Innovate software or on the Megasquirt, with the laptop. This is going to be fun![/b]

I don't have an Innovate, but I expect that with their software you can only log AFR. With the WBO2 connected to the MS, the MS software (Megatune) can log AFR plus all the other sensors and the outputs and the internal MS variables.

Sounds like you've got a great attitude. Treat it as a learning experience and you'll have a great time.

Are you doing fuel only, or fuel and spark?

[Conover]

Fuel and spark. This car has been sitting for three years waiting for me to decide what to do and have the time to do it, so I'm not in a hurry, but I would like to get it going of course.

The Innovate software has a plug in for megasquirt that allows you to log both groups of data together and the interface is a little nicer than the Megasquirt, of course I'll have to go into the megasquirt software to do any mapping changes.

It would be nice to have the definition that Motec allows, but even with the limited control I'll have with Megasquirt, it's more than what I get with a stock motronic system. The nice thing about this versus buying a chip to plug into your stock box, is that I can actually tune it to the specific application, every engine operates in it's own environment, the engine controls should be able to take that into account.

[JamesB]

heh, ill stick to CIS tuning right now.

[hakeem]

I'd suggest getting a Palm handheld and getting the PalmLog software (checkout the Palm section on msefi.com) - I have a Palm attached to my steering wheel during races and can take logs of the entire races/sessions and upload to the laptop later. Combine this with the LC1 wideband, and you can use a log analyzer like MegaLogViewer to analyze your datalog and recalculate your fuel table based on whatever target AFR you tell it to. Very cool stuff.

I have some MS related info in my blog: www.eprx7.com