EFI COnversion Wiring Questions

[jcc911]

Hey EFI experts.
I am working on finising up wiring my MS2 and I wanted to double check where I am making the connections.

I could not find a diagram that matches the wires of my harness so you help would be greatly appreciated!!

Here is a list of the wire on my harness (sorry I do not have wire sizes).

2 Green/white striped
2 Blue/white striped
1 purple
1 pink
1 heavy Red
1 "thin" red
1 shielded grey
1 brown
1 green
1 yellow
2 Heavy black

Thanks for your help! JC

[gestalt1]

this should clear things up:

[rfuerst911sc]

Did you buy this harness or make it? Usually when you buy these harnesses they have a schematic telling you where each wire goes. Also the Megasquirt website has schematics showing which pins of the DB37 connectors to use. I threw out all my notes when I sold mine. Good luck.

[jcc911]

I bought it second hand unused and no diagram came with it. I have been trying to figure out where it came from but have not found it. I have been to the MS websites, but still have questions.
Thanks so far for the help.

PS i was not planning on using a relay board...

[rfuerst911sc]

I found the relay board to be a real piece of crap I think you're much better off without it.

[jpnovak]

If it is wired as a MS typically is then the following would be the assignment.

2 Green/white striped - IAC stepper
2 Blue/white striped - IAC stepper
1 purple - fuel pump out
1 pink - O2 sensor in
1 heavy Red - ? usually only one switched 12V
1 "thin" red - power in - switched 12V
1 shielded grey - tach signal from points or other
1 brown - ?? MSII ignition output?
1 green - Inj 1
1 yellow - Intake air temp or coolant temp
2 Heavy black - system grounds

The best thing you can do is slide back the DB37 cover and verify pinouts to color code. otherwise you will always be guessing why your system may not work.

Maybe you could inquire to your source as to who built the harness.

btw, my install does not have a relay board either.

[jcc911]

Thanks JP
There are actually two heavy red, and beleive they are the 12v for each bank of injectors. Therefore the the thin red powers the MS.

WHat are IAC steppers? Are they needed?

[jcc911]

OK some of the wires have printing on them...
if you can please let me know what they are connected to, that would be a big help!!!

The brown = 36 pin ???
Yellow = Coolant, would that go to an Air temp sensor ??
Thin Green = F Idle ???

Purple = fuel pump, Where do I splice this if i have a 3.2 intake?

Pink = O2

Shielded Grey = IGN does this then go to the Coil with a tach adapter?

[jcc911]

Where do I get and air temp sensor for this and also the engine temp sensor like the ones in the TBitz kits?

[wswilburn]

I would use an ohmmeter to check which wires co to which pins on the connector. If you get it wrong, it's a pain to fix later and you may damage something. The coolant temp. input is for engine temp. Air temp. is a separate input. You need both. The air temp. sensor usually goes into the side of the filter housing part of the air box. The engine temp. sensor is usually mounted to a ring lug and can be attached to various places on the engine. Tony recommends attaching to a chain cover stud. I seem to get more consistent results putting it under a nut mounting the #2 intake runner to the head. I bought Tony's kit, so I don't know where the sensors came from. The MS page has information on sources. Take a look also at diyautotune.com. They sell many parts for MS installations and have pretty good documentation. The wiring diagram for their harness may help, if it is not exactly the same.

[wswilburn]

The fuel pump wire is to turn off the pump when the engine isn't running. This is mostly for safety in a crash. The MS uses a circuit with an open collector output and assumes you turn on the OC transistor to run the pump. The 911, however, wants you to ground this wire to disable the pump. The type of intake doesn't matter. To get the logic right, you can either change the MS code, or use another relay. I opted for the relay, but I think I fried my OC transistor somewhere along the way. When I get it working, I'll post a circuit diagram.

[wswilburn]

Jeremy,

Check out this thread:

Tbitz EFI + MSII

Scott

[jcc911]

Now things are starting to make a little sense, so the blue/white and green/white are for a stepper motor for and Idle air control valve.
I do have one of these aluminum ICVs, but do not have the motor.

Since I has planning on reusing my AAR, I do not think I need to use these wires.

[jcc911]

Thanks Scott for the help, I have been to DIY before and will have to check that out again.

So I connect the coolant wire to a engine temp sensor...
Which wire would connect to the Air temp sensor?

THe reason I mentioned the 3.2 intake is because for the Fuel cut off, you are supposed to splice into the wire for the fuel metering plate(CIS). Now that my CIS is gone, what would I splice the fuel cut-off in to?

[jcc911]

I would need an Open element IAT correct...

Got it, because the engine is no longer NA, I will need an open element IAT for faster response time.

Now for the brown and green wires...

[jcc911]

F Idle will not be needed because I will be using the AAR... the fast idle solenoid is an "on-off" valve that allows more air into the intake on warm-up.

I guess I have an orange wire for IAC on the connector side, but does not come through into the engine bay, so I need to figure out what happens to it in the harness.

[rfuerst911sc]

jcc911 I believe I have the generic air temp sensor and the engine temp sensor left over from past EFI conversion. You can send me a PM if interested.

[jcc911]

rfuerst, PM sent. Thanks!