Crank Angle Sensor type question

[Ben Fenner]

mike kojima wrote:
> It's an infared LED shining through a round plate
> driven from the distributoer shaft with a whole bunch
> of slots blanked into it. 

After reading the FSM, I'm very familiar with the way it works. The 
problem is VEMS. It handles two signal types, and they discribe them as 
"VR" and "HALL". It turns out the photo-plate sensor Nissan uses 
produces the same signal, and requires the same power delivery as a HALL 
type sensor. As far as the ECU is concerned, we have a HALL crank angle 
sensor, and cam angle sensor, built into one.

The guys over at VEMS have tried to do a software seperation of these 
two signals, but scrapped the idea do to the processing overhead. They 
recommend discs with 24 cam angle holes, and 1 crank angle hole.

See this link to read more:

http://www.vems.hu/wiki/index.php?page=VehicleFitment%2FNissan




> its not a hall or VR
> sensor at all, which work by inductance to create the
> signal.

I am well aware of this. I guess I was asking what type of signal it 
would create for the ECU.


> I would not simply trust any non OEM wideband to
> activly manage anything near WOT based on the wide
> scatter of readings I experianced with my test.  I
> would at least verify the readings against a known
> reference.
> 
> I was shocked and dismayed with the results of my test
> and how differently the different meters worked.

I understand you were using stand-alone WBO2 sensor controllers. Did you 
test any ECU-based controllers? Would you trust a stand-alone ECU to 
handle controlling a WB any more than you would a dedicated WBO2 sensor 
controller?



> You NEED a crank angle signal for any stand alone ECU
> to work, I don't understand why you think its not
> needed.

I understand this, and was never fuzzy on this concept. If you go back 
and re-read what I said, it's clear I understand this already. =]



> If you wanted to you can simply use the crank angle
> signal generated by the distributor and use it to run
> a DIS system.  

See above link. This is the VEMS's user created solution for the Nissan 
trigger problem.


> Or a nicer looking althernative is to
> use a S14/S15 DET crank angle sensor in lieu of a
> distributor.

This sounds very promissing, and easier than the VEMS modified disc 
solution. Do you have any more information about this?




> I would be careful of many aftermaket DIS conversion
> ideas, most of them are waste spark systems that fire
> the plugs with every revolution and have a short dwell
> time to saturate the coil.  I have found these to be
> prone to missfire, although its been 20 years since I
> messed with the first primative electromotive systems.

VEMS does distributors, and coil-on-plug (passive or active). Either of 
these methods can be used in a wasted spark fassion. I know how to 
implement all of them, and I'll be working with my distributor for a 
while, and then move to coil-on-plug (without wasted spark). So you can 
rest easy there. =]


> I sort of worry about how much understanding you have
> to work this stuff based on some of the questions you
> are asking or perhaps it is me not understanding you
> properly.

I believe you've missunderstood me a few times. I'm not as stupid as I 
know you think I am. =]

Really, you don't have to worry about me. I don't spend money, or take 
action until I know exactly what I'm dealing with. I can only say, just 
you wait and see.

-Ben Fenner
1994 Black SE-R (going turbo)
1994 Black SE-R (with sunroof)


> 
> --- Ben Fenner <fenfam at sc.rr.com> wrote:
> 
> 
>>Yah, I realize it is the controller itself which
>>makes or breaks the O2 
>>sensor, but I'm going to put my trust in VEMS, and
>>assume, at the very 
>>least, that their digital WBO2 controller is halfway
>>decent. I don't 
>>plan on using race gas ever, so I don't have to
>>worry too much about 
>>fouling it up.
>>
>>I've been reading through the factory service
>>manual, and I found the 
>>bit about the cam angle sensor. Like you said, it's
>>optical, and has 360 
>>degrees of resolution. So, that's the cam angle
>>sensor. Awesome. But is 
>>it a VR type, or Hall type? Wikipedia says:
>>
>>So... our optical sensors are not Hall type. I
>>guess. But are they the 
>>VR type? Or something Nissan specific? I only ask
>>because MegaTune has a 
>>specific setting for Nissan type sensors... =/
>>
>>After reading quite a bit about distributor and
>>distributorless 
>>ignitions, it seems there's no need for a crank
>>angle sensor if you're 
>>running a distributor. I plan on going to passive
>>coil-on-plug ignition 
>>after initially getting things working with the
>>stock distributor. I'll 
>>have to do something about crank angle sensing at
>>that point. I may have 
>>to build my own... But I'd rather not. How does the
>>stock ECU get its 
>>tach signal if its not using a crank angle sensor?
>>From the ignition, 
>>which is subsequently controlled by the cam angle
>>sensor?
>>
>>I'll keep looking for these answers, but if any of
>>you know the answers, 
>>just chime in. Also, do we know of anyone in the
>>Nissan community who's 
>>really familiar with these sort of things, or am I
>>blazing the trail? I 
>>guess Calum would know this stuff. Maybe it's time I
>>hit the forums... =/
> 
> 
> 
> 
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