Hi guys

Can someone check the ohms on the crank position sensor of 83' turbo dizzy. I have big problems with my megasquirt re-install and would like to find out if my CAS sensor is bad.

Green wire to Black(ground) I get 103 ohm. White to ground I get open circuit. green to red(power) is 106 ohm. white to red is 6.8 ohm

I'm no electronic guy by any means I barely know what an ohm is. Please don't get to technical on me.

Another question s how does one change the sensor? Do I use a puller to get the center round dics off(see pic) then I assume the circuit board and sensor can be removed!

 

regards

Dave

You sure you installed the encoder wheel correctly? Also I thought  for MS the suggestion was to use the Z31 encoder wheel flipped with the Z31 crank angle sensor. I could be mixing this up with using the 300zx ignition system on the L6.

i used a pair of vise grips and lightly locked on and slowly rock back and forth. 

Edited December 15, 20177 yr by JSM

I'm sure @Chicken man will chime in. 

The CAS doesn't have a resistance that you can check, like the pickup coil does in an EFI 280ZX.  It's transistorized.  Power supply to the CAS is important.  Many ways to have problems with Megasquirt.  Some people can't get a known-good CAS to work well with Megasquirt.  It takes some tricks.

If you insist/persist though, like JSM says, that piece just gets stuck and can be rocked or pried off.  No need for a puller.  But, better to describe your "big problems".  I would stop disassembling your CAS now, especially if you barely know what an ohm is.  Really seems like you might be on the wrong path.

Edited December 15, 20177 yr by Zed Head

It was not mentioned, so I will add,  there are 2 or 3 screws on the underside of the distributor that hold the CAS in.   

9 hours ago, S30Driver said:

It was not mentioned, so I will add,  there are 2 or 3 screws on the underside of the distributor that hold the CAS in.   

Isn't there two screws for the plug too that need to come off first.

3 screws hold CAS in place but the round disc needs to come off first. It's really on there. Marked the trigger wheel side up a long time ago. Been there done that.

I had this engine running for a couple years exactly the way it is now BUT, a couple years ago when I went with Megasquirt MS3X I made my own MS, MSX wire harness. The engine ran ok but I did have an annoying IAC valve issue and other issue was when I ran boost above 9-10 lbs I have what I think is injectors shutting down- -so I purchased DIYAUTOTUNE harnesses. While installing I messed up and crossed the cam, crank and ground wires at the distributor. I suspect I cooked the CAS.

That what's driving this post:).

Last night I used 12v power supply to the red and black CAS connector. Green wire I would get 1.3v at on point on a revolution. White wire I get no voltage. A guy at Hybridz suggested I do this. He did say one of these 2 wire needs a resistor in line. I hope he responds today.

Will try the junkyard tomorrow. Rock Auto has the CAS for $120 delivered. I'd like to confirm mine is bad before purchasing a new one. Concerned MS is damaged as well.

 

If you do end up with a replacement CAS, you may find that the 3 brass holes for the screws are not threaded.   I had to use longer screws & nylock nuts to replace them.

You can also get the CAS from NAPA.

I spent some time dinking around with junkyard CAS's and the internet when I was thinking about modifying a later Nissan distributor/CAS for my L6.  The basic photodiode technology hasn't changed since their introduction.  I think that pinout might even be the same.  You might find that you can swap in a later model CAS module in with minor modifications.  Plastic tabs and hole changes.  Look at the 90's Pathfinders, there's a ton of them dying these days, the yards always have them.

I learned how to get that metal disc/cup off, the one you're working on, in the wrecking yard.  Some of them were just plain stuck and would probably never come off.  Locked on by corrosion.  Some popped right off by hand.  It's a very precise fit on the shaft.

Here's something else to consider.  The MS system generally doesn't work that well with the Nissan wheel, for whatever reason.  DIYAutotune made a fairly cheap wheel for the application.

https://www.diyautotune.com/product/54-mm-optical-trigger-wheel-for-nissan-l28et-or-vg30e/

Here's an example of what a person can do if they value money more than time (nothing wrong with that, or vice versa.  Personal choice) or just want to mess around.

http://forums.hybridz.org/topic/62575-z32-and-rb-cas-disassembly/

I have the same thread running over at hybridz.

Chickenman gave great advice to use a later model CAS. SleeperZ nice advice on checking function.

 

off to the junkyard tomorrow.

I just pulled one myself recently. Take a sharpie, mark the top of enoder wheel and take apart there. It was way cheaper then buying the whole distributor.