Few MS questions

[740 Turbo Brick]

Ive been searching 420A forums for a while trying to find answers to a few questions I have about installing megasquirt on my GS.

This is the kit Im going to be buying: 420A MS kit

This is the write up I have been studying for about 3 days now: MSnS Install

A few questions have arisen, some have very vague answers, some have none. Im just going to rattle them off, any answers would be greatly appreciated.

I have an AEM uego installed, can I hook the NB wire from the uego into the o2 of the MS ecu?

Will I need to buy coolant and air temp sensors or do they come with that kit?

Will I have to assemble my own injector harness?

What is the difference between running the MS ecu wires directly to the coil, vs. using a 4g63 ignitor such as in the write up?

My stock ECU is failing, so Im worried about it supplying power to the fuel pump. How difficult will it be to just unhook the stock ecu, and run everything (tach, fans, fuel, ignition control, speedo) off the MS ecu?

Ive read the new versions of MS II have IAC stepper motor control. Would I be able to hook this ecu up to my IAC to have the same idle control? Ive heard previous versions of MS had no control over the IAC and cold starts and warmup were rough.

For now thats all I can think of, but Im sure when the time comes for me to start wiring/tuning I will have more, and will post them in here.

 

[bullettdsm]

Ok, I'll leave some of the answers to Paul, since he will be better able to answer.

The Uego can be used in conjunction with the MSnS. There are some settings that are required, but know that you can use it. I actually have my wires set-up for quick disconnect/connect of the wideband (for Innovate)

Sensors I'll leave for Paul

I use the stock injector harness. Just need to do a little splicing. Works great.

If you want to go directly to the MSnS for coil, you will need an internal ignitor. I'm not sure if it comes with the kit or not. But I chose to use the Mitsu ignitor basically because I had it and I like to try to use stock parts where I can. I have had NO problems on any of my set-ups with the DSM ignitor. But basically, one ignitor is external and one is internal.

I run my fuel pump on the NA off the MSnS. You can certainly run everything off the MSnS and use it as a standalone. Keep in mind that you will also need the voltage regulator for the alternator (ours is internal in the ECU). Ask Paul on wether or not that is included.

Stepper motor questions, I'l leave for Paul.

Hope that helps a little,

MB

 

[VelocitàPaola]

And I'll pick up there...

MS-II can read the stock temperature sensors just fine. You won't have to purchase GM IAT and ECT sensors.

Using the 4G63 ignitor is a rather antiquated method of adding spark control to Megasquirt (sorry Mark). The ECU in the kit you're looking at includes internal Bosch BIP373 ignitors. These ignitors are relatively state-of-the-art and include over-current protection. The main benefit to using internal ignitors, though, is simplified wiring. You simply connect the two spark control wires in the your harness to the coil, and that's it!

The kit for which you provided a link includes everything you'll need for a complete installation, including the tachometer output circuit, fan control circuit and alternator voltage regulator. For the most part, installation is as simple as cutting a few wires and splicing them to the corresponding wire from your Megasquirt harness.

The ASD and fuel pump relays do require slightly more attention, though. Megasquirt can only sink enough current from one of these relays, but it needs to control both. The best way to accomplish this is to daisy-chain the two relays. Have Megasquirt control the fuel pump relay and have the fuel pump relay control the ASD relay. Like this:

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Megasquirt could always control some version of an IAC, but only recently has it gained support for the stepper motor based IAC's found in our cars. So, yes, it can control the IAC in your car, but that circuit doesn't come with the ECU in the kit to which you linked us.

 

[740 Turbo Brick]

Great info, thanks guys. Im feeling a bit more confident about installing this myself. So far the most advanced wiring Ive done is fully installing a car alarm/keyless entry system myself, so this shouldnt be too terribly difficult for me.

Paul, if when I order my kit, I also order the option service with the stepper motor control, would that be would I need for it?

 

[VelocitàPaola]

Paul, if when I order my kit, I also order the option service with the stepper motor control, would that be would I need for it?

I suppose so... email them.

 

[740 Turbo Brick]

I will do that.

Also found another one. Sorry for all the questions, but I am the type of person who likes to know everything about something and study it before I jump into it.

Do I need to replace my stock FPR with a 1:1? Saw that posted on here somewhere, wasnt sure if its neccesary.

 

[VelocitàPaola]

Do I need to replace my stock FPR with a 1:1? Saw that posted on here somewhere, wasnt sure if its neccesary.

If your car is turbocharged you will need to replace the stock FPR with a 1:1 AFPR. The 1:1 AFPR equalizes the fuel pressure against the manifold pressure.

 

[740 Turbo Brick]

Negative, taking the MB approach. All motor 420A.

 

[VelocitàPaola]

Okay, you should be fine with the stock fuel system, then. Look around for Mark's setup... I know he has it posted somewhere.

 

[#40Fan]

Symtechlabs will make the unit exactly the way you want it. Even provide you with the harness that is labeled. All you would need is a wiring diagram of your out/inputs from your stock computer and you could splice directly into them.

Give them a call. Tell them to hook you up with fuel pump control, fan control, IAC, and even sequential injection if you perfer.

I too have been beating my head against the wall for the last few weeks trying to find the answers.

If you feel brave and think you might want to build your own MS, let me know. I'll give you all the info that I have gathered so far.

 

[740 Turbo Brick]

So is the standard megasquirt sent without sequential injection? I noticed in te wiring the signal for injectors 1 and 3, and 2 and 4 are on the same signal wiring. Does that mean those injectors fire at the same time? If so Ill def, be going for the sequential.

 

[VelocitàPaola]

So is the standard megasquirt sent without sequential injection? I noticed in te wiring the signal for injectors 1 and 3, and 2 and 4 are on the same signal wiring. Does that mean those injectors fire at the same time? If so Ill def, be going for the sequential.

The sequential injection code for Megasquirt is very new. Also, extra hardware must be added to the ECU which significantly raises its cost. Since its inception, Megasquirt has always used a batch fire algorithm, which really works just fine. Besides at idle, the valves are opening and closing so quickly they couldn't correspond to a fuel injection pulse anyway.

 

[96TurboGS]

740 Turbo Brick,

As for the sequential code it is new, but rest to shore it is very stable as I've been driving with it several moths now with factory like AFR's without one hiccup. (The latest) There is a big push for it in MS3, and the latest code is about to be in the next release. The next release will not be an alpha release as it will be the new 3.0 code for ms2. (Combined with the batch firing code) There are no glitches but there are a lot of things you must take into consideration such as the ignition timing, cam timing, AFR, IAC PID (if running closed loop), AE/EAE values. If it's your first time jumping into mega squirt running sequential right off the bat, you may want to search the threads on msextra development. Some very good threads have been lost as the server crashed and they lost everything dating back to july!!! The car pulls a lot stronger than what it did with batch firing method. It will help with them cams you have.

To get a better understanding of how it works check out jeans site....

Sequential Injection Code for MS2

 

[740 Turbo Brick]

Paul, I see your point. If it would be available as an option, I would probably do it, but if its more extensive than what its really worth Ill manage without it. Its going to be a few months before I have saved up for the 420A kit, so keeping the cost as low as possible right now will help me out.

But with the batch fire, wouldnt you get twice as much fuel for the tied up cyls? Say 1 is injecting, 3 is also injecting but it sits on the intake valve until its intake stroke, but then the injector sprays again for that cyl.

Or is it simply one injection for both cylinders, then 2 and 4, back to 1 and 3?

 

[#40Fan]

You can set up MS to only fire the paired injectors once per 720* of rotation.

 

[96TurboGS]

You can select how many injections you want per rev (1-8 squirts). There also is an option for a injector trim table per cylinder with sequential. The preferable settings would be 2 squirts per rev for both sequential and batch. The VE difference between sequential and batch is about 6% (not much of a diff but response time is better), the idle quality is fairly different from the two.

 

[VelocitàPaola]

Paul, I see your point. If it would be available as an option, I would probably do it, but if its more extensive than what its really worth Ill manage without it. Its going to be a few months before I have saved up for the 420A kit, so keeping the cost as low as possible right now will help me out.

Like most things, there are cheaper and more expensive ways of implementing sequential injection. Currently, the cheaper method involves sacrificing peak and hold fuel injectors. Most larger fuel injectors are low impedance, peak and hold injectors.

Sequential injection and IAC control will make the biggest differences at idle. If your car is a daily driver, I would strongly consider them. If you drive your car less frequently, or if it's a track-only car, then I would probably invest my money elsewhere.

But with the batch fire, wouldnt you get twice as much fuel for the tied up cyls? Say 1 is injecting, 3 is also injecting but it sits on the intake valve until its intake stroke, but then the injector sprays again for that cyl.

Or is it simply one injection for both cylinders, then 2 and 4, back to 1 and 3?

As others have said, you can set the number of injections per cycle. The more injections there are, the shorter each one is.

By default, Megasquirt has two fuel injector banks. For four cylinder cars with four injectors, you would connect two injectors to one bank and the other two to the other bank. Then, you can designate how the banks fire; either simultaneously or alternating.

 

[740 Turbo Brick]

This car will still be my DD. My goal is to be able to drive it during the week, and come weekend drive to the track and run 14s. So Im for sure going for the IAC control, we'll see what happens with the sequential injector setup.

 

[740 Turbo Brick]

Time for an update. Ive had the ECU for about a week now. Im just now starting to realize how deep Im in here.... Im about to go to the garage tomarrow and start trying to sort it all out. Im removing the battery, washer tank, and whatever else is in the way on the firewall so I can drill a hole for the wiring harness. From there, start cutting, wiring in, soldering, all kinds of fun wiring stuff. Newest questions/challenges...

Im still wanting to use my AC, but I was told the stock ECU actually controls the power to the compressor. Can I just run a switch to 12v in the car to turn the compressor on? Or is this totally unneccesary and the AC will work fine?

I downloaded a tune file from Symtech labs. It was described as a tune to start a naturally aspirated 420A. Can I just put this in my Tunerstudios and start the car up, tune it out from there?

Probably most important, should I have someone try to get the full tune out of my car, or is it something I should be able to accomplish myself?

After I get it all wired in Ill post pics in my build thread.

 

[VelocitàPaola]

Im still wanting to use my AC, but I was told the stock ECU actually controls the power to the compressor. Can I just run a switch to 12v in the car to turn the compressor on? Or is this totally unneccesary and the AC will work fine?

The ECU doesn't really "control" the A/C compressor; the HVAC system has its own computer do that. The ECU just cuts power to the compressor when it shouldn't be on: i.e. while cranking or at really high RPM's. You can add a switch there in lieu of the ECU, but be sure it's off whenever you're starting the car.

I downloaded a tune file from Symtech labs. It was described as a tune to start a naturally aspirated 420A. Can I just put this in my Tunerstudios and start the car up, tune it out from there?

Sort of... you should really go through and confirm all of the settings first which requires at least a basic familiarization with them. Start here:

MS2/Extra Manual Index

Probably most important, should I have someone try to get the full tune out of my car, or is it something I should be able to accomplish myself?

Do you mean should you attempt to fully tune the car yourself? It's possible, it just takes a little knowledge and experience. You'll get most of the information necessary to do this from the link above.

 

[740 Turbo Brick]

Ok cool. For the most part Im going to try to do everything myself, with advice here and there on how to do things.

Todays Trivia:

Do I have to use the connectors and wiring harness in my car, or can I cut the connectors off a different harness and wire them up to the MS wires? I only ask because I dont really want to hack up my wiring harness in the event I someday sell the car and keep the ECU, I can just plug all the stock connectors in and in theory, have the car run off the stock ECU again. I have a whole harness, so Im thinking of cutting the alternator, intake sensors, crank sensors, and whatever else I need off and just wiring them permanently to this MS kit.

Theres 4 I believe grounds in this harness, I can just ground them all at the same spot right?

Also, what wire do I use for fan control, and where do I tie it into the fans?

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[740 Turbo Brick]

I got some more work done on the wires that I will post up pics of after work.
Mainly I got done a lot of wiring, including the relay for power to the ms box, wiring for temp sensors and coil, vac line for map, few other things.

I figured out the FIDLE wire is for fan control, but I still need to know where to tie it into. I know it will be a relay, but I have no idea where the fan control relays are, or what pin to use.

Also, Im assuming I can just use switched 12v to the power of the coil pack?

 

[740 Turbo Brick]

I just want to add some info I found out to this page, and hopefully in the future someone can use it for their MS install.

The stock coolant gauge in the dash WILL work if you remove the ECU. There is a one wire sensor under the 2 wire one (on 95-96 at least...) that goes to the dash. No rewire needed.

A few wires from the MS ECU can be connected directly to the stock ECU connector harness for ease of installation. For me, so far, I have connected at the ECU, Tach, Fan control, Switched 12v for the MS relay, and fuel pump/ASD control. I am soon going to look into jumping the VSS (speedo) input and output on the connector instead of wiring it to the dash.

To get 5v to the crank and VSS sensors, you can go to Radioshack and get a diode they call a "voltage regulator". Its about the size of a dime, has a 10-30v input, ground, and v output. There are 5v, 9v, 12v and adjustable v outputs. I chose the 5v one. Use a switched 12v power source to power it, put the 5v output to the power of the crank and VSS sensors.

The stock low oil pressure and fuel gauges will work with no rewiring, I believe the battery voltage indicator will no longer work though.

Ive heard this somewhere, that the reverse lights will not work, but they are hardwired into the light system, they will still work.


I will continue digging and finding out more of what needs to be done for a full standalone MS installation.

 

[VelocitàPaola]

To get 5v to the crank and VSS sensors, you can go to Radioshack and get a diode they call a "voltage regulator". Its about the size of a dime, has a 10-30v input, ground, and v output. There are 5v, 9v, 12v and adjustable v outputs. I chose the 5v one. Use a switched 12v power source to power it, put the 5v output to the power of the crank and VSS sensors.

You can actually use the TPS Vref wire to power all of those sensors. They each draw a very small amount of current and can run off +5V, so it's perfectly safe to do so.

Also, a voltage regulator isn't a type of diode. It's a complex device with many passive components and semiconductors, including diodes, inside it.

The stock low oil pressure and fuel gauges will work with no rewiring, I believe the battery voltage indicator will no longer work though.

That's correct; if the stock PCM is no longer installed this light will no longer function.

Most indicator lamps and gauges are connected to their own sensors, as you've been discovering. The battery voltage light and the tachometer should be the only ones that require the PCM for a signal. All of the lighting and such will work without the stock PCM too.

 

[740 Turbo Brick]

Ha, thanks for the corrections. I was asking someone, somewhere if you could use the TPS vref for the other 2 sensors too, but they said not to because it would be drawing too much power to power 3 sensors. And the volt regulator was the way I saw to do it after a while of searching 2gnt, but the post dates were 06 and earlier, so standalone MS in a 420A was still a relatively new thing. I may leave the crank sensor hooked up to the regulator, and tie into the TPS vref for the speedo sensor.

This is definately what I want though, sort of a one stop thread for a mass amount of 420A MS info.