Wiring loom build and i/o questions

[Twinspark]

Hello all,

I have completed and tested MS3xV3.0 with knock sensor and RTC and am now designing the loom.

The motor is a 1990 Alfa Romeo 2.0 8V Twinspark which currently uses Motronic 4.1 (flap type air flow meter, 60-2 crank wheel VR).

VR 60-2 via 24 on main board
Hall cam sensor via 32 on MSX board
Ignition - Sequential Coil on Plug from MSX board via a pair of Bosch 211 drivers
Injection - sequential from MSX board
Wide band O2 (analog via MSX Board)
Knock sensors (SP3 and SP4 main Board)

Additional functions I would like provision for are:

VVT intake cam only (on/off type)
idle valve (PWM 2 wire)
Evap purge solenoid (on/off)
Wheel/vehicle speed (pulsed speedo signal from gearbox)
Tachometer output to drive factory tacho
MAF (analog)
Boost control (maybe one day....)

My question is what are the best channels to use for these functions? It seems that there are many options and some traps. Thanks!

[Twinspark]

Heres what I was thinking....

VVT intake cam only (on/off type) VVT 27 or Nitrous1 24 on MSX board
idle valve (PWM 2 wire) Idle 9 MSX board
Evap purge solenoid (on/off) Nitrous2 25 MSX board
Wheel/vehicle speed (pulsed speedo signal from gearbox) PT4 MSX board
Tachometer output to drive factory tachometer Tacho 26 MSX board
MAF (analog) Spare ADC 21 MSX board
Boost control (maybe one day....) Boost 6 MSX board


On/off VVT is RPM/load dependent and impacts ignition timing a bit, I'm interested in ideas on how to manage timing with VVT.

[CRSTune]

On/off VVT is RPM/load dependent and impacts ignition timing a bit, I'm interested in ideas on how to manage timing with VVT.

You could keep it simple by simply tuning a single spark table (you said MAF so you won't necessarily need to tune a VE table unless you want to). Set your VVT On/Off table and tune ignition timing accordingly.

If you want to make it more complicated, you can also activate table switching to follow VVT On/Off in the Table Switch settings. You'll have two separate tables for both fuel and spark.

[Twinspark]

Thanks CRSTune,

I'll probably tune MAP to start with, and do MAF tuning at a later date. Table switching sounds like the way to go as VVT on/off changes VE, I'll read up on that.

So to use Table Switching I need to use VVT 27?

I have a factory loom that ive opened up and will use sections of it in the MS loom, power supply side and chassis loom interface for instance. I'll use new sensor and injector/coil connectors as many of these are broken or in poor condition.

[CRSTune]

Thanks CRSTune,

I'll probably tune MAP to start with, and do MAF tuning at a later date. Table switching sounds like the way to go as VVT on/off changes VE, I'll read up on that.

So to use Table Switching I need to use VVT 27?

I have a factory loom that ive opened up and will use sections of it in the MS loom, power supply side and chassis loom interface for instance. I'll use new sensor and injector/coil connectors as many of these are broken or in poor condition.

Yes, you can use pin 27 (and probably should just to avoid confusion). It's labeled as "VVT" but it's probably just easier to remember it as one of 6 medium current, PWM outputs.

As far as table switching goes, you'll program the "Switch Source" as "On/Off VVT." In this case, it refers to VVT as a software function, not the actual output. The actual output will be whatever you program into the VVT settings.

Yes, VE does change whether VVT is engaged or not. Keep in mind though that unless you intentionally program the software to not allow VVT to engage under certain conditions (warm up for example), it will always be operating at the load sections you tuned with it. That would mean there shouldn't be any deviations in the overall efficiency at any load point. That would imply that table switching for On/Off style VVT is likely unnecessary for most users.