SC Ignition Distibutor Green wire - modify for sequential?

[NaFe]

Hey guys,

 

I was wondeirng whether people could explian what the function of the green wire from my distribuor is? I presume its a tach signal to the CDI Box.

 

The reason I ask, other than I dont know , is that I am in the process of upgrading to fully sequential efi setup.

 

I'm replacing all of the K-Jet with 3.2 intake setup and an MS3/MS3X Megasquirt ecu.  I'm opting for sequential rather than wasted spark and was wondering how you could modify the distributor to use as a sensor for cylinder1 location.  The norm seems to be fitting a sensor into the end of the camshaft but I'm a bit weary about doing this.

 

I'll be running:

3.2 manifold and throttle body with IAC valve,

3.2 fuel rail with replacement injectors (high impedence)

Coil on Plugs with built in drivers

then the additional sensors like MAP, throttle, o2, crank and some kind of cam/dizzy

 

I'm currently building up my ECU from a kit and have got as far as the basic build where i have loaded the firmware and i'm ready to start parameterising it - dependant on which sensor types i'm going for

 

Your help/advice would be much appreciated.

 

NaFe

 

[Russ]

I think from reading my MSD install stuff yesterday (and 101 projects) tacho wire is black with a purple trace on it.

 

I'm pretty sure green wire goes to magnetic pickup or points

 

more info here - http://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/24-MSD_Install/24-MSD_Install.htm

[NaFe]

Thanks for the quick reply.

 

I agree that the Black and Violet wire "carries" the signal from the Elctronic Ignition unit to the actual tach on the dash, but does the signal come from the magnetic pickup from the distibutor or from the coil?

 

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part1-2.jpg

 

either way, the fact that the green wire is a magnetic pickup, then it must be able to be used/modifed for position of cylinder no.1???

[Russ]

according to what I've read (and I'm no expert, just learning this for the first time to fit my MSD) the tacho gets it's signal from the CDI, and it's just storing capacitance on behalf of the coil in high revs - so I assume the signal from the distributor which is where the timing will come from (so it must know what is where timing wise)

 

are you running a crank angle sensor? I guess it would do what you need to do? have you talked to uncle?

might be worth looking at a 964 setup (where they have a notch in a flex plate on the back of the engine to sense TDC)

 

also, are you reinventing the wheel (don't mean to sound rude) but have you checked on pelican for what the options are? maybe there is a distributor already available to do just this?

[NaFe]

I will be running a CAS yes, but in addition to a cam/dizzy sensor.  On its own it will not do what I want it to do unfortunately.  The crank rotates 720degrees for every 360 degrees of cam/distributor! if I were going down the use wasted spark route then yes i would simply be using a CAS and I would not need to worry, but as I am running sequential it needs to know where TDC of No.1 is - i.e. cam or dizzy ssensor.

 

I have looked on PP yes and I have not really come across any build threads of people modifying their distributor for sequential timing.  most people go down the cam sensor route which involves permanently removing a dust cap, drilling and tapping in the end of the cam, fitting a bolt followed by the clewett cam sensor.  If you have a 930 then you can fit a modified oil pump with built in cam sensor too.

 

this is the clewett kit:

http://forums.pelicanparts.com/porsche-911-technical-forum/678799-cam-sync-sequential-efi.html

 

Lets see if anyone has done it or can explian the ins and outs of the green wire and what type of sensor it is connected to on the distributor.

[Zelrik911]

I am sure I have seen somewhere a picture with a simple distributor replacement unit. No cap or HT wires, just one lead (optical pickup maybe??) going off to the ECU brain. Perhaps you wouldnt need to use a 911 dizzy - any old Bosch unit that fits in the hole could be modified to make a simple signal switch. I will keep looking.

  

BTW I wouldnt play around with that green wire as they are really expensive. (Five inches long and cost about $100 ex usa!!!! ) Fabricate your own connectors  if you go down that path.

 

Here is some info on the green wire from Renlist:

 

The green cable on single distributor cars sends the signal to the spark TSZ unit, tach and brain. 

It is a shielded coax cable with a Bosch two pin connector on one end - the wire has a core that handles one side of the polarity for the signal, and then a braided casing that handles the other. So you have both positive and ground in one casing

 

What makes it unique, and pricey, is the pin configuration on the distributor end.

 

The crank timing sensor replaced it for L H cars.

 

I will also send you a PM

Peter - Kew

[Zelrik911]

Good relevant thread on Pelican

 

http://forums.pelicanparts.com/porsche-911-technical-forum/724690-megasquirt-iii-use-flywheel-crank-position-2.html

 

Its all good but see responses 18 & 30

 

Here is a pic of a modified distributor in a 911 3.2 (I think):

 

http://forums.pelicanparts.com/uploads21/P10100911358032843.jpg

 

 

[NaFe]

I notice that someone on there had used some internal components from a later dizzy in their older distributor for hall sensor pickup.

 

thanks Zeldrik, I'll pm you back now

[Russ]

i'm watching with interest as i'm going to do this on my next engine

 

Alison/crane makes an optical conversion for a distributor but i'm not sure if it'll give you what you want