18DET CAS inside pics

[Seishuku]

I was just wondering if anyone had any pics of the insides of the CAS for everyone's loveable CA18DE/T. I ask because I'm interested in moving over to a different engine management system, and I'm looking to see if my current CAS is anywhere near compatible.

SHIFT_thanks!

[float_6969]

I haven't but the FSM gives you an idea of how it works.

Essentially there is a circular plate with slits in it. On one side of the plate are LED's and on the other side are optical sensors. When a slit passes over an LED a voltage spike is created. The internal circutry of the CAS takes that analog signal and creates a square wave, or a digital signal. The ECU then uses that information to know the engines RPM's, and current crank angle.

Biosehnsutch and I were trying to make a converter so that we could use it for input on the SDS but we couldn't get it to work.

[Seishuku]

Yeah, I know how it works, I was just wondering how different it was setup from others (slot pitch, how many slots, how many rows, etc).

[biosehnsucht]

It's down to a software issue and I just haven't had the time to sort it out, the hardware works its a matter of finding the right duration for the cyl 1-4 sync points in the cas signal..

there are two outputs, the 1deg signal (so should be 720 per rotation presumably since we're measuring the cam), and the 180 deg signal (which goes active only at the 180 deg marks for cyl 1,2,3,4.. cyl 1 has a longer mark than the others)

signalling should be more or less the same as other 4 cyl nissans w/ CAS or dist such as KA, SR, CA.. similar also to VG and RB but of course they have more sync points for extra cylinders..

trying to count the blips by hand while slowly turning it is useless so I just need to mock up a slightly over-engineered prototype that spits out the timing information on serial port so I can find the proper settings to use.. just haven't got around to it.

[float_6969]

Lazy ***... Oh wait, you're doing this on your free time. Nevermind! Hehehe, JK! Lemme know if you ever get around to it though, as I'd still like to test it out on the car and see how it works.

[Seishuku]

Ok, so it's slot setup is one row of 360 or 720 slits (there's a lot) and one row of 4... That's VERY interesting, because that's exactly how the older SOHC encoders are set up. Thanks for the info!

Basically what this means, is that I could run an OEM CA18DE/T management system on my CA20E with just a little modification to the connectors.

Edit:So the disc looks like the attached?

[float_6969]

yes, but it's only got 360 slits on the outside. At least that's what the FSM says...

[Seishuku]

Hmm, interesting. Though I can't really see how the number of outside slots would matter, since last I checked it's for ignition timing, so more could make more acurate (depending on how the ECU times it of course).

[biosehnsucht]

it says 360 1 degree slits which makes no sense since it has to be 720 total crank rotation, perhaps its 360 of the cam degrees. but until I get around to making a prototype variation w/ input counter and serial output I won't know for sure..

[Seishuku]

Yeah, I just gave my disc a quick rough count and it would seem to be 360, but if you combine that with the 180 degree slots with the TDC wide slot and you can get everything you need pretty much.