All right here goes. I am going to list what my plug and play adaper wiring is connected to between the MS DB37 connector and the ECU plug I scavenged from an S4 ECU (N326). My car is an `86 S4 NA. I`m using all the stock sensors, coolant temp, intake air temp, throttle position sensor, O2 Sensor. Stock CAS with two opposing teeth removed. I jumpered ECU pins 1E and 1F so the AC will run when I go to the megasquirt.

I used the V3.0 Main Board External Wiring Diagram and aslo the Factory Service Manual diagrams on pgs 4A-30, 4A-31, and 4A-32.

Okay hear goes where I`m at so far.

V3.0 Main Board----------------------------S4 NA ECU
DB-37-----------------------------------------Plug Pins

1
2
3
4
5
6
7----Ne- -----------------------------------------1Q
8----Ground-------------------------------------2C (which is ground per FSM)
9----Ground-------------------------------------2R (which is ground per FSM)
10---Ground------------------------------------3A (which is ground per FSM)
11---Ground------------------------------------3G (which is ground per FSM)
12
13
14
15
16
17
18
19---Ground-----------------------------------------------To body or frame
20--Intake air Temp---------------------------2J
21--Coolant Temp Sensor--------------------2I
22--Throttle Pos. Sensor Signal-------------2G
23--O2 sensor----------------------------------2D
24--Ne+------------------------------------------1T
25
26--Throttle Pos. Sens. Ref. voltage-------2A
27
28
29
30
31
32\___secondary injectors___________/3F
33/ \3H
34\___Primary Injectors____________/3C
35/ \3E
36
37

Also here are the wires for lead and trail coils


neg. LED 14----------------1V
neg. LED 15----------------1U
neg. LED 16----------------1X

I still have a ways to go but its coming along when I have time.

I still need to decide where to get the power from for DB37 pin 28. should I connect to ECU pin 3I (Main Relay) or 3J (battery)

Any input is most greatly welcome and appreciated!!

 

You don't want 2J for IAT. You want 2L.

For O2, I'd suggest using a wideband to tune. The narrowband isn't going to be very helpful unless you're on cruise... but you've got the right ecu pin for it.

You have your primaries and secondaries backwards.

You should connect the MS to the main relay on ECU pin 3I.

Also, If you're not going to use the FPR solenoid in your PnP setup, please remember to connect your FPR directly to vacuum.

Also, either 2C or 2R is the sensor ground ,one of those should go to pin 19. I'll have to look when I get home from vacation to be sure which one is the sensor ground. It should be brown with a black stripe if I remember correctly.

 

2C is sensor common. Why pin 19? Is that allocated to sensor ground? I put mine on pin 8.

 

pin 19 has a separate ground line running to the common ground. It doesn't really make a difference, it just helps isolate the sensors from the power grounds.

 

Okay the IAT is now connected to 2J

I do not have the $350 bucks to spend on a wide band right now. Is there any way I`ll be able to get up and running with the stock NB O2 sensor

Good catch on the injectors being crossed. I DO NOT know how the hell I did that but its fixed now.

Is it better to use the fuel pressure regulator solenoid or just go straight to the manifold vacuum source.

I got pin 19 connected to pin 2C as a ground for the sensors. Do I still need to run more grounds to the DB37 connector at pins 8, 9, 10, 11?

 

The wideband is a recent invention. People have been successfully tuning engines for decades without it. WOT run, kill ignition, coast to the side of the road/track, pull plug, check colour, change jets in carb, repeat... Those days are gone now with the wideband. For $200 (search innovate lc1), you can get an amazing tuning tool that virtually eliminates the labour intensive process of the past. For n/a applications, a NB02 is adequate for basic tuning as well, but it sure is nice to know actual AFR, rather than just a 'rich/lean' indication.

 

Thanks renns, you do have a point. I guess I`ll have to round up the cash to get the wideband before trying to get this thing running fully on the MS.

Does anybody see anything I`m missing on my adapter so far? I`m getting a little punchy from being up way to long. Gonna get a nap I think.

 

you can just take vacuum straight from the manifold. On my PnP units, I control that solenoid just because if I didn't, it wouldn't be PnP.

 

Muythaibxr,
Three questions for ya!

1. I got pin 19 connected to pin 2C as a ground for the sensors. Do I still need to run more grounds to the DB37 connector at pins 8, 9, 10, 11 and if so from where, the harness or chassis or what?

2. What Would I need to do to have my MS control the FPR solenoid? I think the factory ECU pin 2M is the right one to control the solenoid but I don`t see where to hook it to the MS

3. Is there anything else I`m missing to make my "plug n play" work?

I know you have become THE person with all the answers, and it must be quite a strain on your time. I appreciate your taking some of that time to answer my questions as well as the others that fly your way from the other members.

 

1) just use the factory grounds if you're using the factory harness.

2) you have to build a transistor circuit to control this. It'd probably be easier to just disconnect the vacuum line and run it straight to manifold vacuum.

3) I don't think so

 

I believe the new VW Jetta's use a LM1 so it may be possible to get at least the WB sensor for $50 (give or take). Correct me if I am wrong though.

 

you can get the *sensor* for $38 from 1stVWparts.com, but the *controller* still costs at least $150.

You can't just connect the sensor directly to the megasquirt.

 

Thanks rmriggin for the input. I think for now I`ll see if I can get my NA running on the factory O2 (NBO2) sensor. The 7 is not my daily driver although I do drive her as much as I can (weather permitting). Its nice to have a company provided minivan for my sales/light service position at work. I did not put many miles on my personal car before I got my 7. I think my total miles between both my vehicles last year was less than 6 to 7k........Sorry, I`m getting sidetracked.....As I said, I`m going to get running on the stock O2 to start with.

Muythaibxr, for the Ignition wires from the LEDs, Is there a specific pin on the DB37 connector I should use or is any one of 2 through 6 OR 12 through 18 truly unused by MS and okay for this purpose?

As for the fuel pump is there anything I need to do for it to work correctly or is it okay as is IF the air flow meter is left wired stock? (I realize the MS does not use the air flow meter)

 

You can just leave the AFM installed if you don't want the MS to control the fuel pump turning on and off.

You can use whichever of the spare pins you want on the db37. It doesn't matter.

Ken

 

Thanks Ken for the info. I`m wanting to be able to go back to the stock ECU easily, so for now I`ll leave the AFM in place. Thanks again for all your hard work with Megasquirt. Everyone here (at the forum) owes you a ton!

 

Ken, I was using an Dig. Multimeter to check continuity between the ground pins on the DB37. What I get is this, pins 7,8,9,10, 11, and 19 are all connected as shown on the MS Ver.3 Main Board External wiring Diagram. But I can also get continuity through other pins like 12, 13, etc to the above pins. Is this correct or is there something wrong with my assembly?

 

Well I think what I`m seeing is right at least according to the MS site.
Based on the diagram at the bottom of this page.
http://www.megasquirt.info/ms2/pcb.htm
It looks li pin 1, 2 and 7 through 19 are all ground.
I have another diagram that shows only pins 8 through11 and 19 as ground though I`m not sure where I printed it from.

 

well i cleaned it up a lil bit better for the people that dont understand the original one ( like me cus im dumb).


Pin 19 - Ground -------------------Harness ground.
Pin 26 - TPS Ref voltage ----------2A
Pin 21 - Water temp ---------------2I
Pin 20 - Intake air temp ---------2L
Pin 23 - O2 sensor ----------------2D
Pin 33 - Rear primary injector ----3C
pin 35 - Rear seccondary injector- 3F
Pin 32 - Front primary injector ---3E
Pin 34 - Front Seccondary injector 3H
Pin 28 - Main Relay ---------------3I
Pin 22 - Throtle Sensor -----------2G
Pin 8 - Ground ------------------2C
Pin 9 - Ground ------------------2R
Pin 10 - Ground ------------------3A
Pin 11 - Ground ------------------3G

Vr2 In - Crank Angle Sensor (+G) --1N
Vr2 Ground - C.A.S(-G) ------------1P
Pin 7 - Crank Angle Sensor(-Ne) --1Q
Pin 24 - Crank Angle Sensor(+Ne) --1T

Pin 37 - Fuel pump check wire.

LED(-) 14 -------------------------1V
LED(-) 15 -------------------------1U
LED(-) 16 -------------------------1X

 

It all looks nearly perfect to me, except that the 2C ground is a slightly different category of ground (Vref common), and Ken has suggested that it go to pin 19. Mine is still on pin 8 and it works fine too, but I did have to add filtering for the TPS and stock MAP sensor (boost sensor) inputs. Don't know if the filtering is related to the ground selection or not.

There are spare pins that can be used for the signals that you haven't assigned to a pin - I've used 3, 4, 5, 6 for CAS G+ and the LEDs respectively, and 2 (one of the ground pins) for CAS G-.

 

wow, thank you. duely noted.

 

so where would i need to put it then if i dont wanna have a filter?

pin 19 i assume right?

 

in most cases you don't need a "filter" anyway, at least I haven't needed one so far. But pin 19 is what's "meant" to be the sensor ground... so that's the best place to run it.