88_N/A_GXL

iTrader: (3)

I've been wanting to get an ems for a while now, and MS has been very tempting, but until about a week ago I didn't know they had this so I thought I'd have to do a bunch of wiring. Now that I don't have to it's even more tempting but there are about a million different choices with 1, 2, and 3 plus MS3X, JimStim, VR circuits, the Zeal board, etc. that I don't know what I need.

I do know I want MS3+MS3X, I'm thinking this plus that adapter. Would that be all I would need and just connect the two and plug it in and go, after tuning of course? Also, I read somewhere else that some ecu's don't control A/C and a bunch of other options. Would I lose anything with MS?

I'm basically running bone stock fuel and spark except a Jacobs Rotary Pro Pack, any wiring to worry about there? I'm assuming not with the PnP harness connector.

Thanks for any help.

Aaron Cake

iTrader: (1)

Yep, you can use the MS3+MS3X with the PNP adapter. All you'll need to do is wire the MS3 inputs and outputs to the corresponding pins on the adapter, and then run wires to the fuel pump (stock setup switches the fuel pump through the AFM).

You don't really need any kind of stimulator if you aren't building the ECU. You won't lose anything with the Megasquirt. It can receive the A/C request signal and output the signal to turn on the compressor just fine. Or you can bypass the ECU entirely. Not much on the 2nd gen is tied to the ECU besides engine function.

88_N/A_GXL

iTrader: (3)

Sweet, thank you Aaron. Question though, why would I need to run wires to the fuel pump? I understand the whole AFM controlling it, just wouldn't everything work fine with the adapter?

Edit: Forgot to add, would the A/C request signal still need to be programmed into the MS for it to output it? Mine doesn't work right now but these 90+ degree days with 70% humidity are really starting to suck.

Aaron Cake

iTrader: (1)

The stock fuel pump is switched by a relay that is controlled by the ECU and a switch in the AFM. Without the AFM the fuel pump will never run. So you can jumper the wire at the AFM, or just replace those 20+ year old fuel pump wires.

As for the A/C, it is as simple as just jumpering the wires together on the stock harness, or programming an output on the Megasquirt to activate when it receives an input.

88_N/A_GXL

iTrader: (3)

Thanks for clearing up the A/C question. Still confused about the fuel pump though, why wouldn't the switch in the AFM still be active?

YaNi

iTrader: (2)

Because you won't be using the AFM with the megasquirt. It's MAP based, so you can just throw your AFM away. There's no reason to leave it there when it's non-functional, and not required. If you read Aaron Cake's writeup you end up running new 12ga wire all the way back to the fuel pump.

88_N/A_GXL

iTrader: (3)

Okay, that clears it up. I was just assuming with the PnP harness I could just plug it in, tune it, and go. I wasn't expecting ripping things out and running new wires.

I'm assuming the MAP equivalent is the boost sensor on the shock tower and that's what MS3 references?

Also, since the AFM is no longer needed is there a way to wire it open or some way to keep the stock intake routing?

MS3 is turning out to be more work than I was expecting.

YaNi

iTrader: (2)

The Megasquirt has it's own internal MAP sensor, so you will need to run a vacuum hose from the engine to the megasquirt. It will not reference the factory MAP sensor. The only factory sensors it uses are: coolant temp, air temp, TPS, CAS, and possibly the narrowband O2 if you want to use it for EGO closed loop.

You can rip out the flapper in the AFM so that it isn't an unnecessary restriction and jumper the connector so that the fuel pump circuit is closed. When the flapper shuts it opens the fuel pump relay circuit so that the pump doesn't stay running if you crash and the engine dies. I just think it's easier to run a new circuit for the fuel pump and let the megasquirt control the relay.

88_N/A_GXL

iTrader: (3)

Did not realize it had an internal MAP sensor. Also, only reason I asked about the AFM was for restrictions purposes, I realize I need to run a new set of wire for the fuel pump.

Now, to save up the money to finally Squirt the 7.

Jarods7920

Squirt is a good choice, i have done several of them over the years. You might find it interesting to know that recently the MS beat out MOTEC in a shoot out.

Aaron Cake

iTrader: (1)

Where can I find this shootout?

muythaibxr

Yeah, I know of one where we beat some other guys, but I didn't think who we beat was public knowledge (and I'm not even sure which other ECUs we beat).

Was Dieselgeek involved by chance?

Ken

Aaron Cake

iTrader: (1)

Ah, found it via the Google. That's pretty cool. However it does bring up the point: who is going to tune to the level of chasing 1/10th of a degree of timing on a street car? 2nd gen wise, there's a lot more slop than that in the mechanicals of the CAS.

88_N/A_GXL

iTrader: (3)

Finally getting close to d-day on ordering my 'Squirt so I thought I'd stop back in and verify a few more questions I've come up with as I reread through Aaron's guide for about the 30th time, can't really find a guide as good as that that covers MS3.

With this setup am I going to need to add the 2nd VR circuit? How about the BAC mod? E-fan? Pullup resistors? And lastly, for now, what about the CLT and IAT sensors, will I need different ones?

muythaibxr

With MS3, you should be able to run everything on the engine with no mods to the MS. Just get a standard V3 or V3.57 board, ms3, ms3x, hook them together, wire them up per the MS3 manual, and set the proper settings and you should be good to go.

Ken

88_N/A_GXL

iTrader: (3)

Well, it should be delivered tomorrow. Damn, that got shipped out FAST! I ordered it yesterday around noon. Hopefully I should be running by Monday, but I've still gotta rip out the AFM, rewire the fuel pump, and run a vac line into the car.

Aaron Cake

iTrader: (1)

DIY AutoTune is the best company I've ever dealt with online, no question.

88_N/A_GXL

iTrader: (3)

Yea, got mine earlier today. Wish I woulda known that I needed to order a db37 cable. At least it comes with the connector and I'm fairly decent at soldering. What guide would you recommend for wiring the MS3/MS3X to the DIYBOB?

Aaron Cake

iTrader: (1)

Don't know if there is such a guide. If you do have an '88 GXL as your name suggests then the ECU wiring diagrams in the Haynes are accurate. Combined with the pinouts in the FSM for the ECU plug it shouldn't be too hard.

88_N/A_GXL

iTrader: (3)

Yea, I forgot the FSM had the pinout. So following this I need spark A-C, fuel A-D, EGO2, PWM Idle, and Launch under suggested MS3X mode and just match them up to the FSM layout? Oh, and MS3X will control the fuel pump relay but I can't find the pin in the 04a FSM.

I feel like I'm missing some things...

88_N/A_GXL

iTrader: (3)

Arg! That Haynes manual is making my eyes hurt. I suck at reading wiring diagrams. I pm'd muythaibxr to see if he can help me out.

muythaibxr

I do not help people in PMs. Most of the time if you have a question, the answer to that question can benefit everyone else.

Please ask questions about what you're having issues with specifically and I will answer those questions in the public forum.

Ken

88_N/A_GXL

iTrader: (3)

Okay, well, this doesn't tell me anything about how to hook up my A/C request just that it can control it. Page 289, pdf page 9, in the Haynes Manual has the main A/C relay but goes to "F" on the control unit, that doesn't tell me which pin on the ECU that is.

Then, what about fuel pump? DIYAutoTune says it can run that from the stock ECU so I won't need to run a new wire, but what pin is that? Is that 3B on that same Haynes Manual page?

What about my O2 sensor? Does that go to pin 24 on the MS3 or pin 22 on the MS3x?

Also, what about neutral/clutch switches? Or are they even connected to the MS?

FSM says the shift indicator light is output from the ECU so which pin on MS is that go to?

I've got more questions but I've got a class I have to be at in 15 minutes.

muythaibxr

Assuming you have the car in your username (S4 NA):

The AC switch would normally be pin 1E (third from the right on the top of the largest connector). The AC main relay would be pin 1F (Directly under 1E).

On the MS side, you can hook the switch input to any of the pins listed in the AC idle-up configuration page for the input, and the relay can hook to any of the pins on the output setting of the AC idleup page.

On an S4 (I'm assuming yours is) The ECU didn't control this. The AFM turned on the fuel pump when there was airflow through it. There is a fuel pump test connector on the stock harness. For this you can run a wire from the fuel-pump output of the MS to the fuel pump test connector and use that to control the fuel pump.

I would not use the stock O2 sensor. I would replace it with a wideband controller and sensor.

These don't get connected to the MS.

There is no special pin. Depending on how much current that draws, you can wire it to one of the medium-current outputs on the ms3x and set up a generic port output to turn on above a particular RPM.

Ken

88_N/A_GXL

iTrader: (3)

Well then, the DIYAutoTune.com write-up needs to be corrected as it does say just wire to the fuel pump relay wire on the stock ECU.

I never planned on using a NBO2, I've got an Innovate MTX-L but, thanks for the assumption, O2 connection would still be an O2 connection be it WB or NB. Also, you never answered that question after your assumption, does it go to pin 24 on the MS3 or pin 22 on the MS3X?

According to my Mitchell OnDemand wiring schematic, the clutch sw, starter cut relay, neutral sw all connect to the ECU, pins 1L, 3D, and 1G which are also the same in the FSM, so what's to stop the engine from starting in 1st gear with the clutch out on MS3?