Megasquirt Newbie Questions - All the really dumb ones you were afraid to ask!

So what IS used on yours - where's the connection from, that gives the rpm signal to the ECU?

 

Me too....

So effectively, once you switch to a fixed dizzy from a digi car, the spark window signals TDC to the TCI unit, via the hall sender, so at that point the ECU needs to be involved to control the advance offset.

I'm assuming it must always be taking a reference point from the previous TDC signal (so working one spark behind) to offset the advance for the next one, and making assumptions based on the rpm signal.

So if I use the diagram as per vintage water cooleds, as far as I can tell, the Hall signal will hit the TCI unit, and the TCI unit will fire the coil, without involving the ECU. Does that mean it would always be at TDC with no advance?

I've been trying to get my head around how the ECU signals when to fire the coil. I assume if Pin 24 is the rpm signal to the ECU, then Pin 36 is the trigger for the coil (Hall sensor + any advance that the ECU adds.)

to be continued...

 

Does a digi dizzy have a 4 window hall? You can problay fix a kr dizzy.

 

I couldn't find the diagram you meant, but I think yes Mike. If you wire up your fixed dizzy to the TCI unit, it'll always have the same advance, depending on how you set the timing with a light.

The difference between distributor Hall sensor behaviour:



Curiouser and curiouser!

edit: I think a digifant dizzy is four window/fixed advance isn't it? Falling edge or rising edge trigger?

I'm going to go outside and test a kjet dizzy and a 2E dizzy for a comparison now.

 

This shoulD help

http://www.msextra.com/doc/ms1extra/MS_Extra_Ignition_Hardware_Manual.htm#MSnS

 

... continuing....

So I think it's starting to make sense to me. This is how I'm rationalising it at the minute...

Hall sender sends the TDC signal to ECU Pin24, ECU applies the timing advance and fires a signal from ECU pin 36 to TCI unit at pin 6 (which was the hall input), which in turn fires the coil from pin 4 of the TCI (as standard). That way the TCI unit gets the adjusted hall input via the ECU.

The earth from the Hall sender, which was to the TCI unit, now goes to the ECU. I'm not sure why it needs to. Maybe it's optional, but it's no hassle to do it.

I'm not clear on why the + on the hall needs to move from the TCI unit to the coil + (optional?)

 

Yes, the PB digifant type dizzy is 4 window, as is a 2E.

ADY and AGG are one or two window I think.

 

Engine speed input.

MS pin 24 is triggered by hall dizzy (0) or signal.
TPS 5v ref powers hall dizzy (+)
Pin 7-11 earths the hall dizzy ( there are 5 long black wires on the RSA loom for the sensors) (-)

Ignition output.

You are outputing a fixed dwell ECU signal to the TCI-h ignitor via pin 36. This is signal can be set to "inverted" if the ecu was built with and ignitor. In your case set not set as such.

This goes to pin 6 on the TCI-h from Pin 36 on the MS Pin 36 next to F/P relay Pin 37.

The & pin TCI-h is wired as;
T7/7 not used
T7/6 from MS PIN36
T7/5 not used
T7/4 KL15( ignition coil supply)
T7/3 not used
T7/2 Gnd to battery
T7/1 coil -ve

*Edited*

I would remind the those who are inputting that this ECU was tested on the car of a similar set-up prior to sending to Mike. The infomation given creates a std integration format to enable remote support.

 

Thanks Eddie.

Maybe I'm taking this slightly out of context, but I think you've contradicted your previous post here.

Compared with

So I run a jumper cable from the TPS 5v + to the Hall sender 5v Ref. Roger willco.

Looking at the stock wiring (Post 57 above), where pin 3 is the earth from the hall, I think you might mean pin 4 for the output to the coil from the TCI (above). Can you double check and confirm, please?

 

T7/1 is pin 1 on the T7 connector.
MK2 digifant red/black, Kjet Green.
In my response to yourself I did not use the VW designation or color codes and have mixed up the coil supply terminal 15 or KL15 with unused pin 3.
Now edited.

Yes make a common connection with TPS 5v ref to power the hall on (+), earth on (-) with one of the 5 long black wires from the RSA loom.

 

Can i take you at the very beginning again? ;p

I have a MS2 v3.57 with extra code and a full loom from diyautotune.Should i take all the old loom and ecu out of my mk2 16v? or should i leave something in there?

cheers

 

In case it's of any interest, I've just gone out and tested my Hall sensor.

Window facing Hall sensor, signal reads 0.1V:



Metal in front of Hall sensor, signal reads 9V:



Distributor set with rotor arm pointing at mark on housing, ie: when spark should fire on No1 cylinder:



So the transition from window to no window ie: -ive to +ive volts or 'rising edge' triggers the spark, on this distributor, part number 037 905 205 J (2E engine code). I'll pop out and test the Kjet mechanical dizzy which came with the TCI unit, shortly.

 

I think the normal approach would be to splice that into your existing loom.... You don't need the old ECU though.

 

Ta!

 

Thanks Mike.Wouldn't it be more clean and tidy to remove everything though and just connect everything to the new loom? or is it too difficult?

 

It was easier for me to splice into existing loom, as it has its place in the bay, already wrapped and is already connected to various sensors etc.

 

In my case there are bits of the original loom that I'm still using, and where I'm not using the original loom, I'm still using the original type connectors with pigtails left on to splice the RS Autosport loom into. I suppose it's a halfway house, as there are bits of the original loom that will be discarded (or left on the car until I decide it's definitely never going back to Kjet).

If you want to make a new engine loom, you'll be reworking bits that you probably don't need to replace.

 

Thanks tshirt2k and Mike for your inputs.I'm not sure what to do yet because my old loom is dirty and don't know if all the wires are ok since its there for 20 years and the engine bay was dirty like s**t and very untidy.. that is why i prefer using the new loom which on each wire is written for what it is for and also i'm not using anything stock such as coil,ignition module,distributor or k-jet.I'm going to use wasted spark coil and 1.8t rail with injectors.I'm thinking about some sensors if they will be easily sorted out with the new loom,for example oil pressure sensor because i'm not familiar with this job/ecu stuff and wirings..

 

Also how about a relay board? shall i use the stock one?

 

You don't need a relay board. Use OE supplys and relays etc.

Mike i'm sure you will never go back to kjet after getting MS up and running.