I'm building an engine management system for someone, and I need to have an understanding on how Honda does Crankshaft Position Sensing.

The car is a 1994 Honda Accord with a JDM H22A4 Swap.

It appears honda uses a Denso Style ECU for these cars, and from my past experience (mostly ford/mazda, some mitsubishi) with this style of ECU they tend to use a 24 and 1 tooth dual VR triggering system mounted inside the distributor.

Other possibilities include a crankshaft mounted trigger wheel and VR sensor. If this is the case I'd need to know the number of 'teeth' on the trigger wheel, and how many wires go to the sensor (usually two and a shield, so three).

It could be a hall effect style trigger device also mounted in the disty, I have also seen optical sensing units on some mazda/toyota cars.

If there is anybody familiar with the h22a4 jdm swap, that knows how the thing works, maybe you can help me out.

The problem is, the car is in South Carolina, and I am in Florida. And surprizingly, no one here in florida wants to let me pull apart their car to find out how it works.

I'm supposed to get a call from the guy later today, so maybe I can talk him through what I need to know over the phone.

If any of you guys happen to know how this work, and help would be much appreciated.

I haven't played with too many hondas (I'm from Detroit), so forgive my lack of honda knowledge.

Knowledge on other things, electronics, tuning, stuff like that is pretty much universal and I have a bunch of it to offer to the site.


my aim screen name is the same as my handle here.

For anybody interested in what kind of engine management system this is, it is the open source megasquirt project EFI system, I've been working with them for a few years now. Google can find it :-).

 

Closest experience I've had is a '95 B18C1, but probably yours is something similar. Lets see whether you get any more specific answers, but...

Three hall-effect sensors down inside the distributor.
CYP = cylinder position
CKP = crank position
TDC = top-dead-center

I don't remember how many teeth, maybe you can see the star-wheels down there if you take out the coil & ignitor?

Each sensor had 2 signal wires, one of which is shielded. So from the distributor, 6 of those wires in the harness are from these sensors. I'm guessing wire colors aren't the same as mine.

Newer Hondas had fewer sensors, with unevenly-spaced trigger wheels to encode timing, so don't assume the same for all years. I don't know of any with optical sensors but that's only based on the cars I've owned...

 

The sensors in the distributor are magneto-resistive, not hall effect. Similar concept, but different output.

I believe the tooth count is something like this:

CYP - 4
CKP - 28
TDC - 1

 

Excellent... that is exactly the info I needed.

your magneto resistive is what I called the Variable Reluctance.


That triggering setup provides the ability for both disty and coilpack control, even coil on plug operation.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ryanpzz &raquo;</TD></TR><TR><TD CLASS="quote">your magneto resistive is what I called the Variable Reluctance..</TD></TR></TABLE>

That also. It gives a sine wave output, instead of the square wave that a hall effect would give.

 

Yup,

And you have to build a variable reluctance conditioning circuit to interpret that sine wave.

Basically triggering an event, in this case on the processor interupt line, on the negative going zero crossing of the wave. This provides a rather accurate and reliable way of identifying engine position.

Its hard to break a low current carrying coil wrapped around a permanent magnet.

 

Unless the bearing in your distributor dies and siezes up going down the highway and burns up all the sensors and leaves you on the side of the road at 2am when it's 35* outside and it takes 2 hours for the tow truck to come.

That might have happened to... someone I know. Damn honda distributors.