I have a '94 3.4L 5-spd camaro and have been running
Megasquirt on it for ~3 years(as of June-04) and it's been working out great. I
started out with it controlling fuel only but I have since added the capability
for it to control the stock GM DIS ignition as well. Between that time I had
also adapted a ford DIS system before I figured out how to make the stock DIS
work but I have since taken the ford system off.
Now, to give some perspective on price and what it takes to get where I am
today, you can either buy a complete unassembled kit and built it yourself if
you know how to solder(it's really not that hard with the right iron, etc), or
you can buy an already assembled megasquirt.
The kit I am running that has the capability to run fuel and spark(and a bunch
of other features such as N2O, cooling fan on/off, etc) will run you $140
unassembled from www.glensgarage.com.
It is the V2.2 mainbaord with the MS-I processor (not MS-II). I say it has the
capability because after you build it to spec with that kit it comes with the
original code flashed into the processor and there are also some minor hardware
modifications needed to run the ignition control. These modifications include
flashing in new code and soldering in 2 resistors that only cost a few cents and
running a couple of jumper wires on the board. I have written up a guide on how
to do this for the megasquirt version I'm running.
You can buy a completely assembled version of the $140 kit for $240 from www.diyautotune.com.
Now, for the code that has all the extra features, it is free for download and
can be flashed in yourself. All you need is a computer with a serial port and a
serial cable. The site for that code is here(it's called
Megasquirt-n-spark-Extra, or MSnS-Extra): http://megasquirt.sourceforge.net/extra/
Check out all of the features it has.
Now this is pretty much the cheapest route to use the megasquirt to get full
fuel and ignition timing control on a 3.4L V6. I did it for slightly less by
buying the basic kit directly from www.megasquirt.info
which is just the bare mainboard, the processor with code, and a few other key
components for $60. I then scrounged up the remaining parts and managed to
assemble that same $140 kit for ~$100. You can do this too if you know your way
around simple electronic parts and know where to find them for cheap.
Now, from there megasquirt just starts getting more expensive. You can get a
MS-II processor and plop it into that V2.2 board but just the MS-II processor
alone is $82 from www.glensgarage.com.
You can also use the V3.0 mainboard with either the MS-I processor or the MS-II
processor. The V3.0 mainboard has extra features that the V2.2 does not have
such as a built in VR circuit(for ignition pick-up, etc), the ability to run
either high or low impedance injectors(the V2.2 by itself will only run high impedance
without adding an extra "flyback" board), and a built in single coil
driver so if you had a distributor with one coil you could drive it directly
without an external ignition module. The MS-II processor has a lot more
potential than the MS-I processor but right now it doesn't have as many features
as listed on that site for the MS-I code I'm running(MSnS-Extra). It does have
support for running a stepper motor style IAC valve however. At this time I'm
not running any type of idle control. I just set the idle with the idle set
screw on my LT1 throttle body high enough so that when the A/C is on the engine
won't die. There are options for adding idle air control with a MS-I processor
without using the stock GM stepper motor, I just haven't fooled around with it
because my setup is working fine for me.
Now, for a breakdown of hardware prices:
MS-I with V2.2 mainboard:
$140 unassembled (glensgarage.com)
$240 assembled (diyautotune.com)
MS-I with V3.0 mainboard:
$189 unassembled (glensgarage.com)
$329 assembled (glensgarage.com)
MS-II with V2.2 mainboard:
No one really carries this combination because it was kind of an intermediate
step before the V3.0 board came out, but you could buy a MS-I\V2.2 kit and the
MS-II processor for $82 if you really wanted it. So let's say:
$140+$82=$222 unassembled (glensgarage.com)
$240+$82=$322 assembled, you would have to add in the MS-II yourself. If you can
install a processor in a PC you could install this one. (glensgarage.com)
MS-II with V3.0 mainboard:
$250 unassembled (glensgarage.com or diyautotune.com)
$400 assembled (glensgarage.com)
ALL subsequent code versions to flash into the processor are free to download
and flash in yourself and people are improving on it by adding extra features
all the time. The tuning software is also totally free and they have PC, Linux,
and even Palm based versions. The only thing you pay for is the initial
hardware.
Now let me explain all of what I'm running with my MS-I, V2.2 megasquirt.
I'm controlling fuel and ignition timing. I'm feeding it a wideband O2 signal(an
Innovate LC-1) and after you get your fuel table pretty close it will target
desired A/F ratios based on another table. So I can have it run closed loop 14.7
when I'm just cruising down the highway and I can also run closed loop 11.5 AFR
when going WOT and under heavy boost. The megasquirt also turns my cooling fans
on and off at temps I chose. I have played around with knock sensing(w/ ignition
retard) but I was getting too many false readings. Actually I haven't devoted
all that much time to making it work right. I have also played around with
electronic boost control and it worked for a while but I need to get a better
solenoid valve that is connected to the wastegate. This kit comes with a MAP
sensor that will go up to 22psi boost. You can swap out MAP sensors to get much
higher if need be. I have also hooked up a pressure transducer to measure
exhaust backpressure and I use the megasquirt(and a laptop) to log it. I did
this too see how much backpressure is in the exhaust before the turbo. You could
put this pressure transducer anywhere such as to measure fuel pressure, oil
pressure, whatever.
And just FYI, I'm not sure if any of those venders will sell you a megasquirt
that's ready to just wire right in with all of the options I listed. If they
would, they would most likely charge you extra. But the modifications really are
minimal for ignition control.
Right now the only thing my stock computer is doing is turning the A/C
compressor on/off and controlling my speedometer.
Now for the drawbacks.
Unless you want to devote a bunch of time in playing with custom programs and
things it's not going to control emissions hardware such as EVAP solenoids, AIR
pumps, and EGR valves. You might be able to trick the stock PCM enough into
thinking it's still in control and have it control those things but I've never
tried. You might be able to do the same thing to get the stock computer to
control a 4L60E transmission. There are some who have tried to control it with a
megasquirt but I believe it takes 2 megasquirts...one for the engine and one for
the transmission, I think this is something they are working on to get 1 to
control both.
Also, as of now megasquirt is batch fire ignition, not sequential. But they are
working on it and getting close. It will require using a MS-II processor. Check
out this site about it: http://www.megamanual.com/router/
As you see there it might be coming out as early as mid-2007.
Just to give you some perspective, with my setup I'm getting 21-21.5
miles/gallon on my daily work commute in my car. I never got higher than 19 when
this car was totally stock. I achieved this through tuning for optimal economy
during highway cruise only. I still run retarded ignition and 12-11.5 AFR when
under boost and I boost as high as 10psi on my totally internally stock motor.
So stock SFI = 19mpg
MS-I batch = 21.5mpg with economy cruise tuning(2000-3000rpm, and ~10inHg
vaccumm)
Also, on this stock motor I have run a time of 14.2 @98.8 mph in my 3550lb race
weight camaro with street tires and 10psi boost.
Here is a list of sites for more information:
www.megasquirt.info -
the main info site
www.msefi.com - the message
board
http://not2fast.wryday.com/megasquirt/mt/2.25/
- the tuning software
Hopefully that gives a pretty good overview of the Megasquirt option for the
3.4L. It is of course not limited to the 3.4L but I just wanted to give the
story of a sucessful setup and user.