Honda crank sensor spark control and MSII incorporation

[shize]

the subject says it all...except:
This is for a 91 civic dx with dual point injection swapping in a d15b vtec using the MSII pcb3.0.
Im hoping to use most of the original harness as the motors are very similar. I would like to reliably control spark without the use of the factory ecu or having to use the coil negative as the trigger because i am kinda under the impression that this is unreliable. I've read somewhere that there is a engine position sensor built into (or around) the distributor.
Is there a sensor there and if so how do i use it to control spark and timing advance.
On a side note could i use MS to control retard if i set the distributor back a bit than advanced it with MS past the 0 degrees point or is that beyond the mechanical limits of the dist...

[Abaddon]

I too am trying to megasqurit a similar car (a 1990 honda crx) and I am stuck on the ignition. I would like to control the ignition and fuel without the use of the factory ecu and use megasquirt II pcb v3.0.

From what I can determine, the distributor has 3 sensors in it along with the ignition coil and ignitor unit. According to the manual there is a cylinder position sensor, a TDC sensor and a crank angle sensor.

Looking in the distributor, I can see a small wheel with 4 teeth on it and further down the shaft, another wheel with 16 teeth on it.

The engine is a d15b2 SOHC 1.5L 4 cylinder w/ 4 injectors.

My questions are:
How do I determine the type of sensors these are (VR, Hall, etc)? Which sensors will be used by megasqurit? Will some of these sensors just remain unused with meagsquirt?

Thanks in advance.

[FoundSoul]

Looking these up in AllData here's what I found:

Both the 91 Civic DX (assuming HB) with d15b1 engine and the 90 CRX with the d15b2 engine have the exact same distributor.

There is a 4 toothed wheel right up front, should be pretty easy to see when you open the dizzy. That should trigger the MS just fine and as this is a toothed wheel this is a VR sensor reading it.

You could use the MS-I with MSnS-E firmware or the MS-II, either way I'd definitely stick with the v3 PCB for several reasons, not the least of which is the built in VR conditioner which you'll need to read this sensor.



According to AllData-- the wires for the 4 tooth wheel's sensor are WHT/BLU and ORN/BLU from the distributor to the ECU. I can't tell for 100% sure which is + and -. I'd guess the WHT/BLU is + but that's purely a guess based loosely on this drawing.

The 16 tooth wheel is WHT and ORN color wires, just FYI.


Hope this info helps you guys out!

[Abaddon]

Thank you for looking that up. Here's what I have gathered on the wire colors from my manual:

Orange/Blue - TDC Sensor
White/Blue - TDC Sensor

Orange - Crank Sensor
White - Crank Sensor

Blue/Green - Cylinder Position Sensor
Blue/Yellow - Cylinder Position Sensor


So, with your info we've got:

Orange/Blue - TDC Sensor (4 tooth wheel VR sensor -/ground)
White/Blue - TDC Sensor (4 tooth wheel VR sensor +)

Orange - Crank Sensor (16 tooth wheel VR sensor)
White - Crank Sensor (16 tooth wheel VR sensor)

Blue/Green - Cylinder Position Sensor
Blue/Yellow - Cylinder Position Sensor


It also just occurs to me that I was looking at the DOHC distributor for my ZC motor when I posted. On that motor the Cylinder Position Sensor is separate from the distributor and resides on the exhaust cam. I'll take a look at a SOHC distributor later this evening and see if I can't find out about the Cylinder Position Sensor. (Wheel tooth count, type, etc.)

I am currently in the process of building up my MS II PCB 3.0 right now. It sounds like I will use the TDC (4 tooth wheel) VR sensor to trigger MS and I will build the MS with the high current ignition driver circuit to control the coil. Sound right? Does this mean the other two sensors won't be used for anything? If so, why does the OEM ecu use all these sensors and MS doesn't? Will I use the ignitor too, or just the coil?

Would MS be able to control the timing more accurately with one of the other sensors, seeing as they have more teeth? Or would that just result in the signal becoming blurred at higher rpms and actually make my timing less accurate? I'm looking for the best solution using my stock distributor. Thanks.

[FoundSoul]

For a 4 cylinder car you need a wheel spinning at cam speed with 4 evenly spaced teeth, nothing more. OEM's do all kinds of crazy stuff that I can't explain and make systems way more complex than they need to be sometimes, maybe they have reasons (like sequential injection or COP in some cases, don't think that applies to you here), maybe not, but the MS just needs that 4 toothed wheel. Any more than this and the MS will mis-read your RPMs... that is unless you setup a missing tooth wheel and do wheel decoding, but you have no reason to go there.

Here's an article I'm working on that so far covers this topic pretty well, I've got more work to do:
http://www.DIYAutoTune.com/tech_article ... ontrol.htm

You can either NOT use the IGBT circuit and try using the stock ignitor, or ditch the stock ignitor and use the IGBT circuit (which is an ignitor) to fire the coil... your call. Either can work really well...

[Abaddon]

Thank you for the article, it clears things right up. The info you provide should be on the megasquirt site's ignition control section. Invaluable!

[FoundSoul]

I'm really glad to hear it was helpful for you-- I do have alot more work to do on it as I want to cover the myriad of other ignition options that are available, and I've really only got the most basic distributor setups covered now, though I was getting asked about those setups quite often and wanted to help people to be able to determine compatiblity of their own ignition system with the MS, as half the fun of this project is learning the in's and out's in the process ;)

I'll have to get back to work on it soon... so much to do, so little time ;)