Am getting closer to building the Microsquirt wiring harness for the Weber and have been doing a lot of drawing of the harness and reading info from the Microsquirt instructions about "noise"
Have noticed on the "original" snowmobile harness the wire coming from the cranskshaft timing/position sensor is shielded. Apparently it produces enough of a AC signal that it might radiate RF noise, also from the Microsquirt info they strongly recommed that you seperate out the ignition coil leads and the injector leads as far back to the ECU as posssible and shield them as they are a source of RF noise. They state that the "flyback" voltage from the coil can spike as high a 350 volts. I also know from my experience in two way radios that the fuel pump can be a source of noise (sounds a lot like alternator noise) but this can be taken care of by putting a common capacitor filter from the hot lead to ground as close to the pump as possible. Also a SUPER IMPORTANT point for those who might be considering the Microsquirt fuel injection system ---IN THE MICROSQUIRT INSTRUCTIONS THEY STATE THERE ARE TWO (2) SEPERATE GROUNDS, ENGINE OR "PHYSICAL" GROUND AND THE ------ COMPUTER/SENSOR GROUND----- Do not put the sensor/ computer ground to the engine or physical ground or you do really serious damage to the ECU.
After reading all about this "noise" thing I am wondering just how much noise the Subaru conversions might be experiencing especially in the radio department.
post some pictures. If your sensors use the engine as a ground (a one wire sensor) then you used the physical or engine ground on your ECU back to the engine. If your sensors use an independent ground a two wire (which helps eliminate the introduction of noise from several sources on the engine) then you will use the ECU Sensor ground. I think you will find they are interchangable so long as your ground matches the sensor type.
If you post your build with the Micro Squirt, I will post the Mega Squirt II. I would like to see the difference in the two ECUs.
I think the Megasquirt will be the same as the Microsquirt on the ground situation, they even referr to the "other ground " and the "sensor ground system" and caution you to take the "sensor ground" back ONLY TO THE COMPUTER GROUND PIN and not to physical ground. This will of course only work with a two or more wire sensor. Am waiting for all my connectors to arrive from the various sources, intend to crimp connectors directly onto the Microsquirt harness and not use "pigtails" , aslo bought a "proper crimper"
PS the ECU has two(2) seperate ground systems and they are marked as such
yep... that is the ecu i plan to use.... Motec M400... not cheap though... bout a $3000 ECU
but it allows you to tune the engine to much greater detail.... you can tune the motor to run on 87 octane with that ecu if you need to.... allows you fine tune for fuel efficiency at lower rpm and adjust it for max power in upper rpms.... basically with that ecu you can have anything you want within the capabilities of the existing motor.
Hey Mark, have you decided that you are going to use the Megasquirt over the original Bosch ECU?? Are you going to use the original Bosch fuse/relay block (like I am) It makes a great fuse/relay block with just a little modification. Have finally located all the sources for new wire terminal contacs for the fuse/relay block if you want to replace the terminals rather than splice the wires, you will need a proper crimper if you go this route.
If you install new terminals, you can do a little re-programming of the terminals that makes for a neater layout for Micro/Mega squirt ECU/
It good to see you post. its been a while. Thanks for the tip on the ECU. I decide to go with the Mega-squirt II for my build. Mainly because I can use the IAC stepper motor, which the Weber came with.
The Mega-squirt II can run 16 table fuel options or the standard 12. It is programmable for multiple fuel options since it based on Octanes it has no problems with 108 octane or 87. Its a matter of fuel burn and oxygen content. I would think you could run propane with it if you wanted.
As I said, I went with the Mega-squirt II, it came in Friday. I did not bother John with it, because there are so many options as you build it, I though I would learn more by doing it myself.
If you want I can post a few pictures. It builds in 4 or 5 stages, I forgot. Anyway I read the first section and I don't quite understand the Ignition Jumper. So i will have to read up on it some more, then solider the Power supply section together.
The JS10 goes to IGN, or IGBTIN, IGBTOUT jumper-ed to IGN.
I just got back from the Chapter 6 flyin at Magnolia , ARK. So I did nothing this weekend but drive and chew the fat with a great bunch of guys. I needed a break.
I believe my Weber is using the tooth wheel with a hall effect (crank sensor) and a Hall effect cam sensor on the cam lob to synchronize the spark to the Mag cylinder compression stroke.
My Microsquirt was a ready assembled unit, and I don't have the options of program jumpers ( I guess). My choice for ignition options is done by selecting which of the wires that are in the harness (already wired) that I use. I will be using the direct control by the ECU of the coils, not external controls. This will be the crankshaft (tooth wheel) sensor and of the other two options I will be using the one labeled VR Sensor, going to the cam. In my book "INPUT 2 " will go to the Crank and the "INPUT 1" (which has two options) will use the VR option going to the cam. They get VERY specific about not getting the 2 options on INPUT 1 tied together in anyway. Other than being VERY specific about how to feed voltage to the coils, and NOT getting the SENSOR GROUND tied to the chassis ground, it's pretty much a easy go.